TY  - JOUR
AU  - Rabanus, D.
AU  - Graf, U. U.
AU  - Philipp, M.
AU  - Ricken, O.
AU  - Stutzki, J.
AU  - Vowinkel, B.
AU  - Wiedner, M. C.
AU  - Walther, C.
AU  - Fischer, M.
AU  - Faist, J.
PY  - 2009
DA  - 2009//
TI  - Phase locking of a 1.5 terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver
JO  - Optics Express
SP  - 1159
EP  - 1168
VL  - 17
IS  - 3
KW  - QCL heterodyne
KW  - 300 uW at 1.5 THz
KW  - HEB mixer
AB  - We demonstrate for the first time the closure of an electronic phase lock loop for a continuous–wave quantum cascade laser (QCL) at 1.5 THz. The QCL is operated in a closed cycle cryo cooler. We achieved a frequency stability of better than 100 Hz, limited by the resolution bandwidth of the spectrum analyser. The PLL electronics make use of the intermediate frequency (IF) obtained from a hot electron bolometer (HEB) which is downconverted to a PLL IF of 125 MHz. The coarse selection of the longitudinal mode and the fine tuning is achieved via the bias voltage of the QCL. Within a QCL cavity mode, the free-running QCL shows frequency fluctuations of about 5 MHz, which the PLL circuit is able to control via the Stark–shift of the QCL gain material. Temperature dependent tuning is shown to be nonlinear, and of the order of -16 MHz/K. Additionally we have used the QCL as local oscillator (LO) to pump an HEB and perform, again for the first time at 1.5 THz, a heterodyne experiment, and obtain a receiver noise temperature of 1741 K.
N1  - exported from refbase (https://db.rplab.ru/refbase/show.php?record=628), last updated on Tue, 05 Jul 2011 23:40:33 -0500
ID  - Rabanus_etal2009
ER  -