Dissertations / Theses on the topic 'Two infrared light sources'

This thesis describes how for the first time, unidirectional operation and coupled ring tuning were realised on a quantum cascade laser material; specifically on a new strain compensated In0.7Ga0.3As/AlAs0.6Sb0.4 grown on InP substrate and operates in pulsed mode in the 3-4 micron hydrocarbon absorption region. Unidirectional ring lasers have the advantages that, in the favoured emission direction, they can have up to double the quantum efficiency of bidirectional lasers and do not suffer from spatial hole burning. In this work, this operation was realised by incorporating an "S"-crossover waveguide into the ring cavity in a manner that it introduces non reciprocal loss and gain in the counter-clockwise (CCW) and clockwise (CW) directions respectively. The measured result showed higher quantum efficiency in the CW. In fact at 1.5 times the threshold current, 90 % of the light was emitted in the favoured CW. On the other hand, the coupled ring quantum cascade laser showed nearly single mode operation, with side mode suppression ratio ~22 dB. Continuous wavelength tuning of about 13 nm was observed from one of these devices, at a tuning rate of approximately 0.4 nm/mA.

Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 47-52).<br>The efficient extraction of light from silicon is one of the longstanding challenges of modem engineering and physics. The difficulty mainly arises from silicon's indirect bandgap and the short lifetime of non-radiative processes such as Auger recombination. Nonetheless, the realization of an energy efficient silicon-based photon source could find broad applicability in areas such as ultra-large scale integration (ULSI), optoelectronic displays and lighting. Every practical solution proposed thus far to this fundamental, yet technologically critical problem, relies on the physical patterning or chemical modification of silicon substrates, most of these transformations requiring high annealing temperatures or fabrication steps that are not compatible with conventional ULSI processes. In this thesis, we experimentally demonstrate the generation of tunable radiation in the near-infrared (800 to 1600 nm) from a simple periodic silicon grating. The light emission is generated by spontaneous emission from these gratings interacting with low-energy free electrons (as low as 2 keV) and is recorded in the silicon transparency window. We develop time-domain numerics that confirms our experimental results and our evaluation of the output radiation power. In addition, we theoretically investigate the feasibility of an allsilicon compact tunable radiation source at telecommunication wavelengths comprised of a silicon Field Emitter Array (FEA) integrated with a silicon periodic structure. Our results pave the way towards the realization of a CMOS-compatible electrically-pumped silicon light source.<br>by Charles Roques-Carmes.<br>S.M.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>PROGRAMA DE EXCELENCIA ACADEMICA<br>Detectores de infravermelho possuem larga gama de aplicações em diversos setores, desde militares (visão noturna, mísseis) até civis (aparelhos eletrônicos). Nesta dissertação estivemos interessados nas absorções intrabanda de heteroestruturas multiepitaxiais com intuito de absorver infravermelho em 4,1 micra onde se localiza a primeira janela de transmissão atmosférica. Baseamos nossas heteroestruturas de poços quânticos em semicondutores da família III-V. Discorremos quanto a produção do dispositivo de forma detalhada, juntamente com todos os processos de calibração de cada etapa. O crescimento se dá pela técnica de MOVPE que possui alta precisão em termos da espessura e composição da camada depositada. Em seguida discutimos sobre o processamento da amostra crescida para expor os contatos elétricos. E finalizamos descrevendo o processo de integração do dispositivo sobre um suporte para leitura do sinal. Finalizada a etapa de produção, fizemos um estudo quanto às características da amostra tanto qualitativamente quanto quantitativamente. Este estudo objetivou a obtenção de duas informações: comparação direta entre as geometrias de acoplamento luminoso; e medição da eficiência dos detectores produzidos. Ao fim do trabalho obtivemos um fotodetector produzido desde seu crescimento até sua montagem final. Assim como os resultados da eficiência dos mesmos que já indicaram melhorias possíveis para trabalhos futuros. Visando a formação de um mercado de produção em larga escala de fotodetectores, este trabalho identificou áreas com carência de técnicas disponíveis e que necessitam de investimento.<br>Infrared detectors have a wide range of applications in various industries, from military (night vision, missile) to civil (electronics). In this dissertation we were interested in the intraband absorption of multiepitaxial heterostructures with aim at absorption of 4.1 microns infrared where there s located the first atmospheric transmission window. We based our quantum well heterostructures in semiconductor from the III-V family. We discourse about the production of the device in detail, along with all the calibration procedures for each step. The growth is done by MOVPE technique that has high accuracy in terms of thickness and composition of the deposited layer. We then discuss about the processing of the grown sample to expose the electrical contacts. And finally we describe the process of integration of the device over a base for reading the signal. Completed the production stage, we studied the characteristics of the sample both qualitatively and quantitatively. This study aimed to obtain two pieces of information: a direct comparison between the methods for light coupling, and measuring the efficiency of the detectors produced. At the end of the work we obtained a photodetector produced from its growth till its final assembly. Also we obtained the results of the efficiency of the sample that already indicated possible improvements for future works. If the aim is at the formation of a large-scale production of photodetectors, this study identified areas with a shortage of available techniques and in need of investment.

