Micro-ring devices are based on resonance principle and inherently are wavelength selective. Thus it is an important optical component for WDM based applications. To fully utilize the available capacity in an optical network, large full spectral range (FSR) and narrow passband are key performance targets of ring device designs. In this paper we report the design and analysis results of micro-ring filters with 4000+ GHz FSR and 25 to 50 GHz passband, based on symmetric add-drop filter structure. We optimize the passband shape (using a box-like factor), drop loss coefficient and off-resonance through loss via the coupling coefficients and ring loss parameters.

In this thesis, simulations of two novel features of a serially cascaded micro-ring resonator are presented. The thesis firstly describes the simulation of a novel, silicon on insulator (SOI) method to determine the refractive index change of a covering analyte by the extraction of the refractive index change information in the time domain. Secondly a novel arrangement of the serially cascaded micro-rings has the effect of producing a null instead of a peak in the Vernier enhanced resonant spectrum. The null feature, as well as the enhanced sensitivity of the sensor, allows the sensor to be used as an intensity interrogating device. The development of these applications using ring resonator physics is achievable, out-of-lab, by the application of photonic software. Finite difference time domain (FDTD), beam propagation method (BPM), finite element(FE) and eigenmode expansion (EME) methods were all used in the simulated development of the sensor. As a result of the dual ring resonator arrangement, the temporal output undergoes a wavelength (or frequency) shift from the micrometre (or TeraHertz) to the centimeter (or GigaHertz) range of frequencies. This allows the refractive index information to become available for transmission in the cm wavelength range over a standard wireless network. The latter could be realized by integration of a photo-detector and antenna into the final design. The sensor output is invariant to any structural or temperature changes applied to both rings. Two sensors based on the same design, but having different fabrication methods, are simulated. Models of the rib and ridge structures are realized by using optical simulation software. The data obtained from these simulations are then used to plot the ring resonator outputs in MATLAB. The design can be applied for either bulk (homogeneous) or surface sensing. Only homogeneous sensing, in the form of a uniform refractive index cover change, is simulated in this thesis. The spectral sensitivity of the rib based design, without Vernier enhancement, is 87.65nmRIU-1, while the spectral sensitivity of the ridge waveguide, without Vernier enhancement, is 422nmRIU-1. The Vernier enhanced spectral sensitivity of the rib design is 6415nmRIU-1 and the limit of detection is 12.47x10-6 RIU. The temporal sensitivity of the ridge is 1.9418μsec RIU-1. The rib temporal sensitivity was not calculated but it is expected to be ~ five times less sensitive than the non Vernier enhanced ridge design. Titanium Nitride (TiN) heaters were also included over the coupling regions of the dual ring resonators. The effect of the heaters on the dual ring resonant wavelength and on the single ring spectral shift were also simulated using a multi-physics utility of the applied FEM and BPM software. With the heater at 1.28μm above the resonator coupling waveguides, a single ring spectral shift of 717pm was exhibited by this simulation. For the heater positioned at 250nm above the coupling waveguides, a single ring spectral shift of 2.89nm was exhibited. Finally the fabricated designs, which are based on the models of the simulation data, were characterized and the results compared to the predicted outputs generated by the models of the Temperature Invariant Modulated Output Sensor (TIMOS).

