@Article{Rabanus_etal2009,
author="Rabanus, D.
and Graf, U. U.
and Philipp, M.
and Ricken, O.
and Stutzki, J.
and Vowinkel, B.
and Wiedner, M. C.
and Walther, C.
and Fischer, M.
and Faist, J.",
title="Phase locking of a 1.5 terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver",
journal="Optics Express",
year="2009",
volume="17",
number="3",
pages="1159--1168",
optkeywords="QCL heterodyne; 300 uW at 1.5 THz; HEB mixer",
abstract="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.",
optnote="exported from refbase (https://db.rplab.ru/refbase/show.php?record=628), last updated on Tue, 05 Jul 2011 23:40:33 -0500"
}