Journal articles: 'Group Velocity Dispersion (GVD)'

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LIU, YE, BO FANG, LILI WANG, and CHUN JIANG. "SLOW LIGHT AND DISPERSION COMPENSATION BY CASCADING TWO PHOTONIC CRYSTAL WAVEGUIDES." International Journal of Modern Physics B 28, no. 03 (2014): 1450025. http://dx.doi.org/10.1142/s0217979214500258.

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In this paper, we propose a structure with cascaded two photonic crystal line-defect waveguides to reduce group velocity dispersion (GVD) of slow light. The width of the line-defect waveguides is tuned to obtain the two matched dispersion relations, where one of the dispersion relations has a maximum point with zero group velocity and large positive GVD; the other has a minimum point with zero group velocity and large negative GVD. The waveguides have ultra slow light with the group velocity 0.0012c. Finite-difference time-domain simulation demonstrates that the spreading of the slow light pulse in the first waveguide can be recovered by the dispersion compensation of the second waveguide with positive GVD.

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Radha, Ramaswamy, and Vaduganathan Ramesh Kumar. "Interplay Between Dispersion and Nonlinearity in Femtosecond Soliton Management." Zeitschrift für Naturforschung A 65, no. 6-7 (2010): 549–54. http://dx.doi.org/10.1515/zna-2010-6-710.

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In this paper, we investigate the inhomogeneous higher-order nonlinear Schr¨odinger (NLS) equation governing the femtosecond optical pulse propagation in inhomogeneous fibers using gauge transformation and generate bright soliton solutions from the associated linear eigenvalue problem. We observe that the amplitude of the bright solitons depends on the group velocity dispersion (GVD) and the self-phase modulation (SPM) while its velocity is dictated by the third-order dispersion (TOD) and GVD. We have shown how the interplay between GVD, SPM, and TOD can be profitably exploited to change soliton width, amplitude (intensity), shape, phase, velocity, and energy for an effective femtosecond soliton management. The highlight of our paper is the identification of ‘optical similaritons’ arising by virtue of higher-order effects in the femtosecond regime.

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Phukan, Devika, Priyanka Talukdar, and Pranami Sarma. "Designing an Air Core Photonic Bandgap Fiber to Study the Dispersion and Loss Characteristics for Optical Pulse Propagation." Journal of Scientific Research 67, no. 03 (2023): 37–45. http://dx.doi.org/10.37398/jsr.2023.670306.

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The wavelength dependence of the Group velocity dispersion (GVD) in an air core Photonic Bandgap fiber (PBGF) with 9 air hole rings has been investigated. The waveguide GVD of the designed fiber is studied and found that the GVD strongly depends on the structure and geometrical parameters of the fiber. It is strongly affected by photonic bandgap edges at the bandwidth boundaries due to the confinement of light by the photonic band gap effect. It is seen that the GVD value shifts from negative at shorter wavelengths to positive values at longer wavelengths and the zero-dispersion wavelength could be changed by changing the hole diameter to pitch ratio.

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Andrianov, A. V., N. A. Kalinin, and E. A. Anashkina. "Group velocity dispersion of a multicore fibre with 5 × 5 coupled cores for in-phase and out-of-phase supermodes." Laser Physics Letters 18, no. 12 (2021): 125104. http://dx.doi.org/10.1088/1612-202x/ac3516.

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Abstract In-phase and out-of-phase supermodes were selectively excited (with modal content >90%) in the wavelength range near 1030 nm in a silica multicore fibre with 5 × 5 coupled cores using a spatial light modulator. Group velocity dispersion (GVD) parameters of 21 ps2 km−1 and 14 ps2 km−1 at 1030 nm were measured for in-phase and out-of-phase supermodes, respectively, using an interferometric scheme. The numerically simulated GVD values agree with the experimental results. The calculated zero-dispersion wavelengths (ZDWs) of 1360 nm and 1180 nm for in-phase and out-of-phase supermodes are red-shifted and blue-shifted, respectively, compared to the ZDW of silica glass. The anomalous dispersion for the out-of-phase supermode is predicted in the telecommunication O-band near 1300 nm. The theoretical explanation of the difference in the wavelength-dependence of GVD for in-phase and out-of-phase supermodes is given.

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Jain, V., S. Pawar, S. Kumbhaj, and P. K. Sen. "Spectral and Dispersion Properties of Long Period Fiber Grating for Optical Communication Systems." Advanced Electromagnetics 7, no. 4 (2018): 109–16. http://dx.doi.org/10.7716/aem.v7i4.797.

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Present work deals with the analytical study of spectral and dispersion properties of long period fiber grating (LPFG) under linear regime. The standard parameters in the understanding of the optical features of an LPFG have been analyzed using the linear coupling processes such that one can appreciate without going through the cumbersome mathematical treatment of coupled mode equations the basic characteristics of the grating. We have analyze transmittance, phase factor, group delay and group velocity dispersion (GVD) of the LPFG as functions of physical parameters like operating wavelength, grating length, induced index change, and detuning parameter. Special attention is paid to the study of GVD with second and third order dispersion contribution as well as the filter characteristics and delay response of the grating. In case of strong grating, we find that at a particular grating strength the resonance band splits into two bands. Negative group delay for certain values of coupling strength suggested that an LPFG can also be used as dispersion compensator in optical fiber communication.

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Jiang, Kai Wei, Yu Tian Pan, Guan Jun Wang, and Jing Xiao. "Dispersion Management and Nonlinearity Enhancement in a Hybrid Nanofiber with a High Index, Cross-Slot-Structure Nanocore." Applied Mechanics and Materials 668-669 (October 2014): 17–21. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.17.

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A highly nonlinear, dispersion flattened hybrid nanofiber with a silicon/silica cross-slot-structure nanocore is proposed and analyzed, which is insensitive to polarization for implementing quasi-TE and quasi-TM fundamental modes transmission due to the cross slot effect. Simulation results show that fundamental mode with ultra-small mode effective areas and high nonlinearity at TE and TM polarizations, which are confined in the narrow cross slot by four silicon ribs, can be achieved via this cross-slot-structure core. Moreover, the cladding of four large-air-holes contributes to the tailoring of the group velocity dispersion (GVD) and further enhancment of the nonlinearity. Our results indicate that ultra-small Aeff of 0.098μm2 and flat anomalous GVD with less than 13.5 ps.km-1.nm-1 dispersion ripple at C-band are realizable.

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Wang, Guan Jun, Zhi Bin Wang, You Hua Chen, et al. "Polarization-Insensitive Holey Fiber with Ultra-Small Mode Areas Using a Cross-Slot-Structure Core." Key Engineering Materials 609-610 (April 2014): 775–78. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.775.

