Frequency and amplitude stabilized terahertz quantum cascade laser as local oscillator

• Main Authors: Ren, Y. (Author), Hayton, D. J. (Author), Hovenier, J. N. (Author), Cui, M. (Author), Gao, J. R. (Author), Klapwijk, T. M. (Author), Shi, S. C. (Author), Kao, Tsung-Yu (Contributor), Hu, Q. (Author), Reno, J. L. (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science (Contributor), Massachusetts Institute of Technology. Research Laboratory of Electronics (Contributor)
• Format: Article
• Language: English
• Published: American Institute of Physics, 2014-05-02T18:51:23Z.
• Subjects: Article
• Online Access: Get fulltext

 We demonstrate an experimental scheme to simultaneously stabilize the frequency and amplitude of a 3.5 THz third-order distributed feedback quantum cascade laser as a local oscillator. The frequency stabilization has been realized using a methanol absorption line, a power detector, and a proportional-integral-derivative (PID) loop. The amplitude stabilization of the incident power has been achieved using a swing-arm voice coil actuator as a fast optical attenuator, using the direct detection output of a superconducting mixer in combination with a 2nd PID loop. Improved Allan variance times of the entire receiver, as well as the heterodyne molecular spectra, are demonstrated.