Quantum-enhanced salinity and temperature sensing based on generalized Talbot effect and intensity-correlated twin beams

We have theoretically proposed and experimentally demonstrated a sandwich-type (single-mode–no-core–single-mode) fiber-optic sensing scheme integrating generalized Talbot effect and intensity-difference squeezing source. As a fundamental wave phenomenon, Talbot effect describes the periodic revivals of field patterns, and is ubiquitous across the wave systems. Based on this effect, we positioned the interference maximum at the sensing beam wavelength by accurately tuning the no-core fiber parameters. The signal and the idler beams generated from intensity-difference squeezing source constituted intensity-correlated twin beams, in which the signal beam can be viewed as sensing beam to respond to the external changes in real time, while the idler beam can be viewed as reference beam whose power was synchronously attenuated to maintain the existence of quantum correlation, thus enhancing signal-to-noise ratio (SNR). The results showed that the present scheme enhanced the SNR of salinity and temperature sensing by 1.27 dB and 1.16 dB, respectively, compared with classical dual-channel light source scheme. This enhancement significantly increases the measurement accuracy and stability of sensor in weak signal detection and complex noise environments.