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A high nonlinear, dispersion flattened hybrid nanofiber with a silicon/silica cross-slot-structure nanocore is firstly proposed and analyzed, which is insensitive to polarization for implementing quasi-TE and quasi-TM fundamental modes transmission due to cross slot effect. Simulation results show that fundamental mode of ultra-small mode effective areas and high nonlinearity at TE and TM polarizations, which are confined in the narrow cross slot by four silicon ribs, can be achieved via this cross sot structure core. Moreover, the cladding of four large-air-holes promotes tailoring the group velocity dispersion (GVD) and enhancing nonlinearity furthermore. Our results indicate that ultra-small Aeff of 0.098μm2 and flat anomalous GVD with less than 13.5 ps.km-1.nm-1 dispersion ripple at C-band are realizable.

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Qian, Xinlei, Xiaochao Wang, Xinghua Lu, Tianyu Zhang, and Wei Fan. "Suppression of Frequency Modulation to Amplitude Modulation Conversion with Modified Group Velocity Dispersion Compensation Device in the Front End of High-Power Lasers." Applied Sciences 12, no. 2 (2022): 884. http://dx.doi.org/10.3390/app12020884.

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The group velocity dispersion (GVD) occurring in the front end of high-power lasers is one of the primary factors leading to the conversion of frequency modulation (FM) to amplitude modulation (AM). In this paper, we propose a modified, active, closed-loop feedback compensation device for GVD-induced FM–AM conversion, using a two-dimensional, electric, adjustable mirror mount and parallel grating pair to improve the long-term stability, efficiency of adjustment, and accuracy of compensation. Experimental results of a 12 h FM–AM depth test revealed that the depth varied between 2.28% and 5.22%. Moreover, we formulated a mathematical relationship between the dispersion parameters and temperature in optical fibers to analyze the intrinsic effect of temperature on FM–AM. The related simulation and experimental results consistently validated the quantitative relationship between the temperature and FM–AM depth.

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CHENG, CHUNFU, YOUQING WANG, YIWEN OU, and QINGHUA LV. "TRANSFORM-LIMITED SPECTRAL COMPRESSION BY USING NEGATIVELY CHIRPED PARABOLIC PULSE IN ALL-NORMAL DISPERSION PHOTONIC CRYSTAL FIBERS." Journal of Nonlinear Optical Physics & Materials 21, no. 03 (2012): 1250040. http://dx.doi.org/10.1142/s0218863512500403.

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A theoretical investigation on the parabolic pulse nonlinear propagation and spectral compression in all-normal dispersion photonic crystal fibers (PCFs) is presented. It is found that use of larger chirp can obtain higher quality transform-limited spectrally compressed parabolic pulses due to almost purely the effects of self-phase modulation (SPM) — because of its all-normal dispersion with smaller group velocity dispersion (GVD). Also, use of long initial negatively chirped parabolic pulses can lead to the most efficient transform-limited spectral compression under the optimal compression condition.

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Lavocat-Dubuis, X., F. Vidal, J. P. Matte, C. Popovici, T. Ozaki, and J. C. Kieffer. "Effects of chirp and pulse shape on high harmonic generation and absorption in overdense plasmas." Laser and Particle Beams 29, no. 1 (2011): 95–104. http://dx.doi.org/10.1017/s0263034610000807.

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AbstractUsing particle-in-cell simulations, we investigated the effect of group velocity dispersion (GVD) and third order dispersion (TOD) in the laser pulse on high-order harmonic generation and laser absorption in overdense plasmas. A 1020 W/cm−2, 35-fs transform-limited Gaussian pulse was stretched to 160 fs through chirping. When including GVD alone, the temporal pulse shape remains symmetric and no difference was seen in the harmonic spectra for opposite signs of GVD. However, when adding TOD to GVD, the pulse is no longer symmetric and noticeable differences in harmonics intensity were observed for opposite signs of TOD. We show that the higher harmonic intensity obtained with positive TOD is connected with a steeper front edge of the pulse and the appearance of strong modulations in the harmonic spectrum. The chirp broadens and shifts the harmonics. Laser energy absorption is also mostly affected by the pulse shape. Simple estimates indicate that, in the main example considered in this paper, about half the laser energy absorption (10%) is due to vacuum heating.

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Li, Dawei, Tao Wang, Xiaolei Yin, et al. "Design of Third-Order Dispersion Compensation for the SG PW Laser System Using a Birefringent Crystal." Applied Sciences 12, no. 8 (2022): 4078. http://dx.doi.org/10.3390/app12084078.

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This study aims to update the existing SG PW laser system and improve the temporal contrast and shape fidelity of a compressed pulse with a 150 fs level for multi-PW (5–10 PW). The design of third-order dispersion (TOD) compensation via a birefringent crystal was studied through numerical simulations and experiments. The dispersions introduced by the birefringent crystal were calculated using the Jones matrix element by changing the in-plane rotation angle ϕ, thickness d, incident angle θ, and temperature T, while also considering the transmission spectral bandwidth. The group-velocity dispersion (GVD), TOD, and fourth-order dispersion (FOD) of the existing SG PW laser system and its influence on the compressed pulse with different pulse durations were analyzed. The results suggest that a TOD of 1.3×106 fs3 needs to compensate for the multi-PW design. The compensation scheme is designed using a quartz crystal of d = 6.5 mm, θ = 90°, ϕ = 17°, and T = 21 °C, corresponding to the thickness, inclination angle, in-plane rotation angle, and temperature, respectively. Furthermore, we show a principle-proof experiment offline and measure the GVD and TOD by the Wizzler, which is based on theoretical simulations. These results can be applied to independently and continuously control the TOD of short-pulse laser systems.

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Sharma, Sneha, and Jitendra Kumar. "Numerical analysis of optical logic gate based on nonlinear optical loop mirror with a photonic crystal fiber." Journal of Nonlinear Optical Physics & Materials 24, no. 02 (2015): 1550019. http://dx.doi.org/10.1142/s0218863515500198.

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Ultrafast all-optical XOR and XNOR logic gates have been analyzed based on photonic crystal fiber (PCF) nonlinear optical loop mirror (NOLM). The performance of the logic operation is evaluated numerically using the coupled nonlinear Schrödinger equation and split step Fourier method. The wavelength allocation, peak power and the pulse width of signal with respect to the group velocity dispersion (GVD) and the nonlinearity of PCF affect the performance of logic gate. A highly nonlinear PCF with flattened dispersion is proposed to obtain 1 Tb/s operation.

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Wang, Lei, Lu Lu Zhang, and Feng-Hua Qi. "Controllable Nonautonomous Rogue Waves in the Modified Nonlinear Schrödinger Equation with Distributed Coefficients in Inhomogeneous Fibers." Zeitschrift für Naturforschung A 70, no. 4 (2015): 251–61. http://dx.doi.org/10.1515/zna-2014-0351.

