Polarisation selective integrated silicon photonic devices

Klitis, Charalambos (2018) Polarisation selective integrated silicon photonic devices. PhD thesis, University of Glasgow.

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Abstract

The main objective of this thesis was the development of polarisation selective gratings in silicon-on-insulator (SOI) technology. These devices can find numerous applications in the design of highly performing optical filters and, more in general, in all those devices that require on-chip manipulation of the polarisation state. The development of these devices was preceded by the optimisation of several fabrication processes, such as lithography and dry etching, and the re-design of a number of key components such as inverse polymer tapers and metallic heaters for thermal tuning. This activity culminated into a very robust process flow for SOI devices, with repeatable propagation losses in the order of 1 dB/cm, heaters with a very high tuning efficiency of 12 mW per π phase shift and 2dB and 1dB waveguide-to-optical fibre coupling losses for the TE and TM polarised mode, respectively. The grating designs developed in this thesis consisted of periodic holes etched onto the top surface of the silicon optical waveguide. Such geometry overlaps strongly with the TM polarised mode only and does not introduce additional losses to the TE mode. The benefit and the additional functionalities provided by the top grating geometry was assessed on two different polarisation sensitive devices. The first consisted in a microring resonator with integrated gratings for the emission of optical vortex beams, for which the top gratings provided a route to engineer the polarisation state of the emitted beam. The second device was a Bragg grating filter, where the top grating allowed the demonstration of extinction ratio values as high as 60dB by filtering the residual TM mode generated by the strong polarisation scattering.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Silicon photonics, polarisation selective, Bragg Grattings, nanofabrication.
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Colleges/Schools: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Supervisor's Name: Sorel, Prof. Marc
Date of Award: 2018
Depositing User: Mr Charalambos Klitis
Unique ID: glathesis:2018-8725
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 06 Feb 2018 16:17
Last Modified: 09 Mar 2018 09:38
URI: http://theses.gla.ac.uk/id/eprint/8725

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