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The effect of age and traffic deposition on the spectral transmission of greenhouse glassSchoene, Sara E. January 1932 (has links)
M.S.
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Graphene-silicon waveguides as saturable absorbers in mode-locked fiber lasers.January 2013 (has links)
石墨烯,由單層碳原子緊密排列成蜂巢狀的晶體結構,擁有卓越的電學性能和光學性能。這些優異的性能包括:極高的電子遷移率,超寬的吸收光譜,栅電壓調控光躍遷性質,飽和吸收性質。石墨烯的獨特光學性質已經被用來製造多種高性能的光電器件,包括光電探測器, 飽和吸收器, 光調製器和四波混頻的介質。同時,石墨烯的製造工藝可以與現代半導體標準製造工藝相兼容, 加上它穩定的化學性質, 石墨烯非常有潛力在未來半導體工業發展中發揮重要作用。 / 單層石墨烯可以透過97.7% 垂直入射的光,吸收2.3% 左右,並且吸收的光頻非常寬。雖然對於單層碳原子結構,這個吸收率很大,但是在一些器件中,我們需要更高的光吸收率。爲了突破單層石墨烯光吸收的極限,一種可行的辦法是延長石墨烯與光相互作用的長度。將單層石墨烯轉移到長的硅波導上,可以延長石墨烯與光作用的長度。除了線性光吸收特性,石墨烯的飽和吸收特性也有廣泛的應用。很多脉衝激光發生器是利用被動鎖模的原理,即激光器中的飽和吸收器將連續的光波轉變成頻率固定的脉衝。石墨烯已經被證明是恢復速度快、調製範圍大的飽和吸收器。 但是,石墨烯和硅波導結合作為飽和吸收器的特性和它們的應用還從來沒有被研究過。 / 在論文中,我們研究了石墨烯轉移到硅波導后的線形光學性質和飽和吸收特性。首先我們討論了石墨烯轉移的方法,然後我們通過實驗調查了石墨烯在貴波導上的線形光學性質和飽和吸收特性。爲了研究石墨烯/硅波導在被動鎖模光纖激光器中的作用,我們利用石墨烯/硅波導作為飽和吸收器製造了一個光纖激光器。之後,通過在激光腔體中加入可调滤波器, 我們用成功的演示了波長可調製被動鎖模光纖激光器。 / 多脉衝激光光源在光纖通信,測量學和光學器件性能鑒定中有重要作用。所以研究緊湊、穩定並且價格實惠的多脉衝鎖模激光器非常有意義。爲了實現多脉衝鎖模光纖激光器,我們將硅基濾波器和石墨烯/硅波導集成在一起. 在論文中,我們設計并優化了能被應用於多脉衝鎖模激光器的寬帶寬濾波器凹凸光栅。 / Graphene, a single 2D sheet of carbon atoms arranged in a honeycomb lattice, has superior electrical and optical properties including extremely high charge-carrier mobility, broadband optical absorption, gate-variable optical transitions and saturable absorptions. Its unique optical properties have led to a range of promising optoelectronic devices, such as photo detectors, saturable absorbers, optical modulators and nonlinear media for four-wave mixing. Graphene’s complementary metal-oxide-semiconductor (CMOS) integration processes at wafer scale and its electrochemical stability make it a promising candidate for post CMOS electronics. / Monolayer grapheme transmits 97.7% of the normal incident light and absorbs 2.3%, independent of wavelength. In order to overcome the challenge of limited absorption of a monolayer and better exploit graphene optical properties, a long interaction length is needed. By integrating graphene directly on top of silicon waveguides, longer light/graphene interactions can be achieved. In addition to the linear optical properties of the graphene, its saturable absorption also finds useful applications. Many ultra-short pulse lasers are based on passive mode-locking, where a saturable absorber turns continuous wave output of the laser into a train of optical pulses. And graphene has been shown to make an excellent saturable absorber. However, the saturable absorption behavior of graphene-silicon wavguides and their applications have never been studied. / In this thesis, the linear and saturable absorption of monolayer graphene films transferred onto silicon waveguide are investigated. The transfer process of monolayer graphene to silicon waveguides is studied and linear and saturable absorption measurements are carried out. To investigate applications of graphene-silicon waveguides, a passive mode-lock fiber lasers in which graphene-silicon waveguides act as saturable absorbers to mode-lock pulses is constructed. By adding a tunable filter in cavity, a tunable mode-locked fiber laser based on graphene-silicon waveguide is demonstrated. / Multi-wavelength pulse sources are important for applications including optical fiber communication, instrumentation, and photonic component characterization. The availability of compact, reliable and cost effective multi-wavelength mode-locked lasers is of great importance. We also hope to build multiwavelength mode-locked fiber lasers by integrating CWDM silicon filters with graphene-silicon waveguides. The design process and optimization of a silicon filter called echelle grating is demonstrated. