Application of Quartz Tuning Fork in Photodetector Based on Photothermal Effect

A photodetector with a commercial quartz tuning fork (QTF) based on photothermal effect was demonstrated. Unlike the commonly used thermosensitive elements, a QTF with the mechanical resonance ability and the piezoelectric effect was used to amplify the photothermal signal. Operating at the optimal operating distance and modulation signal duty ratio selected for the photodetector, the photodetector achieved a good linear response at the wavelength of 1550 nm and 980 nm. And the photoresponsivity of the photodetector reach up to 515 mV/mW at the wavelength of 1550 nm. More important, the detection sensitivity of 0.75 pW at 203 s integration time has been achieved by using the Allan deviation analysis.