Investigation on resonator based modulators for silicon photonic applications

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Name of the Speaker: Suvarna Parvathy K V (EE18D416)
Guide: Dr. Bijoy krishna Das
Venue/Online meeting link: ESB-244 (Seminar Hall)
Date/Time: 29th November 2022, 3.00 pm

CMOS process compatible silicon photonics technology finds a variety of applications in the area of communication, sensing, biomedical, automotive etc. Optical interconnect for data centers has been one of the initial successes of the technology in the field of communications. Silicon photonics transceiver plays a vital role for low cost and low power optical interconnect solutions for catering to ever-increasing data traffic. The key component of the transceiver is a modulator, which encodes electrical data onto an optical carrier. High speed modulators have been implemented popularly by Mach-Zehnder Interferometer (MZI) or Microring resonator (MRR) configurations. Though MRR based modulators are wavelength selective (operable only around resonant wavelengths), they offer smaller footprint and lower energy consumption per bit. Microdisc resonator and ditributed Bragg reflector (DBR) based Fabry-Perot cavity can be good alternatives to MRR. However, they have been relatively less investigated. All these modulators are designed on the basis of thermo-optic and plasma dispersion effects; the former effect is typically used for phase correction/detuning whereas the latter effect is used for high speed modulation. Our literature survey reveals that plenty of scope is there to improve the figures of merit, especially in case of resonator based modulators since they are thermally unstable and exhibit bistability at higher optical power levels.

In this talk, we will discuss various methods to improve the performance of plasma dispersion modulator and the impact of high input optical power in resonator based modulators. We will also present the design, fabrication and characterization of a passive microdisc resonator, along with its thermo-optic behavior and optical bistability at high optical power levels.