Zur Untersuchung nichtlinearer Reaktionen von kondensierten Materie-Systemen wird die multidimensionale Terahertz-Spektroskopie genutzt. Ein mehrere Oktaven umfassende THz-Quelle, die auf der Frequenzmischung in organischen Kristallen basiert, wird entwickelt und zur Erforschung der Librationsbande von Wasser-Nanotröpfchen in DOPC-Micellen verwendet. Die nichtresonante THz-Strahlung wird genutzt, um die Emission im mittleren Infrarotbereich eines Intersubband-Übergangs von GaAs-Quantentöpfen kohärent zu steuern. Schließlich wird die 2D-THz-Spektroskopie verwendet, um die nichtlineare Antwort einer "soft-mode" in einem Aspirin-Molekül-Kristall zu studieren.<br>Multidimensional Terahertz spectroscopy is used to investigate the nonlinear response of condensed matter systems. A multioctave-spanning THz source based on frequency mixing in organic crystals is developed and used to study the libration band of water nanodroplets confined in DOPC micelles. Nonresonant THz radiation is used to coherently control the mid-infrared emission of an intersubband transition of GaAs quantum wells. Finally, 2D THz spectroscopy is used to study the nonlinear response of a soft mode in an aspirin molecular crystal.

In this work, novel quantum well structures were grown by molecular beam epitaxy (MBE). Samples have been designed in order to allow access to light sources from InP based type I interband devices, for the technologically important mid-infrared (Mid-IR) (2-5 um) spectral range. Investigations of dilute nitride InGaAsN and InAsN were performed with the intent to highlight the potential availability of type-I MQW structures grown onto InP substrates emitting Mid-IR radiation. This thesis describes the successful attempt to overcome restrictions imposed by lattice mismatch and resultant critical thickness limitations as described by past experiments with these materials, where conventional III-V alloy materials are restricted to 2.3pm and dilute nitride materials have been previously reported as emitting up to 2.6pm within this strained MQW regime.

