Heterodyne mixing of two far-infrared quantum cascade lasers by use of a point-contact Schottky diode.
We demonstrate heterodyne mixing of two free-running, multimode, 3.3-THz quantum cascade lasers by use of a point-contact Schottky diode. By temperature tuning the emission wavelength of one laser, a difference frequency signal spanning the 2-4-GHz range is obtained, with a signal-to-noise ratio of 30 dB. The frequency of the heterodyne signal is subject to random fluctuations of a few megahertz, principally from instabilities in the temperatures of the devices. From single-shot measurements we derive an instantaneous linewidth for a single Fabry-Perot mode of 20 kHz, corresponding to an integration time of 3.6 ms.
Barbieri
S
S
TeraView, Ltd., Science Park, Cambridge, UK. stefano.barbieri@teraview.com
Alton
J
J
Beere
H E
HE
Linfield
E H
EH
Ritchie
D A
DA
Withington
S
S
Scalari
G
G
Ajili
L
L
Faist
J
J