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arXiv · 2402.00259

Optimum classical beam position sensing

Wenhua He·Christos N. Gagatsos·Dalziel J. Wilson·Saikat Guha
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Abstract

Beam displacement measurements are widely used in optical sensing and communications; however, their performance is affected by numerous intrinsic and extrinsic factors including beam profile, propagation loss, and receiver architecture. Here we present a framework for designing a classically optimal beam displacement transceiver, using quantum estimation theory. We consider the canonical task of estimating the position of a diffraction-limited laser beam after passing through an apertured volume characterized by Fresnel-number product DF. As a rule of thumb, higher-order Gaussian modes provide more information about beam displacement, but are more sensitive to loss. Applying quantum Fisher information, we design mode combinations that optimally leverage this trade-off, and show that a greater than 10-fold improvement in precision is possible, relative to the fundamental mode, for a practically relevant DF = 100. We also show that this improvement is realizable with a variety of practical receiver architectures. Our findings extend previous works on lossless transceivers, may have immediate impact on applications such as atomic force microscopy and near-field optical communication, and pave the way towards globally optimal transceivers using non-classical laser fields.

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Wenhua He, Christos N. Gagatsos, Dalziel J. Wilson, Saikat Guha. 2024-02-01. Optimum classical beam position sensing. https://doi.org/10.1103/physrevapplied.22.l041004

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