Grating-coupled external cavity quantum cascade semiconductor lasers

Summary form only given. Widely wavelength-tunable mid-infrared lasers are useful for broadband spectral sensing. Grating-coupled external cavity InAs/InAsSb or GaSb/InAsSb 3-4 /spl mu/m lasers have been demonstrated with large tuning range. The work investigates the wavelength tuning property of InGaAs/InAlAs quantum cascade lasers using grating-coupled external cavity. An objective is to determine the optimal condition for threshold and power efficiency as a function of wavelength and temperature. Knowledge of these conditions can help choosing a wafer design for which a DFB or DBR laser can be fabricated for a specific a wavelength and temperature range. The materials were grown by MBE and fabricated into 10-12 /spl mu/m-wide, 0.5-2 mm-long ridge-waveguide lasers. Typical free-running power was /spl sim/350 mW peak at 80 K and /spl sim/ few 10's mW above 220 K.