High bandwidth laser-frequency-locking for wideband noise suppression

TL;DR

This paper presents an experimental implementation of a high-bandwidth laser frequency noise servo loop with a 3.5 MHz bandwidth, significantly improving wideband noise suppression for quantum sensing and other applications.

Contribution

The study demonstrates a novel FNSL with a loop bandwidth of 3.5 MHz, surpassing traditional limits, enabling broader noise suppression in laser systems.

Findings

Achieved 70 dB noise suppression over 100 kHz range

Implemented FNSL with 3.5 MHz bandwidth, higher than typical systems

Broad applicability in fields requiring wideband noise suppression

Abstract

Ultra-low frequency noise lasers have been widely used in laser-based experiments. Most narrow-linewidth lasers are implemented by actively suppressing their frequency noise through a frequency noise servo loop (FNSL). The loop bandwidths (LBW) of FNSLs are currently below megahertz, which is gradually tricky to meet application requirements, especially for wideband quantum sensing experiments. This article has experimentally implemented an FNSL with loop-delay-limited 3.5 MHz LBW, which is an order higher than the usual FNSLs. Using this FNSL, we achieved 70 dB laser frequency noise suppression over 100 kHz Fourier frequency range. This technology has broad applications in vast fields where wideband laser frequency noise suppression is inevitable.