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AbstractUnder investigation in this paper is an inhomogeneous modified nonlinear Schrödinger (MNLS) equation describing the ultrashort pulse dynamics with the distributed dispersion, self-phase modulation, self-steepening, and linear gain/loss. Nonautonomous rogue waves for the inhomogeneous MNLS equation are constructed via the modified Darboux transformation with the inhomogeneous parameters. The dynamical behaviours and main characteristics of the nonautonomous rogue waves in inhomogeneous fibers are discussed by analysing certain physical quantities. The inhomogeneous effects on the evolution of rogue waves are considered by virtue of the presented rational solutions with distributed coefficients. It is found that the group velocity dispersion (GVD) and linear gain/loss coefficients have effects on the trajectories and amplitudes of the rogue waves, respectively. Additionally, an intriguing composite rogue wave of the inhomogeneous MNLS equation is revealed, owing to the proper choice of the GVD coefficient. Our results could be useful for controlling the rogue waves in the dispersion-managed fiber system.

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Marisova, Maria P., Alexey V. Andrianov, Gerd Leuchs, and Elena A. Anashkina. "Dispersion Tailoring and Four-Wave Mixing in Silica Microspheres with Germanosilicate Coating." Photonics 8, no. 11 (2021): 473. http://dx.doi.org/10.3390/photonics8110473.

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Optical whispering gallery mode microresonators with controllable parameters in the telecommunication range are demanded for diverse applications. Controlling group velocity dispersion (GVD) in microresonators is an important problem, as near-zero GVD in a broad wavelength range could contribute to the development of new microresonator-based light sources. We demonstrated theoretically near-zero dispersion tailoring in the SCL-band in combination with free-spectral range (FSR) optimization for FSR = 200 GHz and 300 GHz in silica glass microspheres with micron-scale germanosilicate coating. As an illustration of a possible application of such a GVD, we also performed a theoretical study of degenerate four-wave mixing (FWM) processes in the proposed microresonators for pumping in the SCL-band. We found that in some cases the generation of two or even three pairs of waves–satellites in a FWM process is possible in principle due to the specific GVD features. We also determined optimal microresonator configurations for achieving gradual change in the satellite frequency shift for the pump wavelengths in the SCL-, S-, CL-, C-, and L-bands. The maximum obtained FWM satellite tunability span was ~78 THz for a pump wavelength change of ~30 nm, which greatly exceeds the results for a regular silica microsphere without coating.

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Pogorelsky, Igor V., Mikhail N. Polyanskiy, Marcus Babzien, and Mark A. Palmer. "Post-Compression of 9.2-µm Terawatt Laser Pulses to Femtoseconds." EPJ Web of Conferences 255 (2021): 11007. http://dx.doi.org/10.1051/epjconf/202125511007.

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Contemporary CO2 laser systems are capable to delivering picosecond pulses of the multi-terawatt peak power. Further pulse compression to a few cycles is possible using a post-compression in bulk materials with negative group velocity dispersion (GVD). We have experimentally demonstrated the post-compression of a long-wave infrared (9.2 μm) 150-GW peak power pulse from 1.85 ps to less than 500 fs using a combination of two optical materials with significantly different ratios of the nonlinear refractive index to the GVD coefficient. Such combination allows for optimization of the compression mechanism and promises a viable path to scaling peak powers to multi-terawatt levels.

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Deng, Zhixiang, and Meng Zhang. "Dynamics of Dispersive Wave Generation in Gas-Filled Photonic Crystal Fiber with the Normal Dispersion." Advances in Condensed Matter Physics 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/1268230.

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The absence of Raman and unique pressure-tunable dispersion is the characteristic feature of gas-filled photonic crystal fiber (PCF), and its zero dispersion points can be extended to the near-infrared by increasing gas pressure. The generation of dispersive wave (DW) in the normal group velocity dispersion (GVD) region of PCF is investigated. It is demonstrated that considering the self-steepening (SS) and introducing the chirp of the initial input pulse are two suitable means to control the DW generation. The SS enhances the relative average intensity of blue-shift DW while weakening that of red-shift DW. The required propagation distance of DW emission is markedly varied by introducing the frequency chirp. Manipulating DW generation in gas-filled PCF by the combined effects of either SS or chirp and three-order dispersion (TOD) provides a method for a concentrated transfer of energy into the targeted wavelengths.

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YANG, QIN, and JIE-FANG ZHANG. "OPTICAL QUASI-SOLITON SOLUTIONS FOR THE CUBIC-QUINTIC NONLINEAR SCHRÖDINGER EQUATION WITH VARIABLE COEFFICIENTS." International Journal of Modern Physics B 19, no. 31 (2005): 4629–36. http://dx.doi.org/10.1142/s0217979205033005.

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Optical quasi-soliton solutions for the cubic-quintic nonlinear Schrödinger equation (CQNLSE) with variable coefficients are considered. Based on the extended tanh-function method, we not only successfully obtained bright and dark quasi-soliton solutions, but also obtained the kink quasi-soliton solutions under certain parametric conditions. We conclude that the quasi-solitons induced by the combined effects of the group velocity dispersion (GVD) distribution, the nonlinearity distribution, higher-order nonlinearity distribution, and the amplification or absorption coefficient are quite different from those of the solitons induced only by the combined effects of the GVD, the nonlinearity distribution, and the amplification or absorption coefficient without considering the higher-order nonlinearity distribution (i.e. α(z)=0). Furthermore, we choose appropriate optical fiber parameters D(z) and R(z) to control the velocity of quasi-soliton and time shift, and discuss the evolution behavior of the special quasi-soliton.

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Seitner, Lukas, Johannes Popp, Michael Riesch, Michael Haider, and Christian Jirauschek. "Group velocity dispersion in terahertz frequency combs within a generalized Maxwell-Bloch framework." Journal of Physics: Conference Series 2090, no. 1 (2021): 012082. http://dx.doi.org/10.1088/1742-6596/2090/1/012082.

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Abstract As many molecules have their rotovibrational resonance frequencies in the mid-infrared or terahertz regime, efficient generation of corresponding frequency combs may lead to large progress in gas spectroscopy and sensing. Quantum cascade lasers (QCLs) are among the most promising candidates for a compact and cheap radiation source in this frequency range. This contribution presents a full-wave numerical solution of the Maxwell-Liouville-von Neumann equations, thus avoiding the limited applicability of the rotating wave approximation to moderate field strengths and spectral bandwidths. We include losses and chromatic dispersion of the optically active material in the QCL. The semiclassical approach uses the finite-difference time-domain (FDTD) method to derive update equations for the electric field, starting from the one-dimensional Maxwell equations. There, the optical full-wave propagation is coupled to the electronic quantum system via a polarization term that arises from the evolution of the density matrix. Furthermore, dispersion effects are considered through a classical polarization term and losses are introduced by a finite material conductivity. This work mainly focuses on the integration of group velocity dispersion (GVD) due to the bulk material and, if applicable, the waveguide geometry into the update equations. It is known to be one of the main degradation mechanisms of terahertz frequency combs, but has not yet been added to the existing full-wave solver. The implementation is carried out as Lorentz model and is applied to an experimentally investigated QCL frequency comb setup from the literature. The reported results are in good agreement with the experimental data. Especially, they confirm the need for dispersion compensation for the generation of terahertz frequency combs in QCLs.

