High Resolution Terahertz Spectroscopy with Quantum Cascade Lasers

Abstract

Paper published as part of the special topic on Advances in Terahertz Solid-State Physics and Devices ARTICLES YOU MAY BE INTERESTED IN On-chip mid-infrared and THz frequency combs for spectroscopy

Application of Superconducting Hot-Electron Bolometer Mixers for Terahertz-Band Astronomy

“…For THz-band imaging based on heterodyne spectroscopy in astronomy, the quantum cascade laser (QCL) is one of the most promising compact, high-power CW LO sources (e.g. [54], [55]). Recently, 1-5 THz band submilliwatt-class CW emissions have been demonstrated using metal-metal (MM) and semi-insulation-surfaceplasmon (SI-SP) waveguide type QCLs based on chirped superlattice (CSL), bound-to-continuum (BTC), and resonant phonon (RP) active regions [55]- [58].…”

A Terahertz VRT spectrometer employing quantum cascade lasers

“…One notable advance has been the development of Quantum Cascade Lasers (QCLs) that function in the low Terahertz regime (1.2-5 THz). These devices offer many attractive features for spectroscopy, such as high power, narrow bandwidth, and continuous tunability over a broad spectral range [10][11][12][13]. While the advent of QCLs has greatly impacted infrared spectroscopy [14], only recently have commercial Terahertz QCLs become available to the general scientific community, and these have primarily been employed for imaging technologies [15][16][17][18].…”

Terahertz Frequency Metrology for Spectroscopic Applications: a Review

“…Despite the high complexity, the high electrical power consumption, and the very low efficiency with a few pW radiation powers, such kinds of sources provide a very narrow and absolute-frequency reference, suitable for mixing with the THz QCL in a sensitive detector such as a hot-electron bolometer. Frequency-locking of a THz QCL to a molecular reference was demonstrated in a first-derivative, direct absorption spectroscopy configuration, without any significant narrowing of the QCL emission [25][26][27]. Phase-locking to an optical FCS (OFCS) was achieved only recently [28] by locking a 2.5-THz QCL to the nth harmonic of the repetition rate of a mode-locked erbium-doped fiber laser.…”