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Shi, Zerui. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Abstracts also in Chinese. / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Photonic Integrated Circuit (PIC) --- p.1 / Chapter 1.2 --- Silicon on Insulator (SOI) Photonics --- p.3 / Chapter 1.2.1 --- SOI Waveguides --- p.5 / Chapter 1.2.2 --- SOI Waveguide Based Wavelength Division Multiplexing --- p.6 / Chapter 1.3 --- Graphene Photonics --- p.9 / Chapter 1.3.1 --- Band Structure of Monolayer Graphene --- p.9 / Chapter 1.3.2 --- Optical Absorption of Graphene --- p.13 / Chapter 1.3.3 --- Graphene Based Passive Mode-Locked Fiber Lasers --- p.18 / Chapter 1.4 --- Motivation --- p.22 / Chapter 1.5 --- Thesis Outline --- p.23 / Chapter 1.6 --- Reference --- p.24 / Chapter Chapter 2: --- Optical Properties of Graphene-Silicon Waveguides --- p.27 / Chapter 2.1 --- Fabrication and Transfer Process of Graphene-Silicon Waveguides --- p.28 / Chapter 2.1.1 --- Fabrication of SOI Waveguides --- p.28 / Chapter 2.1.2 --- Transfer Process of Monolayer Graphene onto SOI Waveguides --- p.29 / Chapter 2.2 --- Linear Optical Absorption of Graphene-Silicon Waveguides --- p.35 / Chapter 2.2.1 --- Introduction to Photoexcitation in Monolayer Graphene --- p.35 / Chapter 2.2.2 --- Experimental Results of Linear Absorption --- p.37 / Chapter 2.3 --- In-Plane Saturable Absorption of Graphene-Silicon Waveguides --- p.38 / Chapter 2.3.1 --- Experimental Result of In-Plane Saturable Absorption of Graphene-Silicon Waveguides --- p.39 / Chapter 2.3.2 --- Mechanism of Saturable Absorption of Graphene-Silicon Waveguides --- p.42 / Chapter 2.4 --- Summary --- p.44 / Chapter 2.5 --- Reference --- p.45 / Chapter Chapter 3: --- Hybrid Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.47 / Chapter 3.1 --- Background of Graphene Based Mode-Locked Fiber Lasers --- p.47 / Chapter 3.1.1 --- Passive Mode-Locked Lasers Fundamentals --- p.47 / Chapter 3.1.2 --- Review of Recent Works of Graphene Based Mode-Locked Fiber Lasers . --- p.52 / Chapter 3.2 --- Hybrid Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.55 / Chapter 3.2.1 --- Experimental Set Up and Results --- p.55 / Chapter 3.2.2 --- Discussion --- p.59 / Chapter 3.3 --- Tunable Graphene-Silicon Waveguides Based Mode-Locked Fiber Lasers --- p.62 / Chapter 3.4 --- Summary --- p.66 / Chapter 3.5 --- Reference --- p.66 / Chapter Chapter 4: --- Conclusion and Future Work --- p.68 / Chapter 4.1 --- Conclusion --- p.68 / Chapter 4.2 --- Future Work --- p.69 / Chapter 4.2.1 --- Design and Simulation Results of Echelle Grating --- p.69 / Chapter 4.2.2 --- Optimization and Experiment Results of Echelle Gratings --- p.77 / Chapter 4.2.3 --- Integration of Echelle Grating with SOI Waveguides --- p.82 / Chapter 4.3 --- Summary --- p.84 / Chapter 4.4 --- Reference --- p.85 / Chapter APPENDIX A: --- PUBLICATION LIST --- p.86 / Chapter APPENDIX B: --- LIST OF FIGURES --- p.87 / Chapter APPENDIX C: --- LIST OF TABLES --- p.91 / Chapter APPENDIX D: --- atlab Code of Simulation of Echelle Grating --- p.92
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Development of nanohole-based sensors for early detection of ovarian cancerChou, Yu-Wei Andrew 26 June 2013 (has links)
