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arXiv · 2505.20986

High-precision laser spectrum analyzer via digital decoherence

Zhongwang Pang·Chunyi Li·Hongfei Dai·Wenlin Li·Dongqi Song·Fei Meng·Yige Lin·Bo Wang
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Abstract

With the continuous advancement of laser technology, accurately evaluating the noise spectrum of high-performance lasers has become increasingly challenging. In this work, we demonstrate a high-precision laser spectrum analyzer based on the proposed digital decoherence method, which can precisely measure the frequency noise spectrum of sub-Hz linewidth lasers. In addition, it has broad wavelength compatibility, which enables convenient switching between lasers with different center wavelengths. Its performance is validated through measurements of ultra-stable lasers. Based on the measured frequency noise power spectral density, a beta-line linewidth is determined to be 570 mHz at 10-second observation time, and the minimum observable linewidth is calculated to be 133 mHz. The system's noise floor is evaluated to be 210 mHz beta-line linewidth at 25-second observation time, and a minimum observable linewidth of 39 mHz.

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Zhongwang Pang, Chunyi Li, Hongfei Dai, Wenlin Li, Dongqi Song, Fei Meng, Yige Lin, Bo Wang. 2025-05-27. High-precision laser spectrum analyzer via digital decoherence. https://arxiv.org/abs/2505.20986

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