Extremely-low-threshold and high-temperature operation in a photopumped ZnSe/ZnSSe blue laser

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Abstract
A ZnSe/ZnSSe blue semiconductor laser was demonstrated to show very low threshold by direct photopumping of the ZnSe active layer. The lowest threshold at the excitation wavelength of 445 nm was 10 kW/cm2 at 300 K which is equivalent to the current density of 3.6 kA/cm2. This is the lowest threshold ever reported in II‐VI photopumped lasers and is approaching the theoretically calculated threshold. The characteristic temperature of the threshold, which characterizes the temperature dependence of the threshold in the exponential form, was 124 K up to the measured 400 K and was comparable to III‐V double‐heterostructure lasers. The differential quantum efficiency remained the similar level up to 400 K and its decrease observed at 400 K was within 23% of the efficiency at 300 K.