High-power, continuous-wave (cw), mid-infrared (mid-IR) laser sources are of interest for variety of applications such as trace gas detection and remote sensing, which require broad spectral coverage to address the most prominent absorption features of a wide range of molecular species particularly in the mid-IR fingerprint region. On the other hand, surgical applications require high energy sources with unique pulse structure at specific wavelength in the mid-IR ranging from 6-6.5 m. Optical parametric oscillators (OPOs) offer potential sources for all the above applications. The output wavelengths of a singly-resonant oscillator (SRO) can be coarsely tuned over wide ranges through the adjustment of the nonlinear crystal temperature, phase-matching angle or, in the case of quasi-phase-matched (QPM) the first time. The high-energy CSP OPO marked the first demonstration of a compact, high-repetition-rate OPO synchronously pumped by a master oscillator power amplifier system at 1064 nm, generating an milli-joule pulses in the 6-6.5 m spectral range, which is technologically important for surgical applications. Additionally, we also demonstrated a fiber-based-green source at 532 nm, based on single-pass second harmonic generation (SHG) in MgO:sPPLT, as an alternative pump source for Ti:sapphire laser, pointing towards the future, compact fiber-laser pumped Ti:sapphire lasers. Further efforts to improve the SHG efficiency led to the development of a novel multi-crystal scheme, enabling single-pass SHG efficiency as high as 56%. This generic technique is simple and can be implemented at any wavelength. materials, the QPM grating period. The combination of SRO with a tunable pump laser allows the development of uniquely flexible and rapidly tunable class of mid-IR sources. In this thesis we have demonstrated several mid-IR OPOs in the cw as well as ultrafast picosecond regime pumped by fiber-lasers making them compact and robust. In the cw regime, we developed a high-power, Yb-fiber-laser pumped mid-IR OPO based on MgO:PPLN spanning 1506-1945 nm in the near-IR and 2304-3615 nm wavelength range in the mid-IR, efficiently addressing the thermal effects by implementing the optimum signal output coupling. Novel materials such a MgO:sPPLT, with better optical and thermal properties for cw mid-IR generation are explored. High-power broadband, cw mid-IR generation is also demonstrated by using the extended phase-matching properties of MgO:PPLN. Further, we also demonstrated a simple, inexpensive and novel interferometric technique for absolute optimization of output power from a ring optical oscillator. We deployed a picosecond Yb-fiber-laser pumped mid-IR OPO based on MgO:PPLN in ring cavity configuration to demonstrate this proof-of-principle experiment for<br>Fuentes coherentes de luz continua y de alta potencia en el infrarrojo-medio (mid-IR) son de gran interés por su aplicación en la detección de gases, detección remota y la observación de imágenes. Estas aplicaciones requieren un ancho de banda amplio para evidenciar las características que ofrece la absorción de una gran variedad de especies moleculares, particularmente en la región “finger print” del mid-IR. Por otra parte, fuentes altamente energéticas con pulsos que posean estructuras peculiares en rangos específicos de longitud de onda en el mid-IR, entre 6-6.5 m. , prometen características únicas para nuevas aplicaciones en cirugía. Osciladores ópticos paramétricos (OPOs) constituyen fuentes de luz versátiles y apropiadas para todas las aplicaciones mencionadas anteriormente. La longitud de En el régimen ultrarápido, hemos demostrado una nueva técnica de interferometría para la optimización absoluta de la potencia de salida de un oscilador óptico con una cavidad de anillo. Como demostración de principio, implementamos, por primera vez, un OPO de picosegundos en el mid-IR basado en MgO:PPLN con una cavidad de anillo bombeado por un láser de fibra de Yb. Además, hemos desarrollado un nuevo OPO de alta energía en el mid-IR basado en el material nolineal CSP. Esto representa la primera demostración de un OPO compacto de alta repetición sincrónicamente bombeado por un láser de estado sólido a 1064 nm generando pulsos de milijulios en el rango espectral 6-6.5 m. Esta radiación es importante para aplicaciones en cirugía. Adicionalmente, hemos demostrado una fuente verde, 532 nm, basada en láseres de fibra. Esta radiación se obtiene por medio de la generación de segundo harmónico (SHG) en un paso individual en MgO:sPPLT. Esto representa una nueva alternativa de bombeo para los láseres de Ti:sapphire que los harán compactos en el futuro. Los esfuerzos para mejorar la eficiencia de segundo harmónico resultaron en el desarrollo de un novedoso esquema que utiliza múltiples cristales y permite eficiencias de SHG de paso individual del 56%. Este esquema es general y simple y puede ser implementado para cualquier longitud de onda. onda de un OPO puede ser sintonizada en regiones amplias del espectro cambiando la temperatura del cristal no-lineal, el ángulo de ajuste de fase o, al considerar materiales cuasi ajuste de fase (QPM), cambiando el periodo de red. En esta tesis, hemos demostrado una gran variedad de OPOs en el mid-IR en régimen continuo y de pulsos de picosegundo. Estos OPOs han sido bombeados por láseres de fibra permitiendo un diseño compacto y resistente. En el régimen de emisión continua, hemos implementado un OPO de alta potencia basado en MgO:PPLN bombeado por un láser de fibra. Este OPO es sintonízable en el rango 1506-1945 nm correspondiente al infrarrojo-cercano y en el rango 2304-3615 nm correspondiente al mid-IR. Esta capacidad de sintonización se logra al sobrepasar eficientemente los efectos térmicos optimizando el acoplamiento de salida. Materiales nuevos como el MgO:sPPLT, con propiedades ópticas y térmicas mejoradas para la generación de radiación continua en el mid-IR han sido estudiados. Utilizando las propiedades ajuste de la fase extendió del MgO:sPPLT, fuentes continuas de alta potencia con un gran ancho de banda en el infrarrojo-medio también han sido implementadas.

Poor water quality is a global health concern affecting one billion people around the world. It is important to monitor water sources in order to maintain the quality of our drinking water and to avoid disease outbreaks. Targeting Escherichia coli as a faecal indicator is a widely used procedure, but the current methods are time consuming and not adequate to prevent spreading of faecal influence.   This Master thesis demonstrates the development of a near infrared fluorescence flow cytometer sensor system targeting Escherichia coli, using fluorescently labeled chicken IgY antibodies. The near infrared light was chosen to avoid fluorescence from blue-green algae that are present in the water source.   The hardware was developed with a 785  nm laser line to detect Alexa Fluor 790 labeled antibodies, using a photomultiplier tube or two different CMOS cameras. The antibodies were labeled using a commercial labeling kit, and evaluated using antibody binding assays and the developed hardware.   The IgY antibodies were successfully labeled with Alexa Fluor 790 and the function was maintained after the labeling process. The result demonstrates the principles of the sensor system and how it solved to the problem with fluorescence from blue-green algae. An aperture was used to overcome the suboptimal laser and filter setup, and to increase the sensitivity of the system. However, only a small fraction of the cells could be detected, due to challenges with the focal depth and loss of sensitivity in the photomultiplier tube at near infrared wavelengths. Further development is required to create a working product.

