Signal-to-noise ratio improvement of photon counting using wavelength modulation spectroscopy

摘要

Photon counting has been widely used in weak light detection. However, the low signal-to-noise ratio (N~(1/2), N is the mean counts) significantly limits the detection sensitivity. In this letter, we present a method that uses wavelength modulation spectroscopy to improve the signal-to-noise ratio of photon counting. Five times improvement of signal-to-noise ratio in 1 Hz bandwidth at best has been obtained in 2f harmonic detection.