Integrated injection seeded THz source and amplifier for time-domain spectroscopy

Abstract

A terahertz (THz) frequency quantum cascade laser (QCL) is used as an integrated injection seeded source and amplifier for use in THz time-domain spectroscopy. A THz input pulse is generated inside a QCL, by illuminating the laser facet with a near-infrared pulse from a femtosecond laser, and amplified using gain switching. The THz output from the QCL is found to saturate upon increasing the amplitude of the THz input power, which indicates that the QCL is operating in an injection seeded regime.