Spectroscopic applications and frequency locking of THz photomixing with distributed-Bragg-reflector diode lasers in low-temperature-grown GaAs

Pin Chen, Geoffrey A. Blake, M. C. Gaidis, E. R. Brown, K. A. McIntosh, S. Y. Chou, M. I. Nathan, F. Williamson
1997 Applied Physics Letters  
A compact, narrow-linewidth, tunable source of THz radiation has been developed for spectroscopy and other high-resolution applications. Distributed-Bragg-reflector ͑DBR͒ diode lasers at 850 nm are used to pump a low-temperature-grown GaAs photomixer. Resonant optical feedback is employed to stabilize the center frequencies and narrow the linewidths of the DBR lasers. The heterodyne linewidth full-width at half-maximum of two optically locked DBR lasers is 50 kHz on the 20 ms time scale and 2
more » ... z over 10 s; free-running DBR lasers have linewidths of 40 and 90 MHz on such time scales. This instrument has been used to obtain rotational spectra of acetonitrile (CH 3 CN) at 313 GHz. Detection limits of 1ϫ10 Ϫ4 Hz 1/2 ͑noise/total power͒ have been achieved, with the noise floor dominated by the detector's noise equivalent power.
doi:10.1063/1.119845 fatcat:gt7wkef74bc2babfxh2skjnrhy