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Dissertations / Theses on the topic 'Multi Quantum well lasers'

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Published: 4 June 2021

Last updated: 8 February 2022

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1

RAJASEKARAN, RAJASUNDARAM. "Dependence of LASER Performance on Number of Quantum Wells InAIGaAs Semiconductor LASERS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155791964.

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2

Prosyk, Kelvin. "Power and spectral characterization of InGaAsP-InP multi-quantum well lasers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0008/NQ42759.pdf.

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3

Jones, Brynmor Edward. "ZnCdMgSe and AlGalnP multi-quantum well films for colour conversion and optically-pumped visible lasers." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25448.

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II-VI semiconductor material ZnCdMgSe has the potential to enable optical devices emitting throughout the visible spectrum. While difficulties in doping of this material have hindered its development for conventional electrically-injected semiconductor lasers, the recent availability of efficient, high power InGaN-based laser diodes has created the opportunity for optically-pumped devices, and this work primarily focusses on the progression towards realising vertical external-cavity surface-emitting lasers (VECSELs) based on this material system. Challenges in the growth of a ZnCdMgSe distributed Bragg reflector (DBR), such as low refractive index contrast and limited growth thickness for maintaining material quality, lead to the design of novel thin-film VECSEL structures, and the development of epitaxial transfer techniques to overcome the absorptive InP growth substrate and buffer. Transfer of thin-film (few microns thick) multi-quantum well heterostructures is demonstrated for samples with areas of a few mm², successfully transferring and liquid-capillary-bonding the films to diamond heat-spreaders for thermal management. Continued challenging growth, namely heterostructure layer inaccuracies, mean that laser threshold is not yet reached, however extensive characterisation and analysis is carried out to inform future progress in realising the ZnCdMgSe thin-film VECSEL. The thin-film VECSEL architecture offers advantages beyond allowing for the use of novel materials, opening the potential for novel laser cavities and optical pumping schemes. The thin-film transfer method developed for the II-VI VECSEL is adapted for the transfer of III-V AlGalnP epitaxial structures from GaAs growth substrates, and AlGalnP thin-film VECSELs are demonstrated operating continuous wave at red wavelengths at room temperature. Laser operation is currently limited by pump-induced de-bonding from the diamond, with attempts made to counter this through the refinement of structre design (including strain balancing) and transfer method. Until thermal rollover occurs, performance is relatively comparable with the 'conventional'; gain-mirror AlGaInP VECSELs, with a maximum output power of 21 mW recorded at both 682 nm and 670 nm for low output coupling. Using the transfer method developed for the II-VI material, ZnCdMgSe multi-quantum well structures are used as colour conversion films for micron-size LED arrays. The resulting hybrid devices are demonstrated to have high modulation bandwidths, limited only by the LED modulation bandwidth, suitable for application in visible-light communication.

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4

Marinelli, Claudio. "Techniques for improved-performance InGaN multi-quantum-well laser diodes." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369525.

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5

Sindile, Pia. "Probing the dynamic behaviour of ridge waveguide multi-quantum well distributed feedback lasers, fundamental picosecond studies of chirp under large-signal modulation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ63028.pdf.

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6

Weetman, Philip. "Modelling Quantum Well Lasers." Thesis, University of Waterloo, 2002. http://hdl.handle.net/10012/1262.

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In this thesis, two methods to model quantum well lasers will be examined. The first model is based on well-known techniques to determine some of the spectral and dynamical properties of the laser. For the spectral properties, an expression for TE and TM modal amplitude gain is derived. For the dynamical properties, the rate equations are shown. The spectral and dynamical properties can be examined separately for specific operating characteristics or used in conjunction with each other for a complete description of the laser. Examples will be shown to demonstrate some of the analysis and results that can be obtained. The second model used is based on Wigner functions and the quantum Boltzmann equation. It is derived from general non-equilibrium Greens functions with the application of the Kadanoff-Baym ansatz. This model is less phenomenological than the previous model and does not require the separation of physical processes such as the former spectral and dynamical properties. It therefore has improved predictive power for the performance of novel laser designs. To the Author's knowledge, this is the first time such a model has been formulated. The quantum Boltzmann equations will be derived and some calculations will be performed for a simplified system in order to illustrate some calculation techniques as well as results that can be obtained.

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7

Lyubomirsky, Ilya. "Toward far infrared quantum well lasers." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80484.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.
Includes bibliographical references (p. 113-121).
by Ilya Lyubomirsky.
Ph.D.

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8

Griffin, Peter Stephen. "Multicontact, quantum well lasers for lightwave communication." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283927.

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9

Walker, Craig Lee. "Quantum well intermixing for high brightness semiconductor lasers." Thesis, University of Glasgow, 2002. http://theses.gla.ac.uk/4019/.

