Errors in PDH offset locking due to spurious spectral features Article Swipe
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· 2025
· Open Access
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· DOI: https://doi.org/10.1364/oe.572595
The Pound-Drever-Hall (PDH) technique is widely used to stabilize the frequency of lasers. Here we report on a routinely underestimated source of error in PDH offset-locking: a shift in the lock point due to the unintended interaction between residual optical sidebands and higher-order spatial modes in misaligned Fabry-Pérot cavities. Significant frequency deviations—up to 50% of the cavity linewidth—can arise when the optical offset is obtained from a sinusoidally driven EOM. We measure this deviation experimentally, find agreement with a simple model, and show how a spectrally-pure frequency offset can reduce the deviation by an order of magnitude. Our findings draw attention to a systematic effect of importance to precision optical spectroscopy, optical clocks, and quantum information science.
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- Type
- article
- Language
- en
- Landing Page
- https://doi.org/10.1364/oe.572595
- OA Status
- gold
- References
- 24
- OpenAlex ID
- https://openalex.org/W4414844232