Studying tunability of some NIR semiconductor lasers by external cavity setup

In this paper, tunability of three near-infrared semiconductor lasers which typically lase at 808 nm, 892 nm and 980 nm is studied. Both Littrow (wavelength dependent beam direction setup) and Littman (wavelength independent beam direction setup) configurations have been used. The wavelength and the power of the output beam of the laser have been measured. In all three cases, Littrow configuration shows a little better tuning range. In both Littrow and Littman configurations the wavelengths near the main wavelength of the laser had more power. The highest achieved power of these lasers in the Littrow setup was more than that of the Littman setup.