Ovarian cancer has very high mortality because it is hard to diagnosis in early stages. Many ovarian cancer biomarkers (such as HE4, CA 125) are available and had been suggested as potential tools for early cancer detection. However, early cancer detection using serological markers will only become widely used if a new generation of sensors that can be handled in a clinical setting can be developed. A detection technology that is promising for miniaturization and integration in biomedical sensing devices is based on the phenomenon of the extraordinary light transmission (EOT) through arrays of nanoholes on metal films. EOT is an increase in light transmission observed at certain wavelengths that satisfy the surface plasmon resonance (SPR) condition of the nanostructure. The position of this resonance is affected by surface adsorption phenomenon, which is the basis for the biosensor. In this dissertation, the detection of the HE4 biomarker was demonstrated using EOT. The EOT-based detection was compared to two state-of-the-art analytical methods (ELISA and commercial SPR). Based on our experiments, it was found that ELISA has lowest detection limit, around 0.5 ng/mL for that particular protein (HE4). The detection limits for the commercial SPR, around 0.13 μg/mL was comparable to the nanohole-based detection limit, around 1.76 μg/mL. In contrast to ELISA, the SPR-based methods were label free, more time efficient, and more environmental friendly. An extra advantage of the nanohole scheme was that multiple samples could be analyzed simultaneously and in real time. Adsorption kinetic experiments were also performed to evaluate the rate constants of the HE4 binding to a surface coated with anti-HE4. The adsorption equilibrium constant for the HE4 – anti-HE4 system was determined to be (4.3 ± 2.1) x 107 M-1. / Graduate / 0487
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Die Wirbeltiernetzhaut als optisches Element - Untersuchung der Korrelation von Morphologie und LichttransmissionPrasse, Martina 03 February 2016 (has links) (PDF)
Diese Arbeit befasst sich mit der Lichttransmission im retinalen Gewebe. Aufgrund der inversen Konfiguration der Wirbeltiernetzhaut muss das ins Auge eintretende Licht zahlreiche Zellschichten durchdringen, bevor es von den Photorezeptoren detektiert wird. Die Autorin geht davon aus, dass die morphologische Heterogenität dieser Zellschichten mit einer optischen Heterogenität einhergeht, welche den Lichttransport zu den Photorezeptoren beeinflusst. In den Versuchsbeschreibungen wird erläutert, wie das native Netzhautgewebe von Meerschweinen verschiedenen osmotischen Stimuli ausgesetzt wurde, um morphologische Veränderungen zu provozieren. Durch die parallele Beobachtung der Durchmesser ausgewählter Zellen der äußeren und inneren Netzhaut, sowie der quantitativen Lichtdurchlässigkeit des Gewebes, konnte die Autorin die morphologischen Veränderungen zur retinalen Lichtdurchlässigkeit in Beziehung setzen. Die Ergebnisse zeigen, dass Zellschwellungen zu einer Erhöhung der quantitativen Lichtdurchlässigkeit und Zellschrumpfungen zu einer Verringerung dieser führen. Es werden folgende Schlüsse gezogen: Die osmotischen Stimuli bewirken Volumenregulationsprozesse, infolge derer sich lokale Brechungsindizes und Extinktionskoeffizienten ändern und die retinale Lichtdurchlässigkeit beeinflussen. Zudem konnte die Autorin durch Versuche mit nativen Primatennetzhäuten nachweisen, dass die Abbildungsqualität im Zentrum der Fovea centralis am besten ist, weil die inneren Netzhautschichten dort nicht vorhanden sind und das Licht direkt auf die Photorezeptoren trifft. Diese Arbeit zeigt, dass die Wirbeltiernetzhaut ein optisch aktives Medium ist, dessen Morphologie die Lichttransmission durch das Gewebe beeinflusst.