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The research presented in this thesis describes how monolithic opto-electronic integration using quantum well intermixing (QWI) can be applied to improve the high brightness performance of single-mode ridge waveguide GaAs/AlGaAs quantum well (QW) lasers. The sputtered SiO2 QWI technique is explained, and a selective process suitable for device manufacture was demonstrated. This QWI technology was applied to create three distinct devices to address the performance limitations imposed by catastrophic optical damage (COD), spatial mode instability, and overheating. A non absorbing mirror (NAM) laser technology was successfully demonstrated, capable of significantly improving the COD level of high power lasers prone to mirror degradation. Under pulsed test conditions designed to induce COD, the standard ridge laser suffered COD at 230 mW/facet, compared to 600 mW/facet for the NAM laser, demonstrating an improved COD level by a factor of 2.6. Confirmation of the COD failure mechanism was achieved by facet inspection, and removal of the damaged facets. Successful demonstration of a high brightness single lateral mode ridge laser with a self-aligned buried heterostructure defined by QWI was achieved. The device benefits from de-coupling of the optical and electrical confinement, allowing enhanced fundamental lateral mode operation up to higher powers; the buried heterostructure improves the lateral mode discrimination, thus suppressing higher order modes. Comparison of the standard ridge laser and the buried heterostructure ridge laser for ridge widths of 5 mm clearly demonstrated the improvement gained; the standard ridge laser was too wide to operate in the fundamental mode, whereas the buried heterostructure ridge laser showed dominantly single-mode operation up to 130 mW/facet.

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10

Fehse, Robin. "Recombination processes in GaInAs/GaAs semiconductor quantum-well lasers." Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/677/.

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11

Mazzucato, Simone. "GaInNAs/GaAs quantum well structures for uncooled 1.3mum lasers." Thesis, University of Essex, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275858.

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12

Eng, Lars E. Yariv Amnon Yariv Amnon. "Low threshold current strained InGaAs/AlGaAs quantum well lasers /." Diss., Pasadena, Calif. : California Institute of Technology, 1993. http://resolver.caltech.edu/CaltechETD:etd-08272007-091655.

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13

Tan, Hock Aun. "Towards multiple quantum well optically pumped far infrared lasers." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/46104/.

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Optically pumped lasers based on GaAs/AlGaAs multiple quantum well (MQW) structures are a potential coherent source in the far infrared (FIR) wavelengths. The FIR (~ 30 to 300 μm) is a region within the electromagnetic spectrum that has seen relatively little development. No practical solid-state lasers have been possible in the FIR, which is also referred to as the terahertz (THz) wave, until the very recent demonstration of THz quantum cascade lasers. Other existing FIR lasers are either bulky, expensive, or require magnetic fields for operation. Hence, progress in the FIR depends on the availability of compact, miniature, and inexpensive FIR sources. Optically pumped MQW lasers have advantages in simplicity of design, device processing, and lower free carrier loss, as compared to the electrically pumped lasers. Unlike traditional semiconductor lasers, the FIR MQW lasers involve only electron transitions between subbands of the conduction band. These subband energy levels in our stepped quantum well (QW) design can be tailored by selectively changing the thickness and alloy composition of the QW layers. However, electrons must first be confined to the subbands by doping of the MQW structure. Instead of placing the dopants at the middle of the barrier, the MQW is doped at the stepped well edge to minimise the parasitic distortion to the QW energy profile. FIR photoluminescence signal has been observed in a QW structure doped in the stepped well edge. Electron lifetime measurements were also conducted using a free electron laser (FELIX). Intersubband lifetimes of the order of few ps were obtained in the pump-probe experiment, which were longer than reported values for rectangular QWs. Moreover, a sub-ns slow decay due to multi-photon absorption was observed at high pump intensities. A rate equation model agreed well with the experimental result. A novel idea of stacking two MQW slabs face-to-face to improve the mode confinement of the laser system has been proposed. Possible errors in aligning the slabs were modelled, where the estimated increase in diffraction loss suggested that the stacking scheme is highly practical. Together with embedded heavily doped layers in the MQW structures, which utilise the surface plasmon guiding effects, a low modal loss and high mode confinement structure can be achieved. FIR optical signal systems were also studied, where detectors and optical materials required are different to those in the shorter wavelengths region. An optically pumped methanol gas laser was also built and tested for the work as an alternative FIR source.

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14

Fleischmann, Thomas. "Piezoelectric strained layer semiconductor lasers and integrated modulators." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251310.

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15

Tandoi, Giuseppe. "Monolithic high power mode locked GaAs/AlGaAs quantum well lasers." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2721/.