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K., G. Tay, K. Tiong W., and Y. Choy Y. "Optical Soliton Simulation by Symmetrized Split Step Fourier Method." International Journal of Trend in Scientific Research and Development 2, no. 6 (2018): 176–80. https://doi.org/10.31142/ijtsrd18410.

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Fiber optic telecommunication gives more benefits if compared to copper wire communication systems, however, group velocity dispersion GVD , fiber loss and also self phase modulation SPM limit the performance of fiber optic telecommunication. When there is a balance between GVD and SPM, there exists a stable wave optical soliton which can propagate for long distance undistorted. In this study, the optical soliton simulation will be carried out using symmetrized split step Fourier method SSFM . K. G. Tay | W. K. Tiong | Y. Y. Choy "Optical Soliton Simulation by Symmetrized Split-Step Fourier Method" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-6 , October 2018, URL: https://www.ijtsrd.com/papers/ijtsrd18410.pdf

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Ghanbari, Ashkan, and Saeed Olyaee. "Highly Nonlinear Composite-Photonic Crystal Fibers with Simplified Manufacturing Process and Efficient Mid-IR Applications." Crystals 13, no. 2 (2023): 226. http://dx.doi.org/10.3390/cryst13020226.

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This paper reveals special design features of the proposed highly nonlinear circular-lattice-silicon-core and silica-doped-with-fluorine (1%) cladding-composite photonic crystal fiber (PCF) in the Mid-infrared region of the spectrum. A region of small negative group velocity dispersion (GVD), managed higher order dispersions (HODs), and unique nonlinearity of silicon have been used to demonstrate a supercontinuum broadening from 1500 nm to 4700 nm with consumption of low input power of 400 W over short fiber distances. It will be also shown that the fiber’s high-level engineered structure finally results in a simple manufacturing process compared with other designed nano-sized silicon PCFs. The designed fiber could have massive potential in gas sensing, soliton effect pulse compression, spectroscopy, material processing, etc.

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Rostami, Ali, and Alireza Andalib. "A PRINCIPAL INVESTIGATION OF THE GROUP VELOCITY DISPERSION (GVD) PROFILE FOR OPTIMUM DISPERSION COMPENSATION IN OPTICAL FIBERS: A THEORETICAL STUDY." Progress In Electromagnetics Research 75 (2007): 209–24. http://dx.doi.org/10.2528/pier07060402.

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Lv, Zhixiao, Jiangbing Du, and Zuyuan He. "On-Chip Multichannel Dispersion Compensation and Wavelength Division MUX/DeMUX Using Chirped-Multimode-Grating-Assisted Counter-Directional Coupler." Photonics 11, no. 2 (2024): 110. http://dx.doi.org/10.3390/photonics11020110.

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On-chip optical dispersion compensation and wavelength division multiplexing/demultiplexing (WDM) are highly demanded functions for optical communications. In this work, we proposed a multichannel dispersion compensation structure based on chirped multimode grating within a counter-directional coupler (CMG-CDC). Simultaneous wavelength division multiplexing and demultiplexing can be realized within a compact footprint. A device design for four-channel CMG-CDC at the C/L (1530–1565 nm) band is presented with a channel spacing of 20 nm assisted by a grooved multimode waveguide structure. The average dispersion for all channels is about −2.25 ps/nm with a channel bandwidth of about 3.1 nm. The device is highly compact and highly scalable, which makes it rather convenient for increasing the group velocity dispersion (GVD) and channel number, indicating flexible applications for versatile systems, including typically coarse wavelength division multiplexer four-lane (CWDM4) transceivers.

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Chai, Jun, Bo Tian, Yu-Feng Wang, Wen-Rong Sun, and Yun-Po Wang. "Conservation Laws and Mixed-Type Vector Solitons for the 3-Coupled Variable-Coefficient Nonlinear Schrödinger Equations in Inhomogeneous Multicomponent Optical Fibre." Zeitschrift für Naturforschung A 71, no. 6 (2016): 525–39. http://dx.doi.org/10.1515/zna-2016-0019.

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AbstractIn this article, the propagation and collision of vector solitons are investigated from the 3-coupled variable-coefficient nonlinear Schrödinger equations, which describe the amplification or attenuation of the picosecond pulses in the inhomogeneous multicomponent optical fibre with different frequencies or polarizations. On the basis of the Lax pair, infinitely-many conservation laws are obtained. Under an integrability constraint among the variable coefficients for the group velocity dispersion (GVD), nonlinearity and fibre gain/loss, and two mixed-type (2-bright-1-dark and 1-bright-2-dark) vector one- and two-soliton solutions are derived via the Hirota method and symbolic computation. Influence of the variable coefficients for the GVD and nonlinearity on the vector soliton amplitudes and velocities is analysed. Through the asymptotic and graphic analysis, bound states and elastic and inelastic collisions between the vector two solitons are investigated: Not only the elastic but also inelastic collision between the 2-bright-1-dark vector two solitons can occur, whereas the collision between the 1-bright-2-dark vector two solitons is always elastic; for the bound states, the GVD and nonlinearity affect their types; with the GVD and nonlinearity being the constants, collision period decreases as the GVD increases but is independent of the nonlinearity.

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Liu, Ye, and Chun Jiang. "Dispersionless one-way slow wave with large delay bandwidth product at the edge of gyromagnetic photonic crystal." International Journal of Modern Physics B 34, no. 10 (2020): 2050086. http://dx.doi.org/10.1142/s0217979220500861.

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We theoretically, demonstrate a high delay bandwidth product (DBP) and zero group velocity dispersion (GVD) in a two-dimensional one-way slow light waveguide. The waveguide consists of gyromagnetic photonic crystal (GMPC) and a cladding formed by silicon photonic crystal. At the edge of the band, weak interactions (“semi-anticrossing”) between the chiral edge state (CES) mode and the mode localized at the surface of cladding are observed. The group velocity of CES wave can be tuned by adjusting the modal field distribution. As a result, an extraordinarily large value of normalized DBP of 0.63 with a group index of 10.32 and a bandwidth ranging from [Formula: see text] to [Formula: see text] is obtained. This result may contribute to one-way slow light applications in information communication systems.

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SOHBATZADEH, F., and S. P. HOSSEINI. "CONTROLLING THE REMOTE IONIZATION DISTANCE BY A LINEARLY CHIRPED FEMTOSECOND LASER PULSE IN AIR." Journal of Nonlinear Optical Physics & Materials 21, no. 04 (2012): 1250046. http://dx.doi.org/10.1142/s0218863512500464.