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Microstructure effects on light propagation in zinc-sulfide thin film waveguides.Himel, Marc David. January 1988 (has links)
The optical propagation losses resulting from the internal microstructure of ZnS thin films were investigated using a wavelength technique. Waveguide losses were determined by measuring the scattered light as a function of propagation distance along the film. Accurate measurements were obtained by using a technique we developed that employees a coherent fiber bundle to transfer the scattered light streak to a remote image plane that was scanned with an apertured photomultiplier tube. Microstructure effects on losses were found to dominate effects caused by substrate surface finish. The magnitude of the loss was found to depend upon two independent parameters: the average grain size of the polycrystalline films and the refractive index difference between ZnS and the interstitial material. Increasing the H₂O partial pressure led to lower losses as a result of reduced crystallite size, and a change in preferential crystallite orientation. A similar change in orientation was observed for films deposited onto heated substrates. Increasing the O₂ partial pressure during deposition also resulted in slightly lower waveguide losses, possibly as a result of void filling with ZnO. The modal dependence of the losses for ZnS films deposited at ambient temperature suggests that volume losses dominate surface losses for the lowest order mode while the ratio of surface to volume losses increases for higher order modes. By depositing ZnS onto substrates cooled with liquid nitrogen, adatom surface mobility was reduced which resulted in amorphous films. Losses were minimized (≤0.5 dB/cm at λ = 633 nm) for a substrate temperature of -50°C. These losses are lower than any previously reported for ZnS. However, further reduction of the substrate temperature resulted in an increase in tensile stress which eventually led to higher waveguide losses and crazing. The films deposited onto cooled substrates exhibited a low refractive index which indicates a low packing density and increased porosity. Differential water desorption, which is further evidence of increased porosity, was most noticeable in films with lower refractive indices when nonlinear prism coupling was attempted.
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Studies of Particles and Wave Propagation in Periodic and Quasiperiodic Nonlinear MediaSun, Ning, 1963- 05 1900 (has links)
This thesis examines the properties of transmission and transport of light and charged particles in periodic or quasiperiodic systems of solid state and optics, especially the nonlinear and external field effects and the dynamic properties of these systems.
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SURFACE PLASMON COUPLED SENSOR AND NANOLENSKo, Hyungduk 2009 May 1900 (has links)
This dissertation consists of two topics. One is a "Multi-pass Fiber Optic Surface
Plasmon Resonance Sensor (SPR)" and the other is a "Nano-metallic Surface Plasmon
Lens." Since both topics involved surface plasmon, the title of this dissertation is named
"Surface plasmon coupled sensor and nanolens."
For a multi-pass fiber optic SPR sensor, a fiber optic 4-pass SPR sensor coupled
with a field-assist capability for detecting an extremely low concentration of charged
particles is first demonstrated. The multipass feature increases the sensitivity by a factor
equal to the number of passes. The field-assist feature forces charged particles/molecules
to the SPR surface, increasing the sensitivity by an additional factor of about 100.
Overall, the sensitivity exceeds the one-pass SPR device by a factor of about 400. A 10
pM concentration of 47 nm diameter polystyrene (PS) latex beads and 1 ?M
concentration of salt dissolved in DI water were detected within a few seconds by the
combined system. The equivalent index resolution for atomic size corresponding to
ionized chlorine in salt is 10-8. This technique offers the potential for sensitive and fast
detection of biomolecules in a solution. Secondly, a 44-pass fiber optic surface plasmon
resonance (SPR) sensor coupled with a field-assist capability for measurement of refractive index change due to positive and negative ions is shown. The field-assist
feature forces ions to the SPR surface, causing the SPR signal response to change which
reflects a decrease or increase in refractive index depending on whether positive or
negative ions are being attracted to the surface. This technique offers the potential for the
sensitive detection of cations and anions in a solution.
