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Doctor of Philosophy (PhD) / Photonic crystals are optical structures that contain a periodic modulation of their refractive index, allowing them to control light in recent years of an unprecedented capacity. Photonic crystals may take on a variety of configurations, in particular the photonic crystal cavity, which may “hold” light in small volumes comparable to the light’s wavelength. This capability to spatially confine light opens up countless possibilities to explore for research in telecommunications, quantum electrodynamics experiments and high-resolution sensor applications. However, the vast functionality potentially made available by photonic crystal cavities is limited due to the difficulty in redefining photonic crystal components once they are formed in their (typically) solid material. The work presented in this thesis investigates several approaches to overcome this issue by reconfiguring photonic crystal cavities.

In this thesis, S-bend waveguides and ring resonant filters with multimode interference (MMI) couplers have been designed and fabricated. The single-ring filters are designed to have free spectral ranges ( FSR's) of 33.3GHz, 40GHz and 50GHz. The FSR's of double-ring filters are 100GHz and 200GHz. The splitting ratios of the 9-

No description available.

Doctor of Philosophy (PhD) / Photonic crystals are optical structures that contain a periodic modulation of their refractive index, allowing them to control light in recent years of an unprecedented capacity. Photonic crystals may take on a variety of configurations, in particular the photonic crystal cavity, which may “hold” light in small volumes comparable to the light’s wavelength. This capability to spatially confine light opens up countless possibilities to explore for research in telecommunications, quantum electrodynamics experiments and high-resolution sensor applications. However, the vast functionality potentially made available by photonic crystal cavities is limited due to the difficulty in redefining photonic crystal components once they are formed in their (typically) solid material. The work presented in this thesis investigates several approaches to overcome this issue by reconfiguring photonic crystal cavities.

Microelectromechanical structures (MEMS) are used commercially in sensor applications and in recent years much research effort has been done to implement them in wireless communication. Electron beam lithography and other advancements in fabrication technology allowed to shrink the size of MEMS to nanomechanical systems (NEMS). Since NEMS are just a couple of 100 nm in size, highly integrated sensor applications are possible. Since NEMS consume only little energy, this will allow continuous monitoring of all the important functions in hospitals, in manufacturing plants, on aircrafts, or even within the human body. This thesis discusses the modeling of NEM resonators. Loss mechanisms of macroscale resonators, and how they apply to NEM resonators, will be reviewed. Electron beam lithography and the fabrication process of Silicon NEM resonator will be described. The emphasis of this work was to build a test setup for temperature dependant measurements. Therefore different feasible techniques to detect nanoscale vibration will be compared and the setup used in this work will be discussed. The successful detection of nanoscale vibration and preliminary results of the temperature dependence of the quality factor of a paddle resonator will be reported. A new approach to fabricate NEM resonator using electrofluidic assembly will be introduced. / Master of Science

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A passive wireless sensor is designed, fabricated and tested for the measurement of AC electric field in the vicinity of high voltage apparatus. This sensor is applicable in remote condition monitoring of high voltage apparatus where close distance measurements raises safety hazards for operators. The sensor is designed using a coaxial cavity resonator structure (in TEM mode) capacitively coupled to varactors. The resonance frequency of the sensor shifts corresponding to the capacitance variation of the varactors which in turn is perturbed by the external electric field. The electric field surrounding the apparatus induces a bias voltage over the terminals of the varactors. Therefore, the resonance frequency changes proportional to the inducing external electric field and correspondingly to the medium/high voltage. A printed circuit board on the top of the cavity provides coupling between the cavity and varactors and also between the varactors and the external field produced by the high voltage apparatus. The sensor structure is designed to resonate in the range of 2.4 GHz to 2.5 GHz of the industrial, scientific and medical (ISM) radio frequency band. A remote interrogation system identifies the instantaneous resonance frequency of the sensor by transmitting pulses of radio frequency (RF) signal and recording the ring back of the resonator. The ring back is down converted and analyzed to determine the resonance frequency of the sensor. Two possible applications of the sensor, i.e. voltage measurement and defect detection of insulators, are demonstrated by experimental results. / February 2017

The purpose of this thesis is to develop ring resonators with simple processes and integration. We used loop mirror as a reflector in the semiconductor lasers. In the material, a 1.55£gm symmetric quantum well InGaAsP epi-layer is used to fabricate the lasers. In device design, we designed four kinds of semiconductor lasers by using loop mirror and cleaved facet. The curvature radiuses are 160 and 260£gm that are presented to investigate bending loss and material loss. In the input/output we had an inclined 7 degree to avoid interference. We also designed another two semiconductor lasers by using ring resonator and cleaved facet. Applying the resonance characteristic of ring resonator can achieve wavelength selection and filtering. In fabrication process, we developed new etching technique. The ICP-RIE dry etching and wet etching method were used in the process. Fist we etched half of the total depth by ICP-RIE dry etching. And then the multi-step technique was used to approach the expecting depth. Beside, we had extra deep wet etching process in MMI. Finally, we used the etching solution HBr:HCl:H2O2:H2O =5:4:1:70 to smooth the sidewall and reduce the scattering loss. In device characteristic, we obtained differential quantum efficiency of 20£gW/mA for the 1000£gm straight waveguide laser. We can not observe laser characteristics for the loop mirror laser, partly because of the high loss in bending section.