Electro-optic sampling near zero optical transmission point

Abstract

Theoretical calculation and experimental demonstration indicate that there is an optimal position near the zero optical bias point in a crossed polarizer electro-optic sampling geometry. At this position, free-space electro-optic sampling with a ZnTe sensor crystal has the largest modulation depth for the detection of a weak (THz) modulated signal on a strong laser background. Electro-optic sampling of THz pulses with a modulation depth of 9% and a signal-to-noise ratio better than 50 000:1 is demonstrated.