DTA

Digital Theses Archive

 

Tesi etd-08242020-122125

Type of thesis
Master univ. I liv.
Author
BIBI, AISHA
URN
etd-08242020-122125
Title
Design and Characterization of a Silicon-Photonic Polarization Splitter Rotator for Sensing Applications
Structure
Istituto di Tecnologie della Comunicazione, dell'Informazione e della Percezione
Course
Corsi Alta Formazione - PHOTONIC INTEGRATED CIRCUITS, SENSORS AND NETWORKS (PIXNET)
Committee
relatore Prof.ssa OTON, CLAUDIO JOSE
Relatore Dott. MARIN, YISBEL
Relatore Dott. SYGLETOS, STYLIANOS
Relatore Dott. SERGEYEV, SERGEY
Relatore Prof.ssa FARALLI, STEFANO
Keywords
  • Lumerical
  • polarization diversity
  • Polarization Splitter Rotator.
  • silicon-photonics
Exam session start date
08/09/2020;
Availability
completa
Abstract
The main motivation behind the master thesis was to contribute towards the integrated Fiber Bragg Grating Interrogators by overcoming one of the main hurdles; need of polarization diversity. In order to achieve this objective, it was decided to design and characterize Polarization Splitter Rotators (PSR) based on silicon photonics. The designing section of the thesis provided insight to the relevant theoretical concepts while the experimental section clarified the working principle of PSRs, combined together they provided a complete understanding of this particular polarization diversity scheme.<br>A novel design was proposed with some advantages with respect to previous designs in terms of footprint and compatibility with foundry processes. The design consisted of three blocks: splitter, rotator and mode converter. The design was performed using 3D Finite Difference Time Domain (FDTD) simulations and the parameters were optimized using Particle Swarm Optimization (PSO) algorithms using the Lumerical software suite. The performance of the designed PSR was then assessed through simulations of transmission efficiency and robustness to fabrication errors. Simulated transmission efficiencies and crosstalk levels of the optimized devices were comparable to the state of the art. Regarding robustness to fabrication deviations, it was found that all the blocks were tolerant to geometrical deviations up to ±20nm, except for the rotator which showed a high sensitivity to waveguide height. <br>An already fabricated PSR based on a previous design was characterized. PSRs based on edge and grating coupling techniques were characterized using two separate setups. The performance of the PSRs was evaluated by measuring the polarization crosstalk and insertion loss. Comparison of these parameters of the characterized chip with the results of the reference design shows better results were obtained in the characterized chip, demonstrating the efficiency of the design. Results obtained from characterization done using the two different coupling techniques illustrated that the edge coupling technique based on the butt-coupling setup was not appropriate for accurate characterization because of polarization drift of the source and edge quality variability. However, this technique was used to demonstrate a polarization-diversity scheme of a ring resonator device.
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