Time-Domain Terahertz Spectrometer with 1-18 THz Spectral Coverage Based on a Cr:ZnS Oscillator

Toward multi-octave spanning molecular spectroscopy, Cr:ZnS femtosecond oscillators are regarded among the most promising mid-infrared sources [1]. By employing nonlinear compression using a TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> plate [2], these oscillators provide carrier-envelope-phase stable single-cycle pulses at 2.2 μm and support highly efficient spectral down-conversion to the 3–12 μm spectral range [3]. Further bandwidth extension, ultimately reaching the sub-terahertz regime, is expected to enhance the reliability of molecular identification through vibrational spectroscopy. However, there are few reports on far-infrared to terahertz generation based on 2-micron femtosecond oscillators [4]. In this study, we present, for the first time, broadband terahertz generation and detection based on optical rectification from a Cr:ZnS femtosecond oscillator.