For a nano-metallic surface plasmon lens, we analyze the transmission of a
normally incident plane wave through an Ag/dielectric layered concentric ring structure
using finite difference time domain (FDTD) analysis. The dependency of the
transmission efficiency on the refractive index in slit is studied. The numerical analysis
indicates that the focusing beyond diffraction limit is found even at the extended focal
length comparable to the distance of 7" from the exit plane using a circularly polarized
coherent plane wave, ?=405 nm. Especially, compared to an Ag-only structure, the Ag/
LiNbO3 structure amplifies the transmission power by a factor of 6. Therefore, this
Ag/dielectric layered lens has the potential for significantly higher resolution imaging
and optical data storage.
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Obtanção de fios em ligas cobre-magnésio para utilização em linhas de transmissão de energia elétrica / Obtention of copper-magnesium alloys wires used in electrical transmission linesFERNANDES, MARCOS G. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:33:59Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:16Z (GMT). No. of bitstreams: 0 / O objetivo desse trabalho foi o de obter-se fios de cobre em três composições químicas distintas da liga Cu-Mg a partir de cobre eletrolítico e de magnésio. Foram avaliadas as etapas envolvidas, começando com a fusão de botões em forno a arco na composição do eutético Cu-Mg, diluição destes botões em forno resistivo, vazamento em lingoteira de cobre, seguido de tratamento térmico de homogeneização em forno resistivo a 910 ºC por 2 h. Os tarugos foram posteriormente trabalhados mecanicamente por forjamento rotativo seguido de um passe final de acabamento por trefilação, para obtenção do fio. As análises químicas realizadas nos lingotes indicaram que a rota de preparação dos fios mostrou-se adequada aos estudos em escala de laboratório, suficiente para a confecção de fios com área de seção transversal de 4 mm2 por 10 m de comprimento, para cada composição de liga. Os fios foram caracterizados mecanicamente por ensaio de tração e de dureza após tratamento térmico de recristalização a 510 ºC por 1 h. Os fios também tiveram as condutividades elétricas medidas na condição recristalizada e os resultados foram comparados com dados experimentais da literatura. Os materiais obtidos mostraram-se adequados à utilização como fio condutor de energia elétrica. Os limites de escoamento e de resistência a tração tiveram seus valores melhorados com o aumento do teor de magnésio na liga, 11 % e 24 %, respectivamente, enquanto houve queda nos valores de condutividade elétrica para cerca de 60 % IACS (International Annealed Copper Standard). / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Lens autofluorescence:in aging and cataractous human lenses. Clinical applicabilitySiik, S. (Seppo) 21 May 1999 (has links)
Abstract
This study was carried out to investigate in vivo the changes
of the human lens autofluorescence (AF) with aging and cataractogenesis.
Measurements were performed in the blue-green AF range (495 nm/520
nm) using a fluorometer designed, built and now clinically tested
in our department.
43 random eyes of 43 healthy volunteers aged 6-86 years, five
of each decade, were studied for effects of aging and 84 eyes of
84 patients with cortical, nuclear, posterior subcapsular or mixed
lens opacities were studied for differences of various cataract
types. The results were compared with the back light scatter values
obtained by the commercially available Interzeag Lens Opacity Meter
701. Also AF and back light scatter of the lens were measured from
122 smoking males aged 57 to 76 years who participated in a cancer
prevention study. The results were compared with the widely used
subjective lens opacities classification system, LOCS III. In addition
data was collected from 30 randomly chosen eyes of as many subjects
with varying degrees of yellow-brown lens coloration in an otherwise
healthy eye. We studied the influence of lens yellowing expressed
by means of lens AF on visibility of retinal nerve fiber layer
in black-and-white images.