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In this paper, propagation of a linearly chirped laser pulse in air was investigated to control the remote ionization distance, numerically. Laser spot size and pulse length will be obtained versus effective initial parameters such as positive and negative initial chirp. It is seen that the initial chirp parameter and primary curvature of wave front have important role in focal distance variation and remote ionization. It was also shown that the group velocity dispersion (GVD) could alter and split the positively chirped laser pulse profile after nonlinear self-focusing.

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Atiah Al-Zahy, Younis Mohamed. "A Study of the generation of laser soliton from spontaneous emission by ring cavity with carbon nanotube." Iraqi Journal of Physics (IJP) 12, no. 25 (2019): 25–37. http://dx.doi.org/10.30723/ijp.v12i25.301.

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We demonstrate a behavior of laser pulse grows through fiber laser inside and output cavity with a soliton fiber laser based on the multi-wall carbon nanotube saturable absorber (SA), we investigate the effects of a saturable absorber parameter on the mode-locking of a realistic Erbium fiber ring laser. Generalized nonlinear Schrodinger equation including the nonlinear effects as gain dispersion, second anomalous group velocity dispersion (GVD), self phase modulation (SPM), and two photon absorption used to describe pulse evolution. An analytical method has been used to understand and to quantify the role of the SA parameter on the propagation dynamics of pulse laser. We compute the chirp, power, width and phase of the soliton for range of SA parameters and we studied stability against nonlinear effects at different SA parameter ranges.

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García-Martínez, L., M. Rosete-Aguilar, and J. Garduño-Mejía. "Characterization of ultrashort pulses in the focal region of refractive systems." Acta Universitaria 23 (December 6, 2013): 3–6. http://dx.doi.org/10.15174/au.2013.552.

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In this work we analyze the spatio-temporal intensity of sub-20 fs pulses with a carrier wavelength of 810 nm along the optical axis of low numerical aperture achromatic and apochromatic doublets designed in the IR region by using the scalar diffraction theory. The diffraction integral is solved by expanding the wave number around the carrier frequency of the pulse in a Taylor series up to third order, and then the integral over the frequencies is solved by using the Gauss-Legendre quadrature method. We will show that the third-order group velocity dispersion (GVD) is not negligible for 10 fs pulses at 810 nm propagating through the low numerical aperture doublets, and its effect is more important than the propagation time difference (PTD). For sub-20 fs pulses, these two effects make the use of a pulse shaper necessary to correct for second and higher-order GVD terms and also the use of apochromatic optics to correct the PTD effect.

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Esther Lidiya, A., R. Vasantha Jayakantha Raja, and Shailendra K. Varshney. "Low pedestal sub-17 fs pulse generation through cascaded self-similar compression in photonic crystal fibers." Journal of Optics 23, no. 12 (2021): 125503. http://dx.doi.org/10.1088/2040-8986/ac34e8.

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Abstract We propose a realistic numerical model based on cascaded self-similar pulse compression to generate low pedestal ultrashort pulses at 2.5 µm. Self-similarity in photonic crystal fibers (PCFs) has been attained by modelling exponentially dispersion decreasing and exponentially nonlinearity increasing chalcogenide PCFs. The tapered PCF (TPCF) model is theoretically designed using the fully vectorial effective index method (FVEIM) to obtain accurate effective refractive index, group velocity dispersion (GVD), and Kerr nonlinearity values with low computation time. Initially, fundamental soliton compression in As2S3 tapered PCF is being investigated for the pedestal-free reduction of the pulse width. Subsequently, the compression factor is further enhanced in the As2Se3 PCF-based nonlinear optical loop mirror. The numerical outcomes reveal a compression of 1 ps pulse down to a pulse width of 16.6 fs with a peak power of 116 W in a total fiber length of L = 61 cm.

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K.G., Tay, and Tiong W.K. "Method of Line Solution of Optical Soliton in Optical Communication System." Journal of Engineering and Science Research 6, no. 6 (2022): 79–83. http://dx.doi.org/10.26666/rmp.jesr.2022.6.7.

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The performance of fiber-optic communication is constrained by the dispersive phenomenon of group velocity dispersion (GVD) and fiber non-linearity of self-phase modulation, but when these effects are balanced, a single wave or soliton is produced. A soliton can travel a great distance with constant speed. It is suitable for use in ultra-long-distance communication because of these unique features. The non-linear Schrodinger (NLS) equation describes the optical soliton propagation in optical fibers. By using the method of line (MOL) to solve the NLS equation, this study mimics the optical soliton propagation. It demonstrates that during simulations at 400 km, the optical soliton maintains its shape and amplitude.

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Al-Dergazly, Anwaar A. "Investigation of dispersion and nonlinear characteristics of liquid core optical fiber filled with olive oil." Sustainable Engineering and Innovation 2, no. 1 (2020): 34–40. http://dx.doi.org/10.37868/sei.v2i1.102.

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This paper introduces a prospective material for photonic laser applications. Different high purity samples of olive oil were subjected to spectrophotometer to determine the absorption spectra. The transmission behavior of olive oil is about (44.28) % at wavelength of 532 nm, while it is (62.94) % at 1064 nm. Then, the nonlinear optical properties represented by nonlinear refractive index and nonlinear absorption coefficient are determined using a highly sensitive method known as Z-scan technique. Z-Scan experiment was performed using a 1064 nm CW Nd:YAG and 532 nm SHG Nd:YVO4 lasers. n2 = 3.99×10-6W/cm2 and beta = -0.0017 m/W for 1064nm wavelength and n2 = 2.45×10-7W/cm2 and beta =-7.26×10-4 m/W for 532nm wavelength. This paper gives simulation results for a liquid core optical fiber (LCOF) filled with olive oil. The nonlinear propagation constant and group velocity dispersion (GVD) properties are estimated. The simulation of generation of LCOF is also obtained. The calculations show that LOCF can provide huge nonlinear parameter and large span of slow varying GVD characteristics in the visible and infrared region, which have potential applications in optical communications and nonlinear optics. The material is olive oil which is classified as organic compound, having a good nonlinear optical properties making it a potential candidate to be for photonic applications.

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Manjeet, Bagri, and Kumar Suresh. "Solitons transmission system: A dynamic shift in optical fiber communication." Indian Journal of Science and Technology 13, no. 30 (2020): 3093–102. https://doi.org/10.17485/IJST/v13i30.384.

