Liquid-phase epitaxy grown PbSnTe distributed feedback laser diodes with broad continuous single-mode tuning range

Distributed feedback (DFB) pulsed laser operation has been demonstrated 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 780cm^-1(12.8 μm) and was fabricated prior to the liquid-phase epitaxial growth using holographic exposure techniques. These DFB lasers had moderate thresholds, 3.6 kA/cm², and the output power versus current curves exhibited a sharp turn-on free of kinks. Clean, single-mode emission spectra, continuously tunable over a range in excess of 20 cm^-1, centered about 780 cm^-1(12.8 μm), and at an average rate of 1.2 cm^-1. K^-1from 9 to 26 K, were observed. While weaker modes could 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.