Environmental & Climate Sciences Department Seminar

Selective detection of signal over noise is essential to measurement and signal processing. Time-frequency filtering has been the standard approach for the optimal detection of non-stationary signals. However, there is a fundamental tradeoff between the signal detection efficiency and the amount of undesirable noise detected simultaneously. By tailoring the nonlinear process in a lithium-niobate waveguide, we demonstrate highly selective detection of picosecond single photons against broadband noise overlapping temporally and spectrally but in orthogonal time-frequency modes, with performance well exceeding the theoretical limit of the optimized time-frequency filtering. To this end, our technique can achieve signal to noise exceeding by far what's possible with linear optics filters even in the presence of strong background noise, which are highly desirable for many atmospheric remote sensing and imaging applications. Here, we present some feasibility studies in connecting our mode selective detection technique for applications in atmospherics science. Our results and visions may lead to enhanced resolution, sensitivity and detection limit for atmospheric instruments such as lidar and disdrometer.