Ultra-Low Noise Microwave Extraction from Fiber-Based Optical Frequency Comb

TL;DR

This paper presents an all-optical fiber method to generate ultra-low noise microwave signals using phase-locked erbium fiber lasers, achieving record low phase noise and high frequency stability.

Contribution

It introduces a fiber-based approach for ultra-low noise microwave generation with unprecedented phase noise and stability performance.

Findings

Generated 11.55 GHz microwave with -111 dBc/Hz phase noise at 1 Hz

Residual frequency instability below 2.3×10^(-16) at 1s

Stable operation over three days with 4×10^(-19) instability at 6.5×10^4 s

Abstract

In this letter, we report on all-optical fiber approach to the generation of ultra-low noise microwave signals. We make use of two erbium fiber mode-locked lasers phase locked to a common ultra-stable laser source to generate an 11.55 GHz signal with an unprecedented relative phase noise of -111 dBc/Hz at 1 Hz from the carrier.The residual frequency instability of the microwave signals derived from the two optical frequency combs is below 2.3 10^(-16) at 1s and about 4 10^(-19) at 6.5 10^(4)s (in 5 Hz bandwidth, three days continuous operation).