%0 Journal Article
%T Phase locking of a 1.5 terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver
%A Rabanus, D.
%A Graf, U. U.
%A Philipp, M.
%A Ricken, O.
%A Stutzki, J.
%A Vowinkel, B.
%A Wiedner, M. C.
%A Walther, C.
%A Fischer, M.
%A Faist, J.
%J Optics Express
%D 2009
%V 17
%N 3
%F Rabanus_etal2009
%O exported from refbase (https://db.rplab.ru/refbase/show.php?record=628), last updated on Tue, 05 Jul 2011 23:40:33 -0500
%X 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.
%K QCL heterodyne
%K 300 uW at 1.5 THz
%K HEB mixer
%P 1159-1168