Shot noise reduced terahertz detection via spectrally post-filtered electro-optic sampling

TL;DR

This paper introduces a spectral filtering technique in terahertz electro-optic sampling that significantly reduces quantum noise, enhancing the signal-to-noise ratio and improving detection sensitivity.

Contribution

The study demonstrates a novel spectral post-filtering method that reduces shot noise in terahertz detection, with experimental validation at 45 THz using AgGaS2.

Findings

Signal-to-noise ratio increased by a factor of 3 experimentally

Theoretical analysis predicts potential improvement factors over 5

Spectral filtering minimally affects the signal level

Abstract

In ultrabroadband terahertz electro-optic sampling, spectral filtering of the gate pulse can strongly reduce the quantum noise while the signal level is only weakly affected. The concept is tested for phase-matched electro-optic detection of field transients centered at 45 THz with 12-fs near-infrared gate pulses in AgGaS2. Our new approach increases the experimental signal-to-noise ratio by a factor of 3 compared to standard electro-optic sampling. Under certain conditions an improvement factor larger than 5 is predicted by our theoretical analysis.