We report the characteristics of current induced frequency modulation (FM) for two continuous-wave quantum cascade lasers (QCLs) at 9.06 μm. Both the frequency tuning rate and the phase shift between intensity modulation and FM are measured at different modulation frequencies from 10 Hz to 200 kHz. The frequency tuning rate of the QCLs depends on both the modulation frequency and amplitude. The tested QCL has been used to detect ambient water vapor with wavelength modulation spectroscopy for validation with a numerical model.
© 2012 Optical Society of America
Original Manuscript: September 27, 2011
Revised Manuscript: February 6, 2012
Manuscript Accepted: February 6, 2012
Published: April 11, 2012
Lei Tao, Kang Sun, David J. Miller, M. Amir Khan, and Mark A. Zondlo, "Current and frequency modulation characteristics for continuous-wave quantum cascade lasers at 9.06 μm," Opt. Lett. 37, 1358-1360 (2012)