Lens AF profile consists of anterior and posterior peaks and
a central plateau. The height of the anterior peak was used as
a measure of the maximum AF value. The square root of the ratio
between the posterior and the anterior AF peaks was used for estimating
the lens transmission. Our technique was highly reproducible. The
coefficient of variation was 3.9% for maximum AF and 2.9% for
the lens transmission index.
Both the maximum AF and light scatter were exponentially increased
with age (r = 0.95 and 0.94, respectively; p < 0.0001).
According to the regression line of AF begins to increase in early
childhood. It appears by extrapolation to be absent at birth. In
contrast light scatter in the lens was present even in young children.
The lens transmission for blue-green light, determined from the
lens AF curve, was almost unchanging with age up to 60 years. Thereafter
it decreased rapidly and the interindividual variation increased.In
cataractous lenses the mean AF and scatter values differed statistically
significantly from those of age matched healthy controls. The highest
AF values were measured in nuclear cataracts where AF was also
related to visual acuity and an increasing yellow-brown colour
of the nucleus. About half of the total variation of the transmission
index values could be accounted for by changes in nuclear colour
as assessed by the LOCS III grading system. The transmission index
provided a more precise prediction about nuclear colour and opalescence
than age or light scatter did.
In cortical cataracts the AF curve was low and flattened and
the maximum AF value was significantly lower than in the age matched
control eyes. The highest light scatter values were measured from
cortical cataracts, but the correlation between LOCS III cortical
grades and light scatter values was rather weak.
Posterior subcapsular cataracts cannot be quantified either
with AF or with light scatter measurements. Lens yellowing, expressed
as lens AF, had an actual effect on retinal nerve fiber layer visibility.
AF measurements provided a better prediction about the visibility
score than age or visual acuity did.
The results of the present study indicate that the lens autofluorescence
measurement may be a useful additional tool together with a subjective
grading system in the follow-up of optical changes occurring in
the nuclear region of the lens.
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Die Wirbeltiernetzhaut als optisches Element - Untersuchung der Korrelation von Morphologie und LichttransmissionPrasse, Martina 07 January 2016 (has links)
Diese Arbeit befasst sich mit der Lichttransmission im retinalen Gewebe. Aufgrund der inversen Konfiguration der Wirbeltiernetzhaut muss das ins Auge eintretende Licht zahlreiche Zellschichten durchdringen, bevor es von den Photorezeptoren detektiert wird. Die Autorin geht davon aus, dass die morphologische Heterogenität dieser Zellschichten mit einer optischen Heterogenität einhergeht, welche den Lichttransport zu den Photorezeptoren beeinflusst. In den Versuchsbeschreibungen wird erläutert, wie das native Netzhautgewebe von Meerschweinen verschiedenen osmotischen Stimuli ausgesetzt wurde, um morphologische Veränderungen zu provozieren. Durch die parallele Beobachtung der Durchmesser ausgewählter Zellen der äußeren und inneren Netzhaut, sowie der quantitativen Lichtdurchlässigkeit des Gewebes, konnte die Autorin die morphologischen Veränderungen zur retinalen Lichtdurchlässigkeit in Beziehung setzen. Die Ergebnisse zeigen, dass Zellschwellungen zu einer Erhöhung der quantitativen Lichtdurchlässigkeit und Zellschrumpfungen zu einer Verringerung dieser führen. Es werden folgende Schlüsse gezogen: Die osmotischen Stimuli bewirken Volumenregulationsprozesse, infolge derer sich lokale Brechungsindizes und Extinktionskoeffizienten ändern und die retinale Lichtdurchlässigkeit beeinflussen. Zudem konnte die Autorin durch Versuche mit nativen Primatennetzhäuten nachweisen, dass die Abbildungsqualität im Zentrum der Fovea centralis am besten ist, weil die inneren Netzhautschichten dort nicht vorhanden sind und das Licht direkt auf die Photorezeptoren trifft. Diese Arbeit zeigt, dass die Wirbeltiernetzhaut ein optisch aktives Medium ist, dessen Morphologie die Lichttransmission durch das Gewebe beeinflusst.
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