Pb1-xSnxSe/PbSe heterostructure lasers

CW operation has been readily achieved in Pb_1-xSn_xSe diode lasers fabricated by hot-wall epitaxy using broad area or striped geometry. Single heterostructure lasers were produced by growing bismuth-doped (50 p.p.m.) PbSe epitaxial layers on Pb_1-xSn_xSe substrates which had dislocation densities of ~(5 - 10) × 104 cm₂. These laser devices operated CW at temperatures up to 72 K with an overall tuning range of 217 cm_-1. The pulse threshold current density was 54 A cm_-2 at 5 K and 550 A cm_-2 at 77 K. These values are lower than the values reported at these temperatures for the best double heterostructure Pb_1-xSn_xSe lasers. This good performance in single heterostructure Pb_1-xSn_xSelasers was achieved primarily due to an improved method of substrate preparation using a new electrolytic polishing procedure developed at the University of Hull. Further improvements could be anticipated of a double heterostructure device configuration.