Microwave and RF Applications for Micro-resonator based Frequency Combs

TL;DR

This paper reviews recent advances in CMOS-compatible micro-resonator based frequency combs for RF and microwave applications, highlighting their potential for on-chip optical processing and the challenges in practical implementation.

Contribution

It introduces a new integrated frequency comb platform based on doped-silica glass microrings and demonstrates a broadband RF quadrature filter with high tap count and wide bandwidth.

Findings

Demonstrated a broadband microwave quadrature filter with over 5-octave bandwidth.

Used a CMOS-compatible doped-silica glass microring resonator for comb generation.

Achieved filters with up to 20 taps for advanced RF signal processing.

Abstract

Photonic integrated circuits that exploit nonlinear optics in order to generate and process signals all-optically have achieved performance far superior to that possible electronically - particularly with respect to speed. We review the recent achievements based in new CMOS-compatible platforms that are better suited than SOI for nonlinear optics, focusing on radio frequency (RF) and microwave based applications that exploit micro-resonator based frequency combs. We highlight their potential as well as the challenges to achieving practical solutions for many key applications. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement. We review recent work on a photonic RF Hilbert transformer for broadband microwave in-phase and quadrature-phase generation based on an integrated frequency optical comb. The comb is generated using a nonlinear microring resonator based on a CMOS compatible, high-index contrast, doped-silica glass platform. The high quality and large frequency spacing of the comb enables filters with up to 20 taps, allowing us to demonstrate a quadrature filter with more than a 5-octave (3 dB) bandwidth and an almost uniform phase response.