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UBC Theses and Dissertations

Photoconductive heater-detectors for photonic integrated circuits Mosquera, Connor


Electro-optic feedback control is an active research area within integrated photonics, where detection and tuning elements are used to dynamically control devices and circuits. However, the need for discrete control elements increases the number of electrical connections to a photonic chip, and can require large area on-chip to integrate. Therefore, a single element that can perform both detection and tuning would provide great benefit over their disjoint counterparts as photonic circuit density increases. Photoconductive heater-detectors (PCHD) have proven viable as a hybrid control and detection element, but the lack of models available make it unlikely for circuit designers to adopt them in their designs. We propose an empirical compact model for PCHDs based on measured results. Core electro-optic relationships are pulled from literature and empirically modeled. A compact model for the general structure of a PCHD is implemented in Lumerical INTERCONNECT using standard library elements populated with parameters specific to the n-doped PCHDs that were measured. The compact model is used in a variety of simulations and compared against measured results. We also demonstrate the design of a widely tunable ring-based silicon photonic notch filter. We present measured results demonstrating the device capability of tuning the filtering frequency, the free spectral range (two states), the optical bandwidth from 5 to 34 GHz, and the extinction ratio in excess of 30 dB, all independently of each other. We also provide circuit simulations using the PCHD model to demonstrate feedback loops used to automatically reconfigure the circuit based on specific spectral property optimizations. Lastly, we propose an advanced silicon photonic biosensor architecture for the detection of COVID-19 and other pathogens, enabled by PCHDs. By integrating the detector and tuner as a single element within the resonant cavity and operating in the O-band rather than the C-band, cheap single wavelength lasers can be used as an optical source rather than the standard sweepable lasers required to operate photonic biosensors. Simulated results of the sensor highlight the trade-off between environmental sensitivity and measured signal strength as the size of the sensing region increases.

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Attribution-NonCommercial-NoDerivatives 4.0 International