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Abstract Objective: To present a detailed study of Solitons transmission system,including their types, applications, effects, and updated research work and research gaps. Findings: The 4th, generation fiber optic communication system utilizes visual amplification to decrease the demand for repeaters and WDM to increase the information power. Similarly, 5th the phase of Optical Fiber Communication is now expending the distances range which the wavelength division multiplexing system will control. The traditional wave length frame called the C ring covers the distance range 1.53 to 1.57 um and dry material has the low loss window promising extension of range to 1.30 to 1.65 um. Additional development includes the idea of visual solitons pulses that maintain their body by counteracting the results of distribution with nonlinear effects of this material by applying pulses of specific shape. Application: This will motivate the researchers to undertake research work in the field of Solitons communication to achieve improved design characteristics, reducing number of repeaters, cost and higher data rate transmissions. Keywords: Inter Symbol Interference (ISI); Group Velocity Dispersion (GVD);Self-Phase Modulation (SPM); WDM; OFDM

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Ghanbarisabagh, Mohammad, Nasreddine Maloulki, and Bechir Nsiri. "Efficiency Improvement for Optical OFDM Systems." International Journal of Information and Communication Sciences 1, no. 2 (2016): 35–38. http://dx.doi.org/10.11648/j.ijics.20160102.14.

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The evaluation of Optical Orthogonal Frequency Division Multiplexing (OOFDM) using Least Mean Square Time-domain Equalizer (LMSTE), Recursive Least Squares-Time-domain Equalizer (RLSTE) and Decision Feedback Time-domain Equalizer (DFTE) to reduce Cyclic Prefix (CP) length over 1200 Km of Standard Single Mode Fiber (SSMF) is presented. All of these TEQs are used immediately after the fiber channel. They can cancel the residual Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI) caused by both the Group Velocity Dispersion (GVD) and the CP length being shorter than the Channel Impulse Response (CIR). Using these TEQs allow the reduction in size of CP, and consequently leading to system performance improvement. DFTE can decrease the noise whereas RLSTE can achieve a higher convergence and better performance compared to LMSTE.

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Lobanov, V. E. "Vliyanie nagreva na generatsiyu i svoystva platikonov v vysokodobrotnykh opticheskikh mikrorezonatorakh." Журнал экспериментальной и теоретической физики 164, no. 5 (2023): 701–14. http://dx.doi.org/10.31857/s0044451023110019.

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Pumping a high-Q optical microresonator by an external laser is inevitably associated with thermal effects. They have a significant impact on the dynamics of nonlinear processes in such structures, including the generation of optical frequency combs and dissipative solitons. The generation process and the properties of bright solitons in such heated microresonators with anomalous group velocity dispersion (GVD) have been well studied, and a number of methods have been developed to minimize the effect of thermal processes. However, for dark solitons or platicons excited at normal GVD, these issues have been studied significantly less. In this work, the properties of platicons in heated microresonators are analyzed, and it is shown that in the case of “positive” thermal effects, when the direction of the thermal shift of the resonance frequencies of a microresonator coincides with the direction of the nonlinear shift, the widest high-energy platicons with the duration close to the round trip time in the resonator are stable. In the case of “negative” thermal effects, narrow low-energy platicons remain stable. Moreover, in microresonators with “negative” thermal effects, the interaction between cubic nonlinear and thermal processes can ensure the generation of platicons without special techniques required in other cases.

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Abd El-Mottaleb, Somia, Heba Fayed, Ahmed Abd El-Aziz, Mohamed Metawee, and Moustafa Aly. "Enhanced Spectral Amplitude Coding OCDMA System Utilizing a Single Photodiode Detection." Applied Sciences 8, no. 10 (2018): 1861. http://dx.doi.org/10.3390/app8101861.

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In this paper, the performance of a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) system is investigated utilizing a single photodiode (SPD) detection technique. The proposed system uses enhanced double weight (EDW) codes as signature codes with three simultaneous users to overcome both phase-induced intensity noise (PIIN) and multiple access interference (MAI). In addition, a dispersion compensating fiber (DCF) is used in order to decrease the group velocity dispersion (GVD) caused in the single mode fiber. An erbium-doped fiber amplifier (EDFA) is used to overcome the attenuation. The use of both DCF and EDFA leads to an appreciable enhancement in the system performance. The system performance is evaluated through its bit error rate (BER), Q-factor, and received power. A comparison between the EDW codes and modified double weight (MDW) codes on the SAC-OCDMA system is demonstrated. Simulation is carried out through Optisystem ver. 7. The simulation results show that: (a) using an avalanche photodiode (APD) over PIN photodiode allows data transmission over longer distances; (b) the use of DCF improves the system BER;(c) using MDW codes gives better BER than using EDW codes.

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TANG Di, CHEN Tianci, KANG Zhaofeng, et al. "Dispersion control based on gradient refractive index microresonators." Acta Physica Sinica 74, no. 6 (2025): 0. https://doi.org/10.7498/aps.74.20241803.

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Kerr optical frequency combs based on whispering-gallery mode (WGM) microresonators have great potential for applications in various fields such as precision measurement, spectral analysis, optical communication, and quantum technology. The interaction between dispersion and nonlinearity is crucial for determining the stability and bandwidth performance of optical frequency combs. In particular, the Kerr bright soliton optical frequency comb requires a suitable anomalous group velocity dispersion (GVD) to maintain the dissipative system. Therefore, designing the dispersion of the WGM microresonator is essential for generating the Kerr optical frequency comb. However, WGM microresonators typically have normal and fixed material dispersion, and their dispersion design is primarily based on modulating the mode field distribution by changing the microresonator structure to achieve anomalous dispersion, which offers limited flexibility. In this paper, we introduce a radially distributed gradient refractive index n(r) into WGM microresonators and propose using the refractive index profile to control the dispersion of gradient-index (GRIN) microresonators. Numerical simulations and finite element analysis demonstrate that the refractive index gradient constrains the mode field, pushing it away from the cavity edge, resulting in near-zero geometric dispersion in the GRIN microresonator.Two dispersion modulation methods are explored: modifying the microresonator’s geometric shape and constructing a dual potential well. The effects of microresonator radius, wedge angle, ion diffusion sequence, and potential well width and spacing on dispersion are systematically investigated. Simulation results show that both methods can achieve a wide range of anomalous dispersion within the communication band. In the first method, mode field leakage in the bilateral wedge-shaped GRIN microresonator produces anomalous dispersion, while no leakage results in normal dispersion. When the mode field is pushed away from the edge, near-zero dispersion is achieved. In the second method, energy coupling between the inner and outer modes in the dual potential well structure leads to anomalous dispersion in the inner mode and normal dispersion in the outer mode. Our findings highlight the flexibility of GRIN microresonator dispersion control, offering great potential for nonlinear optical applications.

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36

Fakhriy, Hario, Maulana Eka, Suyono Hadi, N. Hasanah Rini, and H. Pramono Sholeh. "Impact of Combine Dithering and Modulators to Mitigate Noise in Radio Over Fiber System." Indonesian Journal of Electrical Engineering and Computer Science 12, no. 1 (2018): 428–32. https://doi.org/10.11591/ijeecs.v12.i1.pp428-432.

