The goal of the thesis is to fabricate the integrated asymmetric Mach-Zehnder Interferometer and Optical waveguide Ring Resonator with simple fabrication process. A 1.49£gm symmetric quantum well InGaAlAs epitaxial wafer is used to fabricate the devices. In the asymmetric Mach-Zehnder Interferometer design, we design asymmetric straight waveguides with difference of optical path, and asymmetric bend waveguides with difference of curvature radius. By this design, we can observe the interference variation of output light by difference of optical path. Using these properties, it will get the index change caused by electric field and the loss of bend waveguide. In optical waveguide ring resonator design, we improve the problem of the length of original K=0.15 Multi-Mode Interference (MMI) by stepped-width waveguide. And we obtain different transmission spectrum by adjusting the splitting ratio of MMI couplers (K=0.85, 0.5, and 0.15) and cascading doudle rings. We apply K0=0.5, K1=0.15 and K2=0.5 MMIs to design and fabricate optical filters with square transmission spectrum. In fabrication process, we get smooth sidewall and highly perpendicularity waveguide by multi-step wet etch method. In order to reduce waveguide loss, we make deep etching for the outside of curve waveguide and MMI. Finally, we use polyimide to smooth out the sides of the ridge waveguides and evaporate metal pad over the polyimide.

In this thesis, we have established an optical measurement system to measure the device characteristics. We focus on the investigation of semiconductor optical amplifier, Fabry-Perot laser, and ring cavity filter. We used InP-based multiple quantum wells epitaxial wafer with modulation doping in the active layer. A 1.41 £gm symmetric InGaAlAs/InP quantum well structure is used to fabricate the optical waveguide ring resonator devices for the optical communication region at 1.55£gm wavelength. For the semiconductor optical amplifier and lasers, we designed two different types: Fabry-Perot Amplifier (FPA), and Traveling Wave Amplifier (TWA). The InGaAlAs-FPA structure has three lasing peaks at 1514 nm, 1528 nm, and 1544 nm. The InGaAlAs-TWA-a structure has only one peak at 1510 nm. The InGaAsP-TWA-b structure has a gross gain = 8.5 dB (wavelength = 1575 nm) at pumping current = 22 mA. We used Hakki-Paoli method and transparency current to calculate gain spectrum. For ring cavity filter, the optical spectrum has a FSR = 41.25 GHz.

The integrating cavity absorption meter (ICAM) has been used successfully to measure the low absorption coefficient of pure water. The ICAM produces an effective total path length of several meters or even longer, although the physical size of the instrument is only several centimeters. The long effective total path length ensures a high sensitivity that enables the ICAM to measure liquid mediums with low absorption. Compared to the conventional transmission type of instruments that were used to measure the same medium with the same path length, the ICAM eliminates the effect of scattering by introducing isotropic illumination in the medium, and consequently measures the true absorption coefficient of the medium in stead of the attenuation coefficient. The original ICAM was constructed with Spectralon and used in the wavelength range from 380 nm to 700 nm. Later studies showed that Spectralon is not suitable for measurements in the UV region because of its relatively lower reflectivity in this region and, even worse, the continuously decaying reflectivity under the exposure to UV radiation. Thus, we have developed a new way to construct the ICAM utilizing the material fumed silica. The resulting ICAM has a high sensitivity even in the UV region and doesn't have the deterioration problem. The measurement results from the new ICAM are in good agreement with the existing results. The absorption coefficients of pure water at wavelengths between 250 nm and 400 nm are presented here.

The purpose of this thesis is to design and fabricate cross-loop cavity filter. We fabricated optical filter by bended waveguide and 2x2 90-degree MMI crossing model. By this design, we get the power splitter with coupling coefficient is 0, 0.15, 0.5, 0.85. By MatFhcad and BPM simulation, we showed that the device volume was decrease to 34%. In the quantum dot lasers, we fabricated the Fabry-Perot laser by optical waveguide and cleavage surface. In the material, a 1.3£gm quantum dots InGaAs epitaxial wafer is used to fabricate the lasers. Broad area lasers and ridge waveguide lasers are fabricated and their static properties (IV, LI) are analyzed experimentally. In fabrication process, first, we defined the device pattern by using photo-lithography technique. Second, we etched ridge waveguide by using dry etching method. Finally, we used the etching solution HBr:HCl:H2O2:H2O=5:4:1:70 to smooth the sidewall and reduce the scattering loss. We showed that the waveguide loss was decrease to 27.9dB/cm. In the QD lasers characteristic, we can not observe laser characteristics, partly because of the low optical power. Through the optimization of QD growth conditions, we can increase the QD sheet density and increase the number of QD layers. We can also optimize the device processing techniques and laser structure design in order to reduce the series resistance and to increase the optical confinement factor. By using the methods mentioned above, we believe the laser signal can be further increase. In the cross-loop cavity filter characteristic, we get the FSR=300GHz (simulation value FSR=50GHz) in throughput port and drop port. We attribute this appearance induced by cross couple for 2x2 90-degree MMI. The contracts for the drop port of 10.22dB have been achieved.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xii, 127 p. : ill., map (part col.). Includes abstract. Includes bibliographical references.

Thesis (Ph.D.)--York University, 2008. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 143-152). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR38991

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This thesis presents a novel method to fabricate metallic nanostructures on whispering gallery mode (WGM) cavity surfaces. The unique properties of WGM cavities have shown their promising future in both fundamental research and engineering applications. High sensitivity biosensors are one of the most important applications. Thanks to their ultra high quality factor (Q) and small optical mode volume, the resonant frequency shift of a single nanoparticle binding becomes detectable. The basic principles of a WGM cavity and its coupling mechanism with an optical coupler are discussed in detail. From the WGM sensing principle, people have demonstrated the positive contributions of the surface plasmon to the sensitivity. Furthermore, we implement the localized surface plasmon resonance (LSPR) on the cavity surface by depositing metallic dots. We use the focused ion beam (FIB) to directly deposit metallic nanodots on the spherical cavity surface for the first time. The quality factor of the cavity with metallic dots is above 10^7 in both air and water, which is more than one order larger than other published results. Also, the new method is much more controllable and repeatable than previous methods. It reveals a new fabrication method for potential ultra sensitive sensors based on WGM cavities. In addition, we offer a new mode solver for the toroidal WGM cavity. The microtoroid is a better platform for further investigation of WGM sensing than the microsphere. By expanding cavity modes to a set of normal fiber modes, we formulate the new mode solver based on simple physical principles. The simulation results of the radiative quality factor based on the new mode solver are presented as well. / Graduate

A system for exciting Rubidium atoms to Rydberg states has been constructed to study the interactions between them and metal surfaces. This thesis describes a method to reach the f Rydberg series using diode lasers. Since the diode lasers need to be frequency stabilized for this excitation, a transfer cavity stabilization method was implemented using the Pound-Drever-Hall technique. To obtain the necessary frequency modulation the diode laser was current modulated at ∼ 6 MHz. A noise cancellation circuit was used to suppress detection of the accompanying residual intensity modulation.

Thesis (M.S.)--University of Michigan, 1964.