Numerical investigations on phase-diversity optical digital coherent receiver-based noncontact photoacoustic signal detection

Optical interferometry is promising for noncontact photoacoustic (PA) signal detection; however, the intensity detection of the interference signal makes the system insensitive and unreliable due to fluctuations in the optical path length difference. To address this, a noncontact PA signal detection utilizing an optical digital coherent receiver to acquire the entire quadrature components of the PA signal in self-homodyne mode is proposed and numerically investigated. Simulation results show that by applying a narrow bandwidth probe laser at a linewidth of 33 kHz, the signal SNR meets the requirement of a 12-bit quantizer together with 13-dB tolerance to extra-intensity noise.