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A well-prepared Radio over Fiber (RoF) is a technology that combines two transmission technologies, radio and optical fiber transmissions. The study focused on the characteristics and problems of the optical fiber medium. One of the problems in the optical fiber is the effect of nonlinear characteristic, which caused by the high light intensity in the optical fiber core with extended interaction area in a single mode fiber (SMF). This characteristic reduces the output width and creates a pulse broadening. The nonlinear characteristics discussed in this study focused on SPM (self-phase modulation) and GVD (Group Velocity Dispersion). To overcome the nonlinear problems, this study presented a method to make the noise-resistant transmitted signal and improve the optical fiber power range. The fundamental of this study was developing similarities of previous studies regarding nonlinearity in the optical fiber. The results show that the use of two modulators combined with the amplification generated the signal with smoother spectrum, which means that the spectrum distribution was more uniform. There was 61.5 % increase of the peak power of the output signal after amplification using an optical amplifier.

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37

Xie, Tingting, Pengwei Gong, Xiaohe Cheng, Tao Xiu, and Yuan Yao. "An Ultra-Broadband Conductor-Backed Coplanar Waveguide with Sine Edges." Sensors 24, no. 20 (2024): 6640. http://dx.doi.org/10.3390/s24206640.

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In this paper, a conductor-backed coplanar waveguide with sine edges (CBCPW-SE), consisting of a conductor-backed coplanar with periodic sine edges supported by a dielectric substrate, is proposed as a promising new transmission line (TL) at millimeter-wave and terahertz frequencies. This configuration offers a distinct advantage by maintaining a constant input impedance of 50 Ω across a broad frequency spectrum, eliminating the necessity for any additional impedance matching transitions, thereby enhancing the overall efficiency and simplicity of the transmission system. To verify the design, the CBCPW-SE was fabricated and measured. The measurement results demonstrate that, from 10 MHz to 100 GHz, the insertion loss is less than 0.1 dB/mm and the reflection coefficient is better than −10 dB. The measured S21 (dB) for a 50 mm-long CBCPW-SE section is less than −5 dB from 10 MHz to 100 GHz. The measured group delay per unit length of the trace is 3.4–5 ps, ranging from 10 MHz to 100 GHz. Moreover, the measured group velocity dispersion (GVD) approaches zero, signifying the minimal temporal spreading of the signal components, a crucial aspect for maintaining signal integrity and facilitating high-speed data transmission.

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38

Hario, Fakhriy, Eka Maulana, Hadi Suyono, Rini N. Hasanah, and Sholeh H. Pramono. "Impact of Combine Dithering and Modulators to Mitigate Noise in Radio Over Fiber System." Indonesian Journal of Electrical Engineering and Computer Science 12, no. 1 (2018): 428. http://dx.doi.org/10.11591/ijeecs.v12.i1.pp428-432.

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A well-prepared Radio over Fiber (RoF) is a technology that combines two transmission technologies, radio and optical fiber transmissions. The study focused on the characteristics and problems of the optical fiber medium. One of the problems in the optical fiber is the effect of nonlinear characteristic, which caused by the high light intensity in the optical fiber core with extended interaction area in a single mode fiber (SMF). This characteristic reduces the output width and creates a pulse broadening. The nonlinear characteristics discussed in this study focused on SPM (self-phase modulation) and GVD (Group Velocity Dispersion). To overcome the nonlinear problems, this study presented a method to make the noise-resistant transmitted signal and improve the optical fiber power range. The fundamental of this study was developing similarities of previous studies regarding nonlinearity in the optical fiber. The results show that the use of two modulators combined with the amplification generated the signal with smoother spectrum, which means that the spectrum distribution was more uniform. There was 61.5 % increase of the peak power of the output signal after amplification using an optical amplifier.

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39

MENEZES, J. W. M., J. R. R. SOUSA, M. B. C. COSTA, et al. "NUMERICAL ANALYSIS OF THE INSTANTANEOUS AND RELAXED KERR MODEL FOR GENERATION OF THE ALL-OPTICAL LOGIC GATES WITH TRIANGULAR FIBER COUPLER (TFC)." Journal of Nonlinear Optical Physics & Materials 21, no. 03 (2012): 1250037. http://dx.doi.org/10.1142/s0218863512500373.

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All-optical logic gates can enable many advanced functions such as all-optical bit-pattern recognition, all-optical bit-error rate monitoring, all-optical packet address and payload separation, all-optical label swapping and all-optical packet drop in optical time domain multiplexing (OTDM) networks. Recently, much attention has been given to the influence of the relaxation process (sometimes called the Debye relaxation model) of the nonlinear response because the usual assumption of instantaneous nonlinear response fails for ultrashort pulses and additional contributions coming from nonlinear dispersion and relaxed nonlinearity have to be taken into account. The Kerr–Debye model is a relaxation of the nonlinear Kerr model in which the relaxation coefficient is a finite response time of the nonlinear material. In this paper, we have presented a numerical analysis of the triangular fiber coupler (TFC) for generation of the all-optical logic gates with nonlinear optical (NLO) properties, where we consider the nonlinear effects Kerr group velocity dispersion (GVD) and self-phase modulation (SPM) instantaneous and relaxed (Kerr–Debye model). To implement all-optical logic gates we used TFC of three symmetric configurations [Instantaneous (III), Relaxed (RRR-5 and RRR-9)]. In the instantaneous condition, the TFC is made up of silica optical fibers (with instantaneous response time — indicated by III) and in the relaxed conditions (RRR-5 and RRR-9) the TFC is made up of fibers with delayed response time of around 25 ps (for example, the polymer optical fibers). In our paper, we are interested in the transmission characteristics, the XRatio level (XR (dB)) as a function of the ΔΦ parameter, the normalized time duration (NTD) and the pulse evolution along the TFC and finally to compare the performance of all-optical logic gates, we will use the figure-of-merit of the logic gates (FOMELG (dB)) defined as a function of the extinction ratio of the gate outputs. All results were obtained numerically, considering a very simple model for generation of a optical logic gates.

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Ntemka, Aikaterini, Ioannis Tsakmakidis, Constantin Boscos, Alexandros Theodoridis, and Evangelos Kiossis. "The Role of Ewes’ Udder Health on Echotexture and Blood Flow Changes during the Dry and Lactation Periods." Animals 12, no. 17 (2022): 2230. http://dx.doi.org/10.3390/ani12172230.

