High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser

Abstract

The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The pressure broadening and the pressure shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.

Temperature dependent nonlinear response of quantum cascade structures

“…Possible applications for sources in this frequency range are many, such as imaging [3] and spectroscopy [4]. In order to make these applications reality, compact and convenient systems operating over cryogenic temperatures are a necessity, and currently designs based on resonant phonon extraction [5] are the most promising.…”

Photonic crystal mode terahertz lasers

“…3 The terahertz quantum-cascade laser ͑QCL͒ ͑Ref. 4͒ is able to fulfill most of the requirements for these applications.…”

Gain recovery time in a terahertz quantum cascade laser

“…5 There has also been significant interest in understanding emission from QCLs in the time-domain, and the generation of pulses on ultrafast timescales. The integration of THzQCLs with time-domain spectroscopy (TDS) [6][7][8] techniques has allowed the measurement of the electric field of the laser emission with an extremely high time resolution.…”