Telemetry system, Optimisation, Sensoric networks, Smart Grid, Internet of Things, Sensors, Information security, Cryptography, Cryptography algorithms, Cryptosystem, Confidentiality, Integrity, Authentication, Data freshness, Non-Repudiation.

碩士<br>國立臺灣大學<br>材料科學與工程學研究所<br>105<br>In this thesis, we study the silicon (Si) based devices working in the infrared (IR) regime, including broadband IR photodetector and IR light source (emitter) with high emissivity. In the first part of the thesis, we focus on overcoming the limitation of Si band gap for broadband IR photodetection. We useed an ion implantation process on structured Si to fabricate a heavily doped Si layer. The mechanism of free carrier absorption in heavily doped Si increases the absorption of Si in the IR regime. In this thesis, we investigate the broadband Si based IR detector by integrating metal-insulator-semiconductor (MIS) structure with a heavily doped Si layer on a structured Si substrate. Different from the previous studies of Si-based IR photodetectors, which used the mechanism of Shottcky junction, we apply the band valley of ohmic junction to accumulate free carriers near the interface of Si and insulator (oxide). As the ohmic junction reaching the thermal equilibrium condition, the band valley would be formed by the band bending effect of the junction. By illuminating with IR light, the carrier would tunnel through the oxide layer to perform photoresponse. Moreover, the IR light illuminated into the backside of Si and can pass through lightly-doped Si substrate. Because the refractive index of Si is larger than that of air, the light passing through the lightly doped region can enhance the electromagnetic field of light, further increasing the absorption of the device. The measured absorption of the device can be up to 0.7. Furthermore, the device can operate at the wavelengths of 2μm, 3.25μm, 6μm, and 10μm IR bands and the photo-voltage-response is 10.09 mV/W, 10.81 mV/W, 16.88mV/W, 19.00 mV/W, respectively. The devices can operate at room temperature and without any bias voltage , achieving the goal of developing a Si-based infrared photodetector with low power consumption and broadband working capability. In the second part of the thesis, we focus on extending and increasing the emissivity of tungsten from near IR (NIR) to mid IR (MIR) spectral regimes in order to develop a broadband and low cost IR emitter. Tungsten is a common material used in visible light illumination for a long time. The drawback is that the emissivity of tungsten is very low in the broad IR regime. We develop the periodical deep trench and cover it with only 160nm of tungsten film. By using the light emitting from backside of Si, we are able to significantly enhance the emissivity of tungsten in the broadband regime from 1 to 25μm. In the simulation, we use the structure of periodical deep trenches to enhance the average absorption of tungsten to 0.9 in the broad infrared band. In the experiment, we use black tape and thermal imager to calibrate the emissivity of our device, and the average emissivity is about 0.7 at 8~13μm. The experimental result demonstrate that the radiation energy of the device largely enhanced by the structure. By coating the antireflective layer on the backside of Si, the absorption/emissivity of the device further increased to close to 0.9. In the third part of the thesis, the thermal radiation properties of heavily doped on structured Si wafer were investigated. We developed an all-Si based device that can be used as an IR emitter by combining the the property of high absorption of heavily doped Si and the optimal trenched structures. In the optical simulation, we found that heavily doped Si performing high absorption/emissivity up to 0.9 in the 8-14μm spectral regime. In the experiment, the average emissivity of 0.69 at 8~13μm spectral regime was demonstrated. The result shows the radiation energy of heavily doped Si based IR emitter can be largely enhanced by the structure as well.