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In this thesis, approaches for increasing the output power in monolithically integrated semiconductor mode locked (ML) lasers were investigated. The wavelength range considered is the range of operation of low temperature grown GaAs photomixers, devices commonly used for THz generation. In particular, two GaAs/AlGaAs quantum well laser epistructures (operating at 830 nm and 795 nm) were considered, both with reduced optical confinement and elongated vertical optical mode size. In this work, such laser epistructures, commonly used by high power semiconductor laser manufacturers, were successfully employed, for the first time, for producing passively ML devices. Improved average powers (up to 48 mW) under ML operation were demonstrated, around ten times higher than values previously reported in monolithic GaAs/AlGaAs ML lasers. In continuous wave operation, the output power was limited by the catastrophic damage of the laser facets at around 50 mW. For this reason, facet passivation techniques were investigated, allowing for powers up to 124 mW to be achieved. In ML regime, the output power was instead limited by the catastrophic damage of the reverse biased section of the laser. This failure mechanism was investigated and explained considering thermal effects on the reverse biased section. Such effects limited the output power to around 27 mW in 830 nm devices, which was then improved by 70% in 795 nm devices with a 70% larger optical mode area. The larger mode size, combined to a small duty-cycle laser geometry, enabled a record peak power of 9.8 W to be achieved at 6.83 GHz. This particular repetition rate was specifically designed for coherent population trapping experiments in 87Rb vapors. Sub-picosecond transform limited pulses were achieved in both the laser materials considered, with a minimum duration of 0.43 ps at 126 GHz. With the values of peak power achieved, the developed devices may also be directly used for two-photon microscopy applications.

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16

Qiu, Yingning. "Investigation of disorder effects on dilute nitride quantum well lasers." Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443272.

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17

Seltzer, Colin Phillip. "Indium phosphide based multiple quantum well lasers : physics and applications." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/844392/.

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Multiple quantum well lasers based on the III-V compound semiconductor indium phosphide were studied in this thesis. Systematic investigations were carried out on the effects of quantisation and strain on the temperature sensitivity of threshold current, modulation properties, external cavity operation and the 'gain lever' effect. Trends in the temperature sensitivity of threshold current for lasers of various lengths and quantum well numbers can be understood in terms of the nonlinear gain-current density relation. However, compared to bulk active region devices there was no significant improvement. It is unclear at present whether this is due to the temperature sensitivity of optical gain or Auger recombination. Relative intensity noise measurements were used to compare the modulation properties of lattice-matched and strained MQW lasers. This method gives an estimate of the differential gain and was used to study the properties of devices which were unsuitable for high speed applications. These measurements showed that gain saturation and carrier transport effects may be significant in certain laser structures. Band-filling effects due to the reduced volume and modified density of states were utilised in the demonstration of a grating external cavity laser operating across the 1.3 mum optical fibre window. This configuration results in single-mode operation across the gain spectrum of the laser. High output power was exhibited across a wide tuning range. The 'gain lever' effect uses the nonlinear gain-current density relation to enhance the amplitude modulation efficiency and the signal-to-noise-ratio. MQW and bulk devices of different length and split ratio were compared. It was seen experimentally and numerically that the nonlinearity causing this effect also increases the distortion. Finally, it is discussed that further modifications to laser properties may be seen in active regions incorporating quantum wires and boxes.

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18

Xu, Bin 1968. "Development of intersubband terahertz lasers using multiple quantum well structures." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/49673.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
Includes bibliographical references (p. 221-241).
This thesis describes an experimental and theoretical effort in developing intersubband THz lasers using multiple-quantum-well structures. Scarcity of compact solid state sources in this frequency range, and to demonstrate a novel unipolar laser technology, motivated this research. Transport studies for realizing THz intersubband population inversion, new methods for long-wavelength mode confinement, and farinfrared spectral measurement techniques are critical steps in achieving this goal. Conduction-band three-level subband systems in triple-quantum-well structures using GaAs/Alo.3Gao.7As heterostructures were proposed, designed, and simulated by a numerical method. The numerical simulation is a self-consistent solution among the Schrödinger equation, Poisson equation, and rate equations. Electrons are injected by resonant tunneling to populate the upper subband; the lower subband is depopulated by fast longitudinal optical (LO) phonon scattering. THz emission devices consist of many modules of such triple-quantum-structures with the three-level systems cascade connected to each other. Dynamic charge of electron is provided by the 6-doping per module. Temperature-dependent intersubband scattering plays a key role in transport modeling and therefore the degree of population inversion. Systematic calculations were performed to address issues of hot electron effect, lattice heating, and non-equilibrium optical phonons. Guidelines for device design and optimization were provided. The measured dc I-V at cryogenic temperature confirmed the design expectations. Plasma confinement is used for making THz laser cavities. The minimum cavity loss can only be achieved by using metallic waveguides. The first metallic waveguide, which incorporates non-alloyed ohmic contact, was successfully fabricated by combining wafer bonding and selective etching techniques. Schemes for THz emission couplings were investigated by quantifying coupling loss, including surface coupling by gratings and edging coupling by facets. The first free-space THz spectral measurement system was developed using a Fourier Transform Infrared (FTIR) spectrometer. This experimental set-up was successfully demonstrated in resolving THz emission by using step-scan and lock-in techniques, and a fast Ge:Ga photon detector. Spontaneous intersubband THz emission was observed with linewidth narrower than 0.65 THz, and center frequency at the designed value of 3.8 THz. Different triple-quantum-well structures were designed, grown, and tested. The measured emission power levels were one order of magnitude lower than calculated values, and possible extra cavity loss mechanisms were discussed. To verify the triple-quantum-well structure design, a mid-infrared absorption measurement was performed on a sample grown on semi-insulating substrate. Information such as subband energy separations, dipole moments, and linewidth broadening, was extracted from the absorption spectrum and gave a good confirmation on numerical simulations and MBE growth quality of the MQW structures.
by Bin Xu.
Ph.D.

