A THz spectrometer based on a CsI prism
J. Opt. A , Volume 10 - Issue Article number: 95303 p. 1- 7
A terahertz (THz) spectrometer is demonstrated that is based on a 25 K cryogenically cooled cesium iodide prism using a bolometer as detector. We present the THz spectrum of short pulses from a large biased semiconductor irradiated with femtosecond pulses from a Ti:sapphire laser and calibrate the spectrum with the transmission spectra of frequency-selective surface filters centered at 300 and 600 GHz. In addition, the optical properties (absorption and dispersion) in the THz frequency range are reported for CsI, and also KBr and KCl for temperatures between 10 and 300 K. These were obtained using THz time domain transmission spectroscopy using electro-optic sampling. The CsI prism spectrometer is sufficiently transparent from 0.2 to 1.1 THz, ensuring an overall energy throughput exceeding 10%. The resolution equals about 100 GHz at 0.6 THz and 170 GHz at 0.3 THz.