A Pb0.97Cd0.03S0.9Se0.1diode laser with pulsed operation at up to a temperature of 162 K and a PbS0.53Se0.47 diode laser with CW operation at 28 K have been fabricated by a horizontal unseeded vapor growth technique, self diffusion and mesa stripe-geometry. Their emission wavelengths are 3.22 μm and 5.53 μm respectively. In pulsed operation and CW operation the threshold current density are as low as 143 A/cm2 and 41 A/cm2 at 12 K respectivety.