Frequency locking of single-mode 3.5-THz quantum cascade lasers using a gas cell

Authors :: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Kao, Tsung-Yu
Hu, Qing
Ren, Y.
Hovenier, J. N.
Cui, M.
Hayton, D. J.
Gao, J. R.
Klapwijk, T. M.
Shi, S. C.
Reno, J. L.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Kao, Tsung-Yu
Hu, Qing
Ren, Y.
Hovenier, J. N.
Cui, M.
Hayton, D. J.
Gao, J. R.
Klapwijk, T. M.
Shi, S. C.
Reno, J. L.
Source :: MIT web domain
Publication Year :: 2014
Abstract: We report frequency locking of two 3.5-THz third-order distributed feedback (DFB)quantum cascade lasers(QCLs) by using methanol molecular absorption lines, a proportional-integral-derivative controller, and a NbN bolometer. We show that the free-running linewidths of the QCLs are dependent on the electrical and temperature tuning coefficients. For both lasers, the frequency locking induces a similar linewidth reduction factor, whereby the narrowest locked linewidth is below 18 kHz with a Gaussian-like shape. The linewidth reduction factor and the ultimate linewidth correspond to the measured frequency noise power spectral density.<br />United States. National Aeronautics and Space Administration<br />National Science Foundation (U.S.)

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