Counting the Cycles of Light using a Self-Referenced Optical Microresonator

TL;DR

This paper demonstrates a compact, microresonator-based optical frequency comb that is self-referenced, enabling precise optical frequency measurements and coherent linking of optical and microwave frequencies in a miniaturized device.

Contribution

The work introduces a self-referenced optical frequency comb generated in an ultra-high Q microresonator, extending optical frequency synthesis to chip-scale devices.

Findings

Achieved phase-coherent linking of 190 THz optical and 14 GHz microwave frequencies.

Generated a self-referenced optical frequency comb using a microresonator and nonlinear fiber.

Demonstrated precision optical frequency measurements with a compact microresonator.

Abstract

Phase coherently linking optical to radio frequencies with femtosecond mode-locked laser frequency combs enabled counting the cycles of light and is the basis of optical clocks, absolute frequency synthesis, tests of fundamental physics, and improved spectroscopy. Using an optical microresonator frequency comb to establish a coherent link between optical and microwave frequencies will extend optical frequency synthesis and measurements to areas requiring compact form factor, on chip integration and comb line spacing in the microwave regime, including coherent telecommunications, astrophysical spectrometer calibration or microwave photonics. Here we demonstrate a microwave to optical link with a microresonator. Using a temporal dissipative single soliton state in an ultra-high Q crystalline microresonator that is broadened in highly nonlinear fiber an optical frequency comb is generated that is self-referenced, allowing to phase coherently link a 190 THz optical carrier directly to a 14 GHz microwave frequency. Our work demonstrates precision optical frequency measurements can be realized with compact high Q microresonators.