High-bandwidth Coherence Cloning using Optical-Phase-Locking Feedforward

TL;DR

This paper introduces a feedforward method for optical coherence cloning that surpasses feedback limitations, achieving high suppression of phase noise in laser systems for quantum and metrology applications.

Contribution

A novel feedforward architecture that improves high-frequency coherence cloning by overcoming feedback latency, compatible with existing optical phase locking setups.

Findings

Achieved over 30 dB phase noise suppression from 10 kHz to 10 MHz.

Demonstrated robustness through active stabilization of beat amplitude and phase.

Provided a hardware-efficient, scalable solution for high-fidelity coherent control.

Abstract

Ultra-narrow-linewidth lasers with suppressed high-frequency phase noise are critical for quantum control and precision metrology. While optical phase locking (OPL) is the standard technique for cloning the coherence of such sources, its effectiveness is often limited at high frequencies by feedback latency. We present a robust feedforward architecture that overcomes this limitation by recycling and demodulating the existing master-slave beat signal to drive a single electro-optic modulator for near-instantaneous noise cancellation. This approach eliminates the extraneous sidebands and transmission losses typical of more complex modulators. Through active stabilization of the beat amplitude and demodulation phase, we demonstrate robust suppression exceeding 30 dB from 10 kHz to 10 MHz. This hardware-efficient framework is readily compatible with standard OPL setups, offering a scalable solution for high-fidelity coherent control.