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19

Koletsios, Evangelos. "GaAs/InAs multi quantum well solar cell." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/27856.

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In this thesis, Silvaco software is used to form a precise, well-controlled reliable, and inexpensive solar-cell structure using quantum wells. Successful results will allow the exploitation of most of the advantages of quantum-well systems. This challenging research represents the first time that Silvaco simulation software has been used in the design of such a solar cell. This research field is promising because of the potential to increase the attainable energy efficiency of solar photon conversion, due to tunable bandgaps, which can absorb most of the solar spectrum, which conventional single-layer crystalline solar cells cannot do. The ultimate goal is the assembly of a quantum-well layer. A theoretical infinite-layer cell can reach an efficiency of 86% (constrained by thermodynamical limits). Quantum wells can reach 65%+ when a multilayer cell has reached 49%, and it is very expensive to build.

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20

Murphy, Francis John. "Infrared spectroscopy of multi-quantum well microcavities." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24442.

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Two projects are presented in this thesis. The first project is an investigation into linewidth-narrowing phenomena of intersubband cavity polaritons (ICPs) in a microcavity/multi-quantum well sample through angle-resolved laser spectroscopy. Strong coupling of the vacuum field of the microcavity, and the intersubband transition (ISBT) of the multi-quantum well led to vacuum Rabi splitting of 12.4 meV of the ICP modes at room temperature in the absorbance spectra. The linewidths of the ICPs were found to be substantially narrowed (4.2 meV, at room temperature) at the anticrossing point, narrower than the bare ISBT and empty microcavity linewidths at room temperature (6.2 and 6 meV, respectively, at room temperature), and narrower than existing theory predicted. The same effect was observed at cryogenic temperatures. Narrowing was explained by the light effective mass of the ICP, rendering the ICP unaffected by interface roughness scattering of the multi-quantum well. The measurement of the narrow linewidths was made possible by the superior angular resolution of laser spectroscopy compared to previously-used thermal light sources. The second project consisted of the development of a Q switched Er 3+ ,Cr 3+ :YSGG laser, of 3 μm wavelength, with 76 mJ fundamental mode pulses in free-running mode. Q switching of the laser was investigated in order to produce short (<400 ns) laser pulses, using two 'slow' Q switch methods. The first, a rotating mirror Q switch, was found to produce pulses of ~10 mJ, with an optimum mirror rotation rate of 300 rotations per second. The second Q switch method, a 'polygon chopper Q switch' produced single pulses of energy ~4 mJ, using a rotating polygon as an optical chopper. From this Q switch, it was deduced that the longest Q switching time possible for Er 3+ ,Cr 3+ :YSGG, with any method of Q switching, was ~30 μs for single pulse operation, and ~80 μs for multiple pulses.

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21

Böhringer, Klaus. "Microscopic spatio-temporal dynamics of semiconductor quantum well lasers and amplifiers." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-33475.

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22

Derry, Pamela L. Yariv Amnon Yariv Amnon. "Properties of buried heterostructure single quantum well (Al, Ga)As lasers /." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechETD:etd-02052007-093221.

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23

Gonul, Besire. "A theoretical study of the threshold current of quantum well lasers." Thesis, University of Surrey, 1995. http://epubs.surrey.ac.uk/844377/.

