Common-path spectral interferometry for single-shot terahertz electro-optics detection

We propose a common-path spectral interferometer for single- shot terahertz (THz) electro-optics (EO) detection, where a probe pulse pair with orthogonal polarizations and a relative time delay are generated by simply using a birefringent plate. One of them, as the object, transmits through a THz EO crystal with THz phase modulation, while the other goes through the crystal without any phase imposed by target the THz field as the reference. The coaxial propagation of the pulse pair can effectively reduce the noises due to mechanical vibrations, air turbulences, and temperature fluctuations in the traditional noncommon- path spectral interferometers. Our experiments show that, for a given target THz pulse field, the measured THz signals in a single-shot mode have a signal-to-noise ratio (SNR) of 41.2 with our THz common-path spectral interferometer, but 7.91 with a THz Mach-Zehnder spectral interferometer; thus, our design improves the SNR of the THz signal by about 5.2 times. (C) 2017 Optical Society of America