碩士<br>國立臺北科技大學<br>製造科技研究所<br>107<br>In recent times, a lot of effective steps are initiated by the research community to narrow down the size of standard desktop near-infrared spectrometer into the miniature size. So, it can be employed for the practical applications by the non-scientific community for the real-time non-destructive examinations especially the analysis of foodstuffs and health monitoring. The deteriorating availability of traditional light sources makes phosphor converted near-infrared light-emitting diode (pc-NIR LED) as a superior and auspicious light source candidate for miniature spectrometers. Moreover, the growing technology of pc-NIR LED also opens up the possibility of new applications areas like facial/iris recognition by smartphones, infrared cameras for security, LIDAR (light, imaging, detection, and ranging) technology and so on. The two different La-gallogermanate host crystal systems are reported in this thesis work. In the first work, La3Ga5(1-x)GeO14： 5xCr3+ (0.005 ≤x≤ 0.09) is reported with the super broadband NIR luminescence in the range of 650 to 1200 nm with the wide full width half maximum (fwhm) of 330 nm and radiant flux of 18.2 mW for the first time. The observation of super broadband luminescence from two distinct luminescence centers is studied and evidenced by structural and spectroscopy investigations. In the second work, the crystal structure of La3Ga1-xGe5O16：x Cr3+ (0.005 ≤x≤ 0.13) is solved for the the actual crystallographic sites of all elements by joint Rietveld refinement and achieved the ultra-broadband NIR luminescence in the range of 620 to 1020 nm with the hyper radiant flux of 43.1 mW at the driving current of 350 mA. Noteworthy, the radiant flux is increased to 56.3 mW and 65.2 mW by the modifications of chemical compositions as La3(1-y)Ga0.93Ge5O16: 0.07 Cr3+, 3y Gd3+ (0.005 ≤y≤ 0.02) and La2.97Ga0.93Ge5(1-z)O16: 0.07 Cr3+, 0.03 Gd3+, 5z Sn4+ (0.005 ≤z≤ 0.03) respectively. The presence of multiple-luminescent centers (multi-excited state) of Cr3+ resulted in broadening of the emission spectrum along with increased intensity. Finally, the luminescence mechanism of Cr3+ is discussed with the relevant configurational coordinate diagrams. Moreover, it is observed that the phosphor host system with a higher number of the crystallographic site for Cr3+ ions can promote higher fwhm but lesser radiant flux and vice versa.

Indiana University-Purdue University Indianapolis (IUPUI)<br>This clinical study investigated the efficacy of the new LED LCU technology when compared to that of the QTH LCU by evaluating retention and wear of Clinpro (3M ESPE) sealant material over six months of function. This study was designed as a split mouth, randomized clinical study. Sealants were placed and polymerized on contralateral teeth of 35 patients, 33 of which successfully completed the study. The sealants were evaluated for clinical retention at baseline, three months, and six months by two evaluators. For the wear analysis, the area of the sealant wear at six months is reported. Nine pairs of molars and 22 pairs of premolar teeth were used. This sample size is smaller than the original sample used for clinical evaluation, because a number of the baseline impressions had to be discarded due to poor impression quality. Subsequent impressions were taken at three months, and six months. Epoxy replicas were made from the impressions and the occlusal surface of each replica was digitized using SigmaScan software. A cummulative legit model was applied to the clinical data, and a linear model was applied to the wear analysis. The results for clinical retention over the six months of function were as follows. At Baseline, for the QTH, 97.3 percent of the teeth received an Alpha score; 2.7 percent received a score of B. For the LED, 87.7 percent received a score of A; 12.3 percent received a score of B. At three months follow-up, for the QTH, 93.1 percent received a score of A; 6.9 percent received a score of B. For the LED, 86.1 percent received a score of A; 12.5 percent received a score of B, and 1.14 percent received a score of C. At six months follow-up, for QTH; 91.7 percent received a score of A; 8.3 percent received a score of B. For the LED, 83.3 percent received a score of A; 15.3 percent received a score of B, and 1.14 percent received a score of C. The hypothesis was that there would be no significant difference in clinical retention and wear of Clinpro's sealant polymerized with the QTH or the LED light sources over six months of function. Based on the results of this clinical study, the following conclusions can be made: 1) At baseline, Clinpro's sealant polymerized with QTH light source showed marginally significant better retention than LED light source (p-value 0.05001). 2) There was no significant difference between light sources for sealant clinical retention at three-month and six-month follow up visits. 3) Wear analysis resulted in marginally significant more wear for molar sealants polymerized with LED LCU (p-value 0.0755). 4) Wear analysis showed no significant difference for premolar sealants polymerized with either light source.

