Quantum-Limited Optical Vector Analysis
Abstract
Optical Vector Analysers (OVA) are critical for emerging technologies such as integrated photonics and optical positioning. Achieving a sensitivity near the Standard Quantum Limit (SQL) while acquiring a wide spectrum allows an accurate measurement of targets that are fragile, non-linear, or that scatter most of the probe light away. Existing OVAs operate with a sensitivity orders of magnitude below the SQL. In this paper, we use a free-running interferometer with a frequency range of 20 THz as an OVA. We introduce novel methods to mitigate the phase noise and obtain a unit signal-to-noise ratio for powers at the fW level. We apply this technique towards quantifying the fabrication quality of microring resonators in thin-film Lithium Niobate. Our characterisation yields a signal-to-noise ratio above 1 with much less than 1 circulating photon and reveals a quality factor above 5 millions, unambiguously attributed to low internal losses.
Cite
@article{arxiv.2509.25950,
title = {Quantum-Limited Optical Vector Analysis},
author = {Karthik Dasigi and Pavel A. Dmitriev and Kah Jen Wo and Fumiya Hanamura and Lingda Kong and Steven Touzard},
journal= {arXiv preprint arXiv:2509.25950},
year = {2025}
}
Comments
5 pages, 4 figures