Silicon-on-Insulator (SOI) micro-ring resonators (MRRs) are versatile elements in high-density integrated optics telecommunication systems. However, small inaccuracies in the fabrication process intensely deteriorate the response of SOI MRRs. By utilizing the racetrack resonator structures with strong coupling abilities, one can improve the fabrication tolerance. For the SOI racetrack resonators, the FSR is usually large. By introducing gratings into SOI racetrack resonators, the mutual mode coupling between the clockwise and counterclockwise modes can be induced and result in the resonance splitting. The grating-assisted SOI racetrack resonators can increase the operation wavelength and open up the possibility to overcome this limitation. In this thesis, we first use the 2-D FDTD method with the effective index method (EIM) to obtain the transmission spectra of the SOI racetrack resonators. The transmission spectra are then fitted by using the time-domain coupled mode theory (CMT) to obtain the quality factor and optical parameters of the SOI racetrack resonators. Next, we demonstrate the characteristics of mode splitting resulted from the mutual mode coupling between the clockwise and counterclockwise modes in the grating-assisted racetrack resonators by utilizing both the CMT and the 2-D FDTD method with the EIM. By tuning the grating configurations, such as the length or the structure of sidewall gratings, one can obtain the desired transmission spectrum of the grating-assisted racetrack resonators. Finally, we numerically investigate the temperature-dependent spectral characterics of the grating-assisted SOI racetrack resonator by taking the thermal-optic responce of the SOI materials into account. The thermal sensitivity of this device is 95.38 pm/¢XC, and the calculted properties can help the further designs based on the grating-assisted SOI racetrack resonators.

<div>Atoms trapped in close proximity to optical resonators provides a powerful tool for exploring atom light interactions and their quantum applications. In this work I will describe the development of a neutral atom quantum simulator that implements trapped cesium atoms which have been localized via optical tweezers in close proximity to the surface of a micro-ring resonator fabricated on the surface of an optical chip. The small separation between the cavity and the atom allows for relatively large atom photon coupling strength g on the order of a few hundred MHz. Coupling multiple atoms to a common nanophotonic mode provides a channel through which atoms can exchange virtual photons for the study of long range spin exchange and other quantum many body models.</div><div></div><div>This platform has proven to be extremely versatile. We have thus far successfully demonstrated our ability to trap and image individual atoms directly above the surface of our photonic chips as well as the ability to extend trapping and imaging to arrays of tweezer traps which can be loaded with one or more atoms with high probability. Due to the simplified fabrication process of our planar geometry photonic chips we have been able to rapidly prototype and evolve our system to facilitate new and improved methods of trapping atoms near the surface of our nanophotonic structure. In the following I will discuss the development of our apparatus, our current progress observing signatures of atom-cavity coupling, and some of our future goals we are approaching.</div>

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The ever-increasing bandwidth requirements to support telecommunications infrastructure necessitates large-scale fabrication of low-cost and scalable silicon photonic integrated circuits. Wavelength-division multiplexing (WDM) schemes are fundamentally limited in the number of channels supported in long-haul transmission by the erbium doped fiber amplifier (EDFA). To address this, researchers have turned focus toward the thulium doped fiber amplifier (TDFA), which provides 3× more bandwidth. This thesis describes the development of high-speed silicon-on-insulator (SOI) micro-ring resonator (MRR) modulators optimized for wavelengths in the TDFA band. Chapter 2 presents a theoretical performance comparison between MRR modulators designed for optimized use at EDFA and TDFA wavelengths. Chapter 3 presents an experimental study of optical loss mechanisms at extended wavelengths which suggests reduced waveguide scattering and enhanced divacancy defect absorption as well as larger bending and substrate leakage losses when compared with shorter wavelengths. An electronic variable optical attenuator is characterized in Chapter 4 to experimentally verify the predicted 1.7× TDFA-band free-carrier effect enhancement over EDFA-band wavelengths. The first steady-state operation of an MMR modulator near a central wavelength of 1.97 µm is also demonstrated under the enhanced free-carrier effect. Chapter 5 demonstrates the first high-speed reverse bias operation of an MRR modulator with a measured bandwidth of 12.5 GHz, and an on-chip optical link consisting of a modulator followed by a defectmediated detector with open eye-diagrams up to data rates of 12.5 Gbps. Chapter 6 introduces an electrically-driven post-fabrication defect-assisted resonance trimming technique via local annealing for use in MRR devices. Chapter 7 presents a Monte Carlo simulation of resonance alignment in multi-MRR systems subjected to spatially-correlated wafer variation created through the Virtual Wafer Model process to predict thermal power consumption and power reduction through resonance trimming. / Thesis / Doctor of Philosophy (PhD)

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