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.
TeraView, Ltd., Science Park, Cambridge, UK. stefano.barbieri@teraview.com
S
S
Barbieri
J
J
Alton
H E
HE
Beere
E H
EH
Linfield
D A
DA
Ritchie
S
S
Withington
G
G
Scalari
L
L
Ajili
J
J
Faist