To investigate quantum confinement effects on silicon (Si) light source electroluminescence (EL) properties like quantum efficiency, external power efficiency and spectral emission, thin Si finger junctions with nanometre-scale dimensions were designed and manufactured in a fully customized silicon-on-insulator (SOI) semiconductor production technology. Since commonly available photolithography is unusable to consistently define and align nanometre-scale line-widths accurately and electron-beam lithography (EBL) by itself is too time-expensive to expose complete wafers, the wafer manufacturing process employed a selective combination of photolithography and EBL. The SOI wafers were manufactured in the clean-rooms of both the Carl and Emily Fuchs Institute for Microelectronics (CEFIM) at the University of Pretoria (UP) and the Georgia Institute of Technology’s Microelectronic Research Centre (MiRC), which made a JEOL JBX-9300FS electron-beam pattern generator (EPG) available. As far as is known this was the first project in South Africa (and possibly at the MiRC) that employed EBL to define functional nanometre-scale semiconductor devices. Since no standard process recipe could be employed, the complete design and manufacturing process was based on self-obtained equipment characterization data and material properties. The manufacturing process was unprecedented in both the CEFIM and MiRC clean-rooms. The manufacture of nanometre-scale Si finger junctions not only approached the manufacturing limits of the employed processing machinery, but also had to overcome undesirable physical effects that in larger-scale semiconductor manufacture usually are negligible. The device design, mask layout and manufacturing process therefore had to incorporate various material, equipment limitation and physical phenomena like impurity redistribution occurring during the physical manufacturing process. Although the complicated manufacturing process allowed many unexpected problems to occur, it was expected that at least the simple junction breakdown devices be functional and capable of delivering data regarding quantum confinement effects. Although due to design and processing oversights only 29 out of 505 measured SOI light sources were useful light emitters, the design and manufacture of the SOI light sources was successful in the sense that enough SOI light sources were available to conduct useful optical characterization measurements. In spite of the fact that the functional light sources did not achieve the desired horizontal (width) confinement, measured optical spectra of certain devices indicate that vertical (thickness) confinement had been achieved. All spectrometer-measured thickness-confined SOI light sources displayed a pronounced optical power for 600 nm < λ < 1 μm. The SOI light source with the highest optical power output emitted about 8 times more optical power around λ = 850 nm than a 0.35 μm bulk-CMOS avalanche light-source operating at the same current. Possible explanations for this effect are given. It was shown that the buried oxide (BOX) layer in a SOI process could be used to reflect about 25 % of the light that would usually be lost to downward radiation back up, thereby increasing the external power efficiency of SOI light sources. This document elaborates on the technical objectives, approach, chip and process design, physical wafer manufacture, production process control and measurement of the nanometre-scale SOI light sources. Copyright<br>Dissertation (MEng)--University of Pretoria, 2010.<br>Electrical, Electronic and Computer Engineering<br>unrestricted

碩士<br>國立中興大學<br>食品科學系<br>93<br>Abstract Taichung Sen 10 brown rice was used for this study. Brown rice was germinated by treating with either normal light or Far Infrared Rays (FIR) for eighteen or twenty-one hours inside 25℃ incubator. The slightly germinated brown rice dealt by freeze dries. The objective of this study was to evaluate the change of physicochemical properties and anti-oxidative activity of germinated brown rice induced by two source of light. Germination observed in all treatments. The water content was about 40% after germination and reduced would be to 5.83~6.24% after freeze dried. Meanwhile the water activity would be lower than 0.5. So, it could take control on the quality of rice. In addition, the increment of dry weight was about 8% The α-amylase activities of germinated brown rice treated with FIR were higher than with normal light and increased with the germinate time. And, the α-amylase activities of germ were higher than of kernel. There was no significant difference in reducing sugar and total dietary fiber. The quantities of necessary amino acid and GABA were raise after germination. The nutritive value of total storage proteins were increase significantly. Each FIR treatment and long time would consume the quantity of vitamin E. The chelating ability of ferrous and TEAC in rice and germ after FIR treatment showed the higher level than after normal light, and increased with germinate time. The scavenging ability of DPPH free radical and superoxide radical, as well as the reducing power were showed the same tendency that the value would increase with germinate time in rice kernel, and FIR treatment had the better results than the treatment of normal light. After FIR treatment with 21 hours could obtain the better result in all antioxidant ability.

