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Title: A novel method of biosensing using a temperature invariant microring resonator
Author: Lydiate, Joseph
ISNI:       0000 0004 5990 7424
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2016
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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).
Supervisor: Halsall, Matthew Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Micro-ring Resonator ; Microwave Modulation ; Sensor Down-conversion ; Modulator