Frequency and phase-lock control of a 3 THz quantum cascade laser.
We have locked the frequency of a 3 THz quantum cascade laser (QCL) to that of a far-infrared gas laser with a tunable microwave offset frequency. The locked QCL line shape is essentially Gaussian, with linewidths of 65 and 141 kHz at the -3 and -10 dB levels, respectively. The lock condition can be maintained indefinitely, without requiring temperature or bias current regulation of the QCL other than that provided by the lock error signal. The result demonstrates that a terahertz QCL can be frequency controlled with 1-part-in-10(8) accuracy, which is a factor of 100 better than that needed for a local oscillator in a heterodyne receiver for atmospheric and astronomic spectroscopy.
Betz
A L
AL
Center for Astrophysics and Space Astronomy, UCB 593, University of Colorado, Boulder, Boulder, Colorado 80309, USA. betz@colorado.edu
Boreiko
R T
RT
Williams
B S
BS
Kumar
S
S
Hu
Q
Q
Reno
J L
JL