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The work described in this thesis is a theoretical investigation of the effects of band structure, strain, pressure, and growth orientation on the performance of semiconductor quantum well lasers. The effect of degenerate light- and heavy-hole bands on the carrier and current density and the differential gain are studied and compared with the non-degenerate case in semiconductor quantum well (QW) lasers. It is demonstrated that the presence of two degenerate bands at the valence band maximum will always lead to an increased threshold radiative current density compared to the case where only one band is significantly populated. When the two valence bands are separated by an energy E5, the current density decreases rapidly with increasing E5, with greater reductions being achieved for a given tensile than compressive strain. The effect of the second subband becomes less important with increasing E5, and the radiative current density reverts to that of the one valence band case, demonstrating the importance of maximising the subband energy separation to optimise laser characteristics. We investigate different formulations of the envelope function method and show that the accuracy of the calculated zone-centre confinement energies can be simply predicted by plotting the equivalent bulk band structure using the various formulations. We show how coupling to the conduction and spin-split-off bands can decrease the light-hole zone-centre energies and lead to significant differences in the calculated subband dispersion, with the effects being most pronounced for systems having a narrow band gap and small spin-orbit splitting energy. Since the loss mechanisms in a semiconductor laser are often strongly wavelength dependent and hydrostatic pressure can vary the band gap, the pressure dependence of the threshold current can then provide a clear picture of the dominant loss mechanisms in a given laser structure. The pressure dependence of the optical confinement factor, band structure, transparency and threshold carrier density, and the combined effect of these on both radiative- and non-radiative current contributions have been evaluated for lasers operating at a range of wavelengths. We investigate in particular the predicted pressure dependence of several Auger processes in long wavelength (1.5mum) lasers. It is found that the rate of decrease of phonon-assisted Auger recombination with pressure is close to that observed experimentally, implying that phonon-assisted Auger is the dominant loss mechanism. It is shown that although the transparency carrier density increases with pressure in all laser structures, the threshold carrier density, nth, can decrease in long wavelength single quantum well (SQW) lasers due to the pressure dependent parameters. The decrease of nth in the long wavelength SQW case results in a quicker decrease in the threshold current of a SQW laser compared to that of a multiple quantum well (MQW) laser, in agreement with experimental measurements. The optical properties of quantum well structures can also change with crystal orientation, and, therefore, the substrate orientation is an additional parameter which can be used in engineering the band structure. The effects of orientation on critical thickness and material parameters are reviewed for (001) and (111) oriented strained InGaAs QWs grown on GaAs substrates and their consequences for laser emission wavelength are investigated. Calculations are presented which show that a significant fraction of the piezoelectric field remains unscreened at laser threshold in (111) lasers, which, together with decreased HH1-HH2 separation, adversely affect the laser threshold characteristics in comparison to (001) oriented strained lasers.

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24

Malins, David Brendan. "Ultrafast dynamics in InAs quantum dot and GaInNAs quantum well semiconductor heterostructures /." St Andrews, 2007. http://hdl.handle.net/10023/404.

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25

Yee, Hoshin Hocking. "Semiconductor quantum-well extended cavity lasers and deep-surface gratings for distributed surface Bragg reflector lasers." Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309492.

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26

O'Hagan, Seamus. "Multi-mode absorption spectroscopy for multi-species and multi-parameter sensing." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:6f422683-7c50-47dd-8824-56b4b4ea941d.

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The extension of Multi-mode Absorption Spectroscopy (MUMAS) to the infra-red spectral region for multi-species gas sensing is reported. A computationally efficient, theoretical model for analysis of MUMAS spectra is presented that avoids approximations used in previous work and treats arbitrary and time-dependent spectral intensity envelopes, thus facilitating the use of commercially available Interband Cascade Lasers (ICLs) and Quantum Cascade Lasers (QCLs). The first use of an ICL for MUMAS is reported using a multi-mode device operating at 3.7 μm to detect CH₄ transitions over a range of 30 nm. Mode-linewidths are measured using the pressure-dependent widths of an isolated absorption feature in HCl. Multi- species sensing is demonstrated by measurement of partial pressures of CH₄, C₂H₂ and H₂CO in a low-pressure mixture with uncertainties of around 10%. Detection of CH₄ in N₂ at 1 bar is demonstrated using a shorter-cavity ICL to resolve spectral features in pressure-broadened and congested spectra. The first use of a QCL for MUMAS is reported using a commercially available device operating at 5.3 μm to detect multiple absorption transitions of NO at a partial pressure of 2.79 μbar in N₂ buffer gas. The revised model is shown to enable good fits to MUMAS data by accounting for the time-variation of the spectral intensity profile during frequency scanning. Individual mode-linewidths are derived from fits to pressure- dependent MUMAS spectra and features from background interferences due to H₂O in laboratory air are distinguished from those of the target species, NO. Data obtained at scan rates up to 10 kHz demonstrate the potential for achieving short measurement times. The development of a balanced ratiometric detection scheme for MUMAS with commercially available multi-mode lasers operating at 1.5 μm is reported for simultaneous detection of CO and CO₂ showing improved SNR performance over previous direct transmission methods and suitability for a compact field-employable instrument. In addition, MUMAS spectra of CO₂ are used to derive gas temperatures with an uncertainty of 3.2% in the range 300 - 700 K.

