Enhancement in sensitivity of coherent anti-Stokes Raman spectroscopy via SU(1,1) interferometry

Abstract

The sensitivity of coherent anti-Stokes Raman spectroscopy (CARS) is limited by the shot-noise from the probe fields used for stimulation and the non-resonant background noise. We have investigated the performance of the squeezing-enhanced version of CARS under homodyne detection and sum-intensity detection schemes, compared with the shot-noise limit (SNL) and quantum Cramér-Rao bound (QCRB). Our analysis shows homodyne detection performs better than sum-intensity and known single-intensity detection scheme results. It also provides a broader working range and shows more robustness against internal photon losses and remarkably improved performance in the gain-imbalanced configuration of SU(1,1) interferometer. As a result, we expect that our findings will be useful in quantum sensing and imaging techniques.