LPE-Grown PbSnTe distributed feedback laser diodes with broad continuous tuning range in single mode output

Distributed feedback operation has been demonstrated under pulsed conditions in stripe geometry. Pb1-xSnxTe double heterostructures grown by liquid phase epitaxy. The grating structure of 0.79 µm periodicity operates in first order near 780 cm^-1(12.8 µm); it was fabricated prior to the liquid phase epitaxy growth. These DFB lasers had moderate thresholds, 3.6 kA/cm², and the output power-versus-current curves exhibited sharp turn on and were free of kinks. Unusually clean, single-mode emission spectra, continuously tunable over a range in excess of 20 cm^-1centered about 780 cm^-1(12.8 µm) at an average rate of 1.2 cm^-1/K from 9K to 26K, were observed. While weaker modes can at times be seen in the spectrum, substantially single mode operation was obtained over the entire operating range and to over 10 times threshold. These observations have been shown to be in good agreement with published lead-salt parameter values and DFB theory, and significantly increase the attractiveness of the DFB structure for tunable lead-salt laser diodes.