Generation of Ultrastable Microwaves via Optical Frequency Division

TL;DR

This paper demonstrates a highly stable 10 GHz microwave generator using optical frequency division with a high-Q resonator, achieving low fractional instability comparable to cryogenic oscillators without the need for cryogenic cooling.

Contribution

It introduces a novel optical-to-microwave division method using a high-Q resonator and frequency comb, achieving ultrastable microwave signals at room temperature.

Findings

Fractional frequency instability <8e-16 at 1 second.

Produces 10 GHz signals comparable to cryogenic oscillators.

Applicable to radar, communications, and precision spectroscopy.

Abstract

There has been increased interest in the use and manipulation of optical fields to address challenging problems that have traditionally been approached with microwave electronics. Some examples that benefit from the low transmission loss, agile modulation and large bandwidths accessible with coherent optical systems include signal distribution, arbitrary waveform generation, and novel imaging. We extend these advantages to demonstrate a microwave generator based on a high-Q optical resonator and a frequency comb functioning as an optical-to-microwave divider. This provides a 10 GHz electrical signal with fractional frequency instability <8e-16 at 1 s, a value comparable to that produced by the best microwave oscillators, but without the need for cryogenic temperatures. Such a low-noise source can benefit radar systems, improve the bandwidth and resolution of communications and digital sampling systems, and be valuable for large baseline interferometry, precision spectroscopy and the realization of atomic time.