Development and application of a 100 MHz-resolution terahertz time-domain spectrometer

Abstract

We will report on our development and application of a terahertz (THz) time-domain spectrometer employing asynchronous optical sampling (ASOPS) between two com. Ti:Sapphire lasers operating with a repetition rate of approx. 80 MHz, and a THz frequency resoln. approaching the limit of that repetition rate. Time-domain terahertz spectrometers are often based on scanning mech. delay stages; yielding a practically feasible resoln. limit of several GHz. There are com. available THz timedomain spectrometers employing ASOPS with GHz repetition rate lasers; they achieve 1 GHz resoln. The use of our lower repetition rate lasers, while introducing tech. challenges, offers a theor. resoln. limit of approx. 80 MHz. Applications to be presented include the rotational spectrum of water as a demonstration of instrument performance, as well as spectra of pseudorotational modes in THF and long-delay THz emission measurements of coherent spin precession lifetimes of THz-pumped magnons in candidate spintronics materials.