Group Index Dependence on Launch Polarization and Bend Radius in Photonic Integrated Circuits

Kiefer, Leo

Student Work

Group Index Dependence on Launch Polarization and Bend Radius in Photonic Integrated Circuits

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By measuring the free spectral range (FSR) of microring resonators (MRRs) on a silicon-on-insulator (SOI) photonic integrated circuit (PIC), the group index of the 500 x 220 nm strip waveguides was computed. This was repeated across a wide range of wavelengths, linear launch polarization angles, and two different bend radii (30 μm and 60μm) to determine the dependence of group index on both the waveguide propagation mode and bend radius. The experimental data were compared to sets of simulated data generated from COMSOL models of the MRRs. Data analysis and error estimation were performed using a combination of Python, Igor Pro, Excel, and MATLAB. Care was taken to fully document the probe station operation procedure for the benefit of future researchers. The propagation mode tests yielded inconclusive results, as the TM00 waveguide mode was not detectable at any launch polarization angle. The bend radius tests suggested that waveguide bending had very little effect on group index, as the group indices from the 30 μm and 60 μm MRRs were practically identical.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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