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The objective of the current study was to investigate the echotextural and hemodynamic changes of ewes entering the dry period with or without subclinical mastitis. B-mode and color Doppler ultrasonography were applied to 12 Chios ewes (6 with healthy udders (group A) and 6 with subclinical mastitis (group B)) before the dry period, during the dry period (the involution phase, steady state, and transition phase), and postpartum. The color Doppler of the mammary arteries was used to evaluate them according to the pulsatility index (PI), resistive index (RI), end-diastolic velocity (EDV), time-averaged maximum velocity (TAMV), blood flow volume (BFV), and artery diameter (D). Udder parenchyma images, analyzed by Echovet v2.0, were used to evaluate the mean value (MV), standard deviation (SD), gradient mean value (GMV), gradient variance (GV), contrast (Con), entropy (Ent), gray value distribution (GVD), run length distribution (RunLD), and long run emphasis (LRunEm). In the involution phase, the PI was higher in group B compared to group A (p ≤ 0.05). The PI and RI were higher postpartum, whereas the EDV, TAVM, and D were higher in the transition phase (p ≤ 0.05). Neither the period nor the ewe group affected the MV, SD, GMV, GV, Con, and GVD values (p ≤ 0.05). In the steady state, the LRunEm was higher in group B, but postpartum, it was higher in group A (p ≤ 0.05). In conclusion, B-mode and Doppler can reveal differences (i) between healthy ewes and ewes with subclinical mastitis and (ii) among the different periods studied. Further research is needed on the blood flow and echotexture indices of the udders of ewes with unilateral subclinical mastitis.

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41

Schober, C. M., and T. H. Wlodarczyk. "Dispersion, group velocity, and multisymplectic discretizations." Mathematics and Computers in Simulation 80, no. 4 (2009): 741–51. http://dx.doi.org/10.1016/j.matcom.2009.08.015.

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42

Zarattini, S., J. A. L. Aguerri, A. Biviano, M. Girardi, E. M. Corsini, and E. D’Onghia. "Fossil group origins." Astronomy & Astrophysics 631 (October 11, 2019): A16. http://dx.doi.org/10.1051/0004-6361/201834689.

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Aims. We aim to study how the velocity segregation and the radial profile of the velocity dispersion depend on the prominence of the brightest cluster galaxies (BCGs). Methods. We divided a sample of 102 clusters and groups of galaxies into four bins of magnitude gap between the two brightest cluster members. We then computed the velocity segregation in bins of absolute and relative magnitude. Moreover, for each bin of magnitude gap we computed the radial profile of the velocity dispersion. Results. When using absolute magnitudes, the segregation in velocity is limited to the two brightest bins and no significant difference is found for different magnitude gaps. However, when we use relative magnitudes, a trend appears in the brightest bin: the larger the magnitude gap, the larger the velocity segregation. We also show that this trend is mainly due to the presence, in the brightest bin, of satellite galaxies in systems with small magnitude gaps: in fact, if we study central galaxies and satellites separately, this trend is mitigated and central galaxies are more segregated than satellites for any magnitude gap. A similar result is found in the radial velocity dispersion profiles: a trend is visible in central regions (where the BCGs dominate) but, if we analyse the profile using satellites alone, the trend disappears. In the latter case, the shape of the velocity dispersion profile in the centre of the systems with different magnitude gaps shows three types of behaviour: systems with the smallest magnitude gaps have an almost flat profile from the centre to the external regions; systems with the largest magnitude gaps show a monothonical growth from the low values of the central part to the flat ones in the external regions; and finally, systems with 1.0 < Δm12 ≤ 1.5 show a profile that peaks in the centre and then decreases towards the external regions. Conclusions. We suggest that two mechanisms could be responsible for the observed differences in the velocity segregation of the BCGs: an earlier formation of systems with a larger magnitude gap or a more centrally concentrated halo. However, the radial profiles of the velocity dispersion confirm that central galaxies are more relaxed, but that the satellite galaxies do not seem to be affected by the magnitude gap.

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43

Dienes, Andrew, Youhang Peng, and Andre Knoesen. "Group velocity dispersion in asymmetric slab guide." Applied Optics 28, no. 1 (1989): 12. http://dx.doi.org/10.1364/ao.28.000012.

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Jiang, Wei C., and Qiang Lin. "Tuning group-velocity dispersion by optical force." Optics Letters 38, no. 14 (2013): 2604. http://dx.doi.org/10.1364/ol.38.002604.

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45

Yu-zhen, Shen, Xing Qi-rong, Shi Ji-ying, and Wang Qing-yue. "Group-velocity dispersion in chirped-pulse amplifier." Acta Physica Sinica (Overseas Edition) 5, no. 10 (1996): 769–80. http://dx.doi.org/10.1088/1004-423x/5/10/007.

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46

Mogilevtsev, D., T. A. Birks, and P. St J. Russell. "Group-velocity dispersion in photonic crystal fibers." Optics Letters 23, no. 21 (1998): 1662. http://dx.doi.org/10.1364/ol.23.001662.

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Haus, Hermann A. "Group velocity, energy, and polarization mode dispersion." Journal of the Optical Society of America B 16, no. 11 (1999): 1863. http://dx.doi.org/10.1364/josab.16.001863.

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Sakai, Jun-Ichi, and Kazuki Kuramitsu. "Group-velocity dispersion in a Bragg fiber." Journal of the Optical Society of America B 25, no. 3 (2008): 414. http://dx.doi.org/10.1364/josab.25.000414.

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Matsko, A. B., A. A. Savchenkov, and L. Maleki. "Normal group-velocity dispersion Kerr frequency comb." Optics Letters 37, no. 1 (2011): 43. http://dx.doi.org/10.1364/ol.37.000043.

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Wang, Lifeng, Wanlin Guo, and Haiyan Hu. "Group velocity of wave propagation in carbon nanotubes." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2094 (2008): 1423–38. http://dx.doi.org/10.1098/rspa.2007.0349.

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The group velocities of longitudinal and flexural wave propagations in single- and multi-walled carbon nanotubes are studied in the frame of continuum mechanics. The dispersion relations between the group velocity and the wavenumber for flexural and longitudinal waves, described by a beam model and a cylindrical shell model, are established for both single- and multi-walled carbon nanotubes. The effect of microstructures in carbon nanotubes on the wave dispersion is revealed through the non-local elastic models of a beam and a cylindrical shell, including the second-order gradient of strain and a parameter of microstructure. It is shown that the microstructures in the carbon nanotubes play an important role in the dispersion of both longitudinal and flexural waves. In addition, the non-local elastic models predict that the cut-off wavenumber of the dispersion relation between the group velocity and the wavenumber is approximately 2×10 10 m −1 for the longitudinal and flexural wave propagations in both single- and multi-walled carbon nanotubes. This may explain why the direct molecular dynamics simulation cannot give a proper dispersion relation between the phase velocity and the wavenumber when the wavenumber approaches approximately 2×10 10 m −1 , much lower than the cut-off wavenumber for the dispersion relation between the phase velocity and the wavenumber predicted by continuum mechanics.

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Journal articles on the topic 'Group Velocity Dispersion (GVD)'

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