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27

Tsou, Benjamin Pen-Cheng. "Equivalent-circuit modeling of quantum-well lasers and fibre-optic communications channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/NQ48730.pdf.

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28

Eddie, Iain Mackenzie. "Carrier confinement in vertical-cavity surface-emitting lasers by quantum well intermixing." Thesis, University of Glasgow, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433190.

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29

JovanovicÌ, Vladimir. "Theory and design of GaAs and GaN-based quantum cascade lasers and quantum well infrared photodetectors." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418242.

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30

Panapakkam, Venkatesan Vivek. "Optical frequency comb generation using InP based quantum-dash/ quantum-well single section mode-locked lasers." Thesis, Evry, Institut national des télécommunications, 2016. http://www.theses.fr/2016TELE0024/document.

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Les interconnections optiques dans les fermes de données (data centers) nécessitent la mise au point de nouvelles approches technologiques pour répondre aux besoins grandissants en composants d’interface respectant des cahiers de charge drastiques en termes de débit, coût, encombrement et dissipation d’énergie. Les peignes de fréquences optiques sont particulièrement adaptés comme nouvelles sources optiques, à mêmes de générer un grand nombre de porteuses optiques cohérentes. Leur utilisation dans des systèmes de transmission en multiplexage de longueurs d’onde (WDM) et exploitant de nouveaux formats de modulation, peut aboutir à des capacités jamais atteintes auparavant. Ce travail de thèse s’inscrit dans le cadre du projet européen BIG PIPES (Broadband Integrated and Green Photonic Interconnects for High-Performance Computing and Enterprise Systems) et a pour but l’étude de peignes de fréquences générés à l’aide de lasers à verrouillage de modes, à section unique, à base de bâtonnets quantiques InAs/InP et puits quantiques InGaAsP/InP. Nous avons entrepris l’étude de nouvelles couches actives et conceptions de cavités lasers en vue de répondre au cahier des charges du projet européen. Une étude systématique du bruit d’amplitude et de phase de ces sources a en particulier été menée à l’aide de nouvelles techniques de mesure afin d’évaluer leur compatibilité dans des systèmes de transmission à très haut débit. Ces peignes de fréquences optiques ont été utilisées avec succès dans des expériences de transmission sur fibre optique avec des débits records dépassant le Tbit/s par puce et une dissipation raisonnable d’énergie par bit, montrant leur fort potentiel pour les applications d’interconnections optiques dans les fermes de données
The increasing demand for high capacity, low cost, high compact and energy efficient optical transceivers for data center interconnects requires new technological solutions. In terms of transmitters, optical frequency combs generating a large number of phase coherent optical carriers are attractive solutions for next generation datacenter interconnects, and along with wavelength division multiplexing and advanced modulation formats can demonstrate unprecedented transmission capacities. In the framework of European project BIG PIPES (Broadband Integrated and Green Photonic Interconnects for High-Performance Computing and Enterprise Systems), this thesis investigates the generation of optical frequency combs using single-section mode-locked lasers based on InAs/InP Quantum-Dash and InGaAsP/InP Quantum-Well semiconductor nanostructures. These novel light sources, based on new active layer structures and cavity designs are extensively analyzed to meet the requirements of the project. Comprehensive investigation of amplitude and phase noise of these optical frequency comb sources is performed with advanced measurement techniques, to evaluate the feasibility of their use in high data rate transmission systems. Record Multi-Terabit per second per chip capacities and reasonably low energy per bit consumption are readily demonstrated, making them well suited for next generation datacenter interconnects

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31

Tan, Hua. "Chirp and Linewidth Characteristics in Semiconductor Quantum Dot Lasers." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258477064.

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32

Mellish, Robert. "Ultrafast and all-solid-state Cr:LiSAF lasers." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243457.

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33

Chan, Chu-yuen. "Electronic and optical properties of interdiffused III-V semiconductor quantum well laser /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1966722X.

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34

Bushnell, David Benjamin Bovett. "Optimisation of strain-compensated multi-quantum well solar cells." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397649.

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35

Chan, Chu-yuen, and 陳柱元. "Electronic and optical properties of interdiffused III-V semiconductorquantum well laser." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31236534.

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36

Bauer, Sven [Verfasser]. "High-Speed 1.55 µm Quantum Dot Lasers with Electronically Coupled Quantum Well - Dot Active Regions / Sven Bauer." Kassel : Universitätsbibliothek Kassel, 2019. http://d-nb.info/1201500753/34.

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37

Yong, Jennifer Chai Lin. "Investigation of quantum well material systems for 1300nm wavelength high-speed uncooled lasers." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399933.

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38

Wang, Tsuei-Lian. "High-Power Optically Pumped Semiconductor Lasers for Near Infrared Wavelengths." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242398.

