Free Induction Decay signals stimulated and detected by photomixing
Résumé
This abstract presents a coherent THz spectroscopy experiment consisting in recording the free induction decay of a collection of carbonyde sulfide (OCS) molecules when polarized coherently by a ~0.29 THz incident pulse resonant with the J=24- >23 OCS rotational line. This was accomplished by employing an optical-cavity-enhanced low-temperature-grown GaAs photoconductor, which was pumped by a free running dual-frequency Ti:Sa laser serving as both a THz pulsed emitter and an optoelectronics mixer. The success of this experiment can be attributed to the exceptional performance of our mixer, boasting a record-conversion efficiency of 30 dB, and the sustained long-term spectral purity of 100 kHz provided by the dual-frequency laser, lasting for over 10 seconds.