Indiana University-Purdue University Indianapolis (IUPUI)<br>BACKGROUND The efficacy of sealants to aid in the prevention of pit and fissure caries is well documented. In order for the sealants to be effective, they must be placed properly and retained for as long as possible. Clinicians must be aware that the proper placement of sealants is technique-sensitive and must be well controlled in order to achieve the best results. This study aims to determine if certain variables have an effect on curing of the sealant material to a degree that would compromise its integrity, strength, and longevity. METHODS AND MATERIALS Two commonly used sealant materials Ultraseal XT (Ultradent Products Inc., South Jordan, UT) and Delton (Dentsply International, Woodbridge, Ontario, Canada) were chosen and tested for microhardness and abrasion resistance after they were polymerized. This study did not focus on the materials themselves, but rather the technique by which they were polymerized and what effect this had on the materials. Three separate light sources, a traditional halogen light (QHL 75, Dentsply International, Woodbridge, Ontario, Canada), and two newer LED lights (Ultralume LED, Ultradent Products Inc., South Jordan, UT; and 3M Freelight LED, 3M Corp, St Paul, MN) were used in this study. The materials were then cured with each light at each of three different distances: contact (0.5 mm), 2 mm, and 10 mm. The effects of light source variation and distance from the material at the time of polymerization was then evaluated for any significance to sealant placement technique. Specimens were tested for each variable combination of sealant material, light source, and distance between the two while curing. Six samples were tested for each variable grouping for abrasion resistance, and four separate san1ples were tested fron1 the san1e grouping for Knoop hardness. The results were analyzed for significance to determine if certain techniques are or could be beneficial or damaging to the quality of care provided by today's practitioners. RESULTS It was found that materials and light sources varied in combination and with different techniques (e.g., distance). In general, the top surface polymerized best when cured at a distance of 2 mm to 10 mm, while the bottom surface polymerized best at a distance of 0.5 mm. The halogen light consistently outperformed the two LED lights, with the 3M LED consistently producing the worst results. CONCLUSIONS The halogen curing light used in this study outperformed the LED lights in almost every category, despite the LED light manufacturer's claims of equality. For more reliable polymerization, the halogen light should be used. SIGNIFICANCE The practitioner must be aware of the material that he/she is using and how the chosen light source polymerizes that material. Manufacturers' claims and recommendations cannot be trusted to accurately produce the best results with every product on the market today, sometimes not even with the manufacturers' own products. It is crucial for practitioners to be well versed and knowledgeable about the products that they use, based on current research and not manufacturers' claims.

Cancer is a leading cause of death that affects millions of people across the globe each year. Photodynamic therapy (PDT) is a relatively new treatment approach for cancer in which anticancer drugs are activated by light at an appropriate wavelength to generate highly cytotoxic reactive oxygen species (ROS) and achieve tumor destruction. Compared with conventional chemo- and radiotherapy, PDT can be performed with minimal invasiveness, local targeting and reduced side effects. However, most of the currently available PDT drugs mainly absorb in the visible part of the spectrum, where light penetration depth into human tissues is very limited. Therefore, increasing the treatment depth of PDT has been considered to be an important approach to improve the effectiveness of PDT for treating larger and thicker tumor masses. In this thesis, we present our investigation into the potential of two-photon activated PDT (2-γ PDT), combination therapy of PDT and chemotherapy, and bioluminescence-activated PDT as a means to increase the treatment depth of this modality. In 2-γ PDT, the photosensitizing agents are activated through simultaneous absorption of two photons. This approach allows the use of near-infrared (NIR) light that can penetrate deeper into tissues and thus, has the potential of treating deep-seated tumors and reducing side effects, while the non-linear nature of two-photon excitation (TPE) may improve tumor targeting. We have evaluated the PDT efficacy of a second-generation photosensitizer derived from chlorophyll a, pyropheophorbide a methyl ester (MPPa), through both one- and two-photon activation. We observed that MPPa had high one-photon (1-γ PDT efficacy against both cisplatin-sensitive human cervical (HeLa) and cisplatin-resistant human lung (A549) and ovarian (NIH:OVCAR-3) cancer cells when activated by femtosecond (fs) laser pulses at 674 nm. At a low light dose of 0.06 J cm-2, the MPPa concentration required to produce a 50% cell killing effect (IC50) was determined to be 5.3 ± 0.3, 3.4 ± 0.3 and 3.6 ± 0.4 μM in HeLa, A549 and NIH:OVCAR-3 cells, respectively. More significantly, we also found that MPPa could be effectively activated at the optimal tissue-penetrating wavelength of 800 nm through TPE. At a light dose of 886 J cm-2, where no measurable photodamage was observed in the absence of MPPa, the IC50 values were measured to be 4.1 ± 0.3, 9.6 ± 1.0 and 1.6 ± 0.3 μM in HeLa, A549 and NIH:OVCAR-3 cells, respectively. We obtained corresponding LD50 (the light dose required to produce a 50% killing effect) values of 576 ± 13, 478 ± 18 and 360 ± 16 J cm-2 for 10 μM MPPa, which were approximately 3-5 times lower than the published 2-γ LD50 of Visudyne® and 20-30 times lower than that of Photofrin®. These results indicate that MPPa may serve as a photosensitizer for both 1- and 2-γ activated PDT treatment of difficult-to-treat tumors by conventional therapies. Indocyanine green (ICG), a dye having an absorption maximum near 800 nm, has been considered to be a potential NIR PDT agent. However, the PDT efficacy of ICG has been found to be very limited probably due to the low yield of cytotoxic ROS. In the present work, we have evaluated the combination effects of ICG-mediated PDT with conventional chemotherapy mediated by two types of chemotherapeutic drugs, namely the type II topoisomerase (TOPII) poisons etoposide (VP-16)/teniposide (VM-26) and the platinum-based drugs cisplatin (CDDP)/oxaliplatin (OXP). Synergistic enhancement of cytotoxicity and increased yields of DNA double strand breaks (DSBs) were observed in HeLa, A549 and NIH:OVCAR-3 cancer cells treated with the combination of ICG-PDT and VP-16. The presence of VP-16 during the laser irradiation process was found to be critical for producing a synergistic effect. An electron-transfer-based mechanism, in which ICG could increase the yield of highly cytotoxic VP-16 metabolites, was proposed for the observed synergistic effects, although direct spectroscopic detection of the reaction products was found to be very challenging. Moreover, we observed a much lower degree of synergy in the human normal fibroblast GM05757 cells than that in the three cancer cell lines investigated. Synergistic effects were also observed in A549 cells treated with the combination of ICG-PDT and VM-26 (i.e. an analog of VP-16). Furthermore, the combination of low-dose CDDP/OXP and ICG-PDT was demonstrated to produce an additive or synergistic effect in selected cancer cell lines. These preliminary results suggest that the combination of ICG-PDT with VP-16/VM-26 or CDDP/OXP chemotherapy may offer the advantages of enhancing the therapeutic effectiveness of ICG-PDT and lowering the side effects associated with the chemotherapeutic drugs. Bioluminescence, the generation of light in living organisms through chemical reactions, has been explored as an internal light source for PDT in recent years. This approach, in principle, does not suffer from the limited tissue penetration depth of light. In the present project, we have evaluated the effectiveness of luminol bioluminescence in activating the porphyrin photosensitizers meso-tetra(4-sulfonatophenyl)porphine dihydrochloride (TPPS4) and Fe(III) meso-tetra(4-sulfonatophenyl)porphine chloride (FeTPPS). The combination treatment induced significant killing of HeLa cells, while additive effects were observed in two normal human fibroblast cell lines (GM05757 and MRC-5). Our observations indicate that bioluminescence of luminol may generate sufficient light for intracellular activation of PDT sensitizers. Furthermore, the combination treatment may have intrinsic selectivity towards cancerous tissues. In summary, we have demonstrated effective killing of cancer cells by MPPa-mediated 1- and 2-γ PDT, combination of ICG-PDT and VP-16/VM-26 or CDDP/OXP chemotherapy, and bioluminescence of luminol activated PDT mediated by TPPS4/FeTPPS. These positive preliminary results indicate that all these three approaches have the potential of increasing the treatment depth of PDT and facilitating the development of more effective PDT treatment strategies.

