High-efficiency broad-bandwidth sub-wavelength grating based fibre-chip coupler in SOI

We report a comprehensive study on the performance of uniform and non-uniform based subwavelength grating couplers in Silicon-on-Insulator. The two performance metrics, coupling efficiency and bandwidth enhancement and trade-offs is presented. We also present, design parameters to achieve high-efficiency and broadband operation based on the detailed study of various loss mechanisms in the grating. Based on the detailed analysis subwavelength grating coupler designs with efficiency as high as 84 % with a 1 dB bandwidth of 50 nm and 98 % with a 44 nm 1 dB bandwidth is presented

All-optical wavelength multicasting in quadruple resonance-split coupled Silicon microring cavity

We demonstrate an all-optical four-channel wavelength multicasting in a coupled Silicon microring resonator system. The scheme is based on two-photon absorption induced free carrier dispersion in Silicon. The coupled cavity facilitates resonance splitting that is utilized as individual channels for multicasting. Using the split resonances, we achieve an aggregate multicasted data rate of 48 Gbps (4X12 Gbps). Moreover, we also present a detailed analysis and performance of the multicasting architecture

Compact Broadband Low-Loss Taper for Coupling to a Silicon Nitride Photonic Wire

We demonstrate an ultra-compact waveguide taper in Silicon Nitride platform. The proposed taper provides a coupling-efficiency of 95% at a length of 19.5 um in comparison to the standard linear taper of length 50 um that connects a 10 um wide waveguide to a 1 um wide photonic wire. The taper has a spectral response > 75% spanning over 800 nm and resilience to fabrication variations; >200 nm change in taper and end waveguide width varies transmission by <5%. We experimentally demonstrate taper insertion loss of <0.1 dB/transition for a taper as short as 19.5 um, and reduces the footprint of the photonic device by 50.8% compared to the standard adiabatic taper. To the best of our knowledge, the proposed taper is the shortest waveguide taper ever reported in Silicon Nitride

Generation of tunable, high repetition rate optical frequency combs using on-chip silicon modulators

We experimentally demonstrate tunable, highly-stable frequency combs with high repetition-rates using a single, charge injection based silicon PN modulator. In this work, we demonstrate combs in the C-band with over 8 lines in a 20-dB bandwidth. We demonstrate continuous tuning of the center frequency in the C-band and tuning of the repetition-rate from 7.5GHz to 12.5GHz. We also demonstrate through simulations the potential for bandwidth scaling using an optimized silicon PIN modulator. We find that, the time varying free carrier absorption due to carrier injection, an undesirable effect in data modulators, assists here in enhancing flatness in the generated combs.Comment: 10 pages, 7 figure