Automated turnkey microcomb for low-noise microwave synthesis

TL;DR

This paper demonstrates an automated, compact microcomb system capable of near quantum-limited low-noise microwave synthesis, suitable for field deployment in radar and communication systems.

Contribution

It introduces an automated turnkey microcomb device with high Q fiber resonator, achieving near quantum-limited phase noise in a compact size, advancing low-noise microwave synthesis technology.

Findings

Achieved phase noise of -80 to -148 dBc/Hz at various offsets

Operates at 10.1 GHz and 1.7 GHz with low SWaP-C

Demonstrated near quantum-limited noise performance

Abstract

Microresonator-based optical frequency comb (microcomb) has the potential to revolutionize the accuracy of frequency synthesizer in radar and communication applications. However, fundamental limit exists for low noise microcomb generation, especially in low size, weight, power and cost (SWaP-C) package. Here we resolve this limit, by the demonstration of an automated turnkey microcomb, operating close to its low quantum-limited phase noise, within a compact setup size of 85 mm * 90 mm * 25 mm. High quality factor fiber Fabry-Perot resonator (FFPR), with Q up to 4.0 * 10^9, is the key for both low quantum noise and pump noise limit, in the diode-pump case in a self-injection locking scheme. Low phase noise of -80 and -105 dBc/Hz at 100 Hz, -106 and -125 dBc/Hz at 1 kHz, -133 and -148 dBc/Hz at 10 kHz is achieved at 10.1 GHz and 1.7 GHz repetition frequencies, respectively. With the simultaneous automated turnkey, low-noise and direct-diode-pump capability, our microcomb is ready to be used as a low-noise frequency synthesizer with low SWaP-C and thus field deployability.