Optics are a powerful probe of chemical structure that can often be linked to theoretical predictions, providing robustness as a measurement tool. Not only do optical interactions like second harmonic generation (SHG), single and two-photon excited fluorescence (TPEF), and infrared absorption provide chemical specificity at the molecular and macromolecular scale, but the ability to image enables mapping heterogeneous behavior across complex systems such as biological tissue. This thesis will discuss nonlinear and linear optics, leveraging theoretical predictions to provide frameworks for interpreting analytical measurement. In turn, the causal mechanistic understanding provided by these frameworks will enable structurally specific quantitative tools with a special emphasis on application in biological imaging. The thesis will begin with an introduction to 2nd order nonlinear optics and the polarization analysis thereof, covering both the Jones framework for polarization analysis and the design of experiment. Novel experimental architectures aimed at reducing 1/f noise in polarization analysis will be discussed, leveraging both rapid modulation in time through electro-optic modulators (Chapter 2), as well as fixed-optic spatial modulation approaches (Chapter 3). In addition, challenges in polarization-dependent imaging within turbid systems will be addressed with the discussion of a theoretical framework to model SHG occurring from unpolarized light (Chapter 4). The application of this framework to thick tissue imaging for analysis of collagen local structure can provide a method for characterizing changes in tissue morphology associated with some common cancers (Chapter 5). In addition to discussion of nonlinear optical phenomena, a novel mechanism for electric dipole allowed fluorescence-detected circular dichroism will be introduced (Chapter 6). Tackling challenges associated with label-free chemically specific imaging, the construction of a novel infrared hyperspectral microscope for chemical classification in complex mixtures will be presented (Chapter 7). The thesis will conclude with a discussion of the inherent disadvantages in taking the traditional paradigm of modeling and measuring chemistry separately and provide the multi-agent consensus equilibrium (MACE) framework as an alternative to the classic meet-in-the-middle approach (Chapter 8). Spanning topics from pure theoretical descriptions of light-matter interaction to full experimental work, this thesis aims to unify these two fronts. <br>