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Optically pumped semiconductor lasers (OPSLs) combine features including an engineerable emission wavelength, good beam quality, and scalable output power and are desirable for a wide variety of applications. Power scaling of OPSLs requires a combination of accurate epitaxial quantum design, accurate wafer growth and good thermal management. Here a fabrication process for OPSL devices was developed to ensure efficient OPSL device cooling and minimum surface scattering. A systematic thermal analysis was performed to optimize thermal management. Strategies for optimizing power extraction were developed; including increasing the gain/micro-cavity detuning that increases the threshold but also increases the slope efficiency and the roll-over temperature, recycling the excess pump via reflection from a metalized reflector at the back of a transparent DBR, anti-reflection coating at the pump wavelength while preserving the signal micro-cavity resonance. With optimized thermal management and the strategy of using large gain/micro-cavity detuning structure, a CW output power of 103 W from a single OPSL device was achieved. 42% optical-to-optical efficiency from the net pump power was obtained from the OPSL device with the double pass pump design and 39% optical-to-optical efficiency with respect to the total pump power was obtained with the new pump anti-reflection coating. For the fundamental mode operation, over 27 W of CW output power was achieved. To our knowledge, this is the highest 1 µm TEM₀₀ mode power reported to date for an OPSL. Finally, strategies for generating high peak power are also discussed. A maximum peak power of over 270 W was achieved using 750 ns pump pulses.

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39

Malins, David B. "Ultrafast dynamics in InAs quantum dot and GaInNAs quantum well semiconductor heterostructures." Thesis, University of St Andrews, 2008. http://hdl.handle.net/10023/404.

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The quantum confined Stark effect (QCSE) and ultrafast absorption dynamics near the bandedge have been investigated in p-i-n waveguides comprising quantum confined heterostructures grown on GaAs substrates, for emission at 1.3um. The materials are; isolated InAs/InGaAs dot-in-a-well (DWELL) quantum dots (QD), bilayer InAs quantum dots and GaInNAs multiple quantum wells (MQW). The focus was to investigate these dynamics in a planar waveguide geometry, for the purpose of large scale integration in optical systems. Initial measurements of the QCSE using photocurrent measurements showed a small shift for isolated QDs whilst a significant shift of 40nm (at 1340nm) was demonstrated for bilayer dots, comparable to that of GaInNAs MWQ (30nm at 1300nm). These are comparable to InP based quaternary multiple quantum wells used in modulator devices. With the use of a broadband continuum source the isolated quantum dots exhibit both a small QCSE (15nm at 1280nm) and minimal broadening which is desirable for saturable absorbers used in monolithic modelocked semiconductor lasers (MMSL). A robust experimental set-up was developed for characterising waveguide modulators whilst the electroabsorption and electro-refraction was calculated (dn=1.5x10â »Â³) using the Kramers-Kronig dispersion relation. Pump probe measurements were performed at room temperature using 250fs pulses from an optical parametric oscillator (OPO) on the three waveguide samples. For the isolated QDs ultrafast absorption recovery was recorded from 62ps (0V) to 700fs (-10V and the shortest times shown to be due to tunneling. Additionally we have shown good agreement of the temperature dependence of these dots and the pulse width durations from a modelocked semiconductor laser using the same material. Bilayer QDs are shown to exhibit ultrafast absorption recovery from 119ps (0V) to 5ps (-10V) offering potential for applications as modelocking elements. The GaInNAs multiple quantum wells show absorption recovery of 55ps (0V), however under applied reverse bias they exhibit long lived field screening transients. These results are explained qualitatively by the spatial separation of electrons and holes at heterobarrier interfaces.

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40

Huang, Rong. "Study of temperature characteristics of 1.3[mu]m strain-layer multiple quantum well lasers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ30147.pdf.

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41

Sadeghi, Seyed Mostafa. "Nonlinear optical properties of quantum well structures in the presence of intense infrared lasers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0020/NQ46411.pdf.

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42

Page, Hideaki. "The intrinsic carrier dynamics of InGaAs/AIGaAs single quantum well, strained-layer, semiconductor lasers." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/771942/.

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43

Moreira, Manuel Viotr A. "Fabrication and characterisation of surface grating DFB lasers using AlGaAs/GaAs quantum well material." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361730.

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44

McDougall, Stewart Duncan. "Monolithic colliding pulse mode-locking of AIGaAs/GaAs and InGaAs/InaAsP quantum well lasers." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360181.

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45

Jones, Dewi Robert. "Theoretical investigation of self-pulsating laser diodes for optical storage applications." Thesis, Bangor University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341178.

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46

Hsu, Hong-Ting, and 許鴻挺. "Asymmetric Multi-Quantum-Well Spot-Size Converter Lasers." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/75198500035814019835.

