Balanced SPADE detection for distance metrology
- URL: http://arxiv.org/abs/2206.05246v1
- Date: Wed, 8 Jun 2022 17:35:37 GMT
- Title: Balanced SPADE detection for distance metrology
- Authors: Luigi Santamaria, Deborah Pallotti, Mario Siciliani de Cumis, Daniele
Dequal, Cosmo Lupo
- Abstract summary: Routinely used for telecommunication, SPADE has been adopted to measure distances in the transverse plane.
We improve on these performances by exploiting, through balanced detection, the simultaneous information in the lowest HG modes.
To the best of our knowledge this is an improvement of one order of magnitude compared with best measurement of this type.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: We implement Hermite-Gaussian (HG) spatial-mode demultiplexing (SPADE),
boosted by homodyne detection, for high-precision measurements of the
transverse distance between two point-sources. Routinely used for
telecommunication, SPADE has been adopted to measure distances in the
transverse plane, demonstrating extraordinary performances. These measurements
are typically limited by cross-talk. Here we improve on these performances by
exploiting, through balanced detection, the simultaneous information contained
in the lowest HG modes. In a first set of measurements, we simulate a real
acquisition setup with large cross-talk between the channels. We show that
balanced detection allows us to suppress the effect of cross-talks, yielding a
resolution much below the Rayleigh limit, down to one hundredth of the FWHM. A
reproducibility test confirms the reliability of this setup. In a second set of
measurements, we repeat the experiment with an improved setup optimised for
minimal cross-talks. In this improved scenario we demonstrate precision down to
few thousands of the FWHM, with the power to resolve two sources within 0.0055
FWHM. To the best of our knowledge this is an improvement of one order of
magnitude compared with best measurement of this type.
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