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Wavelength and polarization control for silicon photonic receiver applications

University of British Columbia

Wavelength and polarization are the fundamental and key properties of lightwave transmissions. Photonic integrated circuits (PICs) on silicon-on-insulator (SOI) provide a low-cost, large-scale, and on-chip solution for the increasingly demanding optical interconnects. This thesis presents a theoretical and experimental study on wavelength and polarization manipulations for silicon photonic receiver applications. Firstly, wavelength and polarization components in SOI platforms are demonstrated; then, active subsystems based on the developed components are proposed and tested, in which mathematical methods-based, automated control algorithms are also investigated. For the development of SOI components, first, narrow-band, Gaussian-apodized, spiral Bragg grating waveguides (SBGWs) are demonstrated for the use of wavelength filters. The fabricated apodized SBGWs perform smoother spectra with higher side-lobe suppression ratios, which prove that the applied apodization scheme can reduce the channel crosstalk of the multiple wavelength filters. Second, broadband, sub-wavelength grating (SWG)-assisted, adiabatic polarization splitter-rotators (PSRs) are experimentally demonstrated using an electron-beam lithography process and an optical lithography process, respectively. The SWG-PSRs are more compact than previously reported entirely adiabatic PSRs, and the PSRs fabricated using the optical lithography is the first implementation of an SWG-based structure in a standard, complementary metal-oxide semiconductor (CMOS) compatible fabrication process. For the active subsystems demonstration, an automated polarization receiver (PR), formed by the adiabatic components, is proposed to overcome any arbitrary input polarization state from a standard optical fiber. Through the fabricated PR, high-speed transmission experiments are implemented to demonstrate the automated control process. Four control algorithms - greedy linear descent-based, basic gradient descent-based, two-point step size gradient descent-based, and two-stage optimization method-based control algorithm are developed. We implemented high-speed experimental to achieve automated adaptations and compared the control algorithms' performance as regards the iteration number and the output responses. Then, automated wavelength and polarization control in a wavelength-division multiplexing polarization receiver (WDM PR) are developed. We have designed and fabricated a two-channel WDM PR to implement the automated control process. The demonstrated gradient descent-based control algorithm is utilized for the automated adaptations of any arbitrary input polarization states, and, simultaneously, used for the automated stabilization of the channels.

Text

2020-07-22

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/75248

Electrical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/