Fisher information for far-field linear optical superresolution via homodyne or heterodyne detection in a higher-order local oscillator mode

Fan Yang, Ranjith Nair, Mankei Tsang, Christoph Simon, Alexander I. Lvovsky
2017 Physical Review A  
The distance between two point light sources is difficult to estimate if that distance is below the diffraction (Rayleigh's) resolution limit of the imaging device. A recently proposed technique enhances the precision of this estimation by exploiting the source-separation-dependent coupling of light into higher-order TEM modes, particularly the TEM_01 mode of the image. We theoretically analyze the estimation of the source separation by means of homodyne or heterodyne detection with a local
more » ... llator in the TEM_01 mode, which is maximally sensitive to the separation in the sub-Rayleigh regime. We calculate the per-photon Fisher information associated with this estimation and compare it with direct imaging. For thermal sources, the per-photon Fisher information depends on the average photon number per thermal mode of the image; it surpasses the Fisher information for direct imaging (in the interesting sub-Rayleigh regime) when the average photon number exceeds two for homodyne detection and four for heterodyne detection.
doi:10.1103/physreva.96.063829 fatcat:x6hz6jl3enb2fkze5cnib5i4rq