External cavity quantum cascade lasers with ultra rapid acousto-optic tuning

We report operation of tunable external cavity quantum cascade lasers with emission wavelength controlled by an acousto-optic modulator (AOM). A long-wave infrared quantum cascade laser wavelength tuned from similar to 8.5 mu m to similar to 9.8 mu m when the AOM frequency was changed from similar to 41 MHz to similar to 49 MHz. The laser delivered over 350 mW of average power at the center of the tuning curve in a linewidth of similar to 4.7 cm(-1). Measured wavelength switching time between any two wavelengths within the tuning range of the QCL was less than 1 mu s. Spectral measurements of infrared absorption features of Freon demonstrated a capability of obtaining complete spectral data in less than 20 mu s. (C) 2015 AIP Publishing LLC.