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碩士
國立中山大學
光電工程研究所
89
Abstract The purpose of this thesis is to fabricate l = 1.55mm ridge waveguide spot size converter lasers for high laser-to-fiber coupling. The laser structure design includes the lateral and vertical directions. In the vertical aspect, we use six asymmetric InGaAsP/InP quantum wells of 50, 50, 100, 100, 150, 150Å. The asymmetric multi-quantum-well structure is designed to gather the optical field in the 150Å-wide quantum wells. Besides, we add a passive waveguide near the 150Å-wide quantum wells to expand optical field profile. In the lateral aspect, we use tapered ridge waveguides which have two different fashions: one is tapered down from 2.5mm to 1mm, and the other is tapered up from 2.5mm to 4mm. The results show that the tapered-up ridge waveguide laser has a CW operation with Ith = 34mA and diverge angles of 14°×36° (q//×q^) at room temperature. The tapered-down ridge waveguide laser exhibits only a pulsed operation at room temperature. At lower temperature T = 13°C, the tapered-down laser has a CW operation of Ith = 36mA and diverge angles of 14°×36°(q//×q^). From I-V and C-V measurements, we attribute the heating problem to the large series resistance caused by the incorrect n-type doping profile in the epitaxy process.

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47

Wu, June-Han, and 吳俊翰. "Fabrications of Multi-quantum-well Spot-size Converter Lasers." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/21940782200311265627.

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碩士
國立中山大學
光電工程研究所
87
We present the fabrications of 1.55 mm InGaAsP/InP multiple-quantum-well spot-size converter lasers. In the lateral conversion, we use photolithography to make tapered ridge waveguides. In the vertical conversion, we design a regrowth-less epi-structures by adding a pair of passive waveguides, namely, guard waveguides (GWs), in two sides of the step-index active waveguide region to increase optical-field profile. The 2.5-to-1.0 mm tapered ridge waveguide laser of GW structure shows a threshold current (Ith) ~ 23mA and a characteristic temperature (T0) ~ 50K. Moreover, the 2.5-to-4.0 mm tapered laser exhibits Ith ~ 30mA and T0 ~ 60K and a far-field divergence at 20°x 28°(lateral x vertical), which is consistent with the numerical simulations and is of great improvement to the 30°x 40°output of usual Fabry-Perot lasers.

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48

chau, K. G., and 趙昆基. "The study of 1.3 um InAlGaAs multi-quantum well lasers." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/44284023347869562845.

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碩士
國立中央大學
電機工程學系
85
1.3 um InAlGaAs/InP GRINSCH multi-quantum well lasers were grown by molecularbeam epitaxy (MBE).We obtained characteristic temperature as high as 80K for anas-cleaved laser.We have also fabricated InAlGaAs/InP multi-quantum well laserswith a multi- quantum barrier structure at the optical confinment layer . It is found that temperature-threshold characteristics are improved by introducing the MQB.

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49

吳欣彥. "The Fabrication of 1.5μm AlGaInAs Strained Multi-Quantum Well Distributed Feedback Lasers." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/54497634363497492242.

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碩士
國立交通大學
光電工程研究所
86
we present the fabrication results of the 1.5um complex-coupled distributed feedback lasers (DFB lasers ) with a InGaAs loss grating and strained A1GaInAs multi-quantum well (MQW) active region. The device with coupling coefficient of 30 cm-1 has a CW threshold current of 19mA and a output power of 29mW. Stable single mode emission was demonstrated with a side mode suppression ratio of up to 44dB at 5mW output power. It has been found that the presence of loss-coupling strength can eliminate the mode degenercy effectively.

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50

Yeh, Feng Chun, and 葉逢春. "Near-Field Optical Characterization of Multi-Quantum Well Laser Diodes." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/27291461086388596206.

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碩士
淡江大學
物理學系
85
Optical characterization of the active region of a semiconductor laseris an important subject. It helps us optimize the output performance of the semiconductor laser. Being restricted to the diffraction limit, the spatial resolution is about one half wavelength by using conventionaloptical method. Thus scientists are eager for new optical techniqueswith higher resolution.This was realized by the advance of near-fieldoptical technique. Scanning near-field optical microscope (SNOM) is a new technique,which uses the scanning probe microscope in combination with a taperedfiber probe. The side wall of the taper is coated with a metallic thin filmsuch that an optical aperture is formed on the tip. The tip-sample distance is kept at≒10nm by using the shear force mechanism. In the same time, the taper can emit or collect the near-field signal. With this method, we can simultaneously obtain the topographic and near- field optical image.We use near-field microscope modified from atomic force microscope to observe the comparison between topography and near-field optical image. We also acquire optical image at various drive currents and tip-sample distances. Again we analyze the spectra by channeling the optical signal to onochromator. Coupling modulation laser to probe we can obtain near-field optical photoconductivity. These high resolution information offer us the laser structure, qualitative and output characteristics. This has great advantage for studying semiconductor lasers.

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