Reduction of the threshold current of InGaAsP/lnP heterolasers by unidirectional compression

A study was made of the influence of unidirectional compression along the normal to the active plane of injection lasers emitting in the wavelength range 1.06–1.60μ. In the case of the mode with the TM polarization an increase in the uniaxial pressure reduced the threshold current (by 10–30%), increased the differential efficiency, enhanced the parameter T₀ of the temperature dependence of the threshold current, and lowered the point T_b corresponding to a kink in this dependence. In the case of the TE polarization all these effects were opposite. Since the initial stressed state of the investigated laser heterostructures did vary, three different types of sample were distinguished: 1) those exhibiting switching from the TE to TM polarization under the influence of pressure; 2), 3) those operating in the TE polarization or TM polarization in the investigated range of pressures (up to 2.5 kbar). The initial elastic deformation because of some mismatch between the crystal lattices at the heterojunction were the cause of the scatter of the laser parameters. It would be desirable to optimize the mismatch between the lattices because in the case of complete matching the value of T₀ was lowest.