Biaxial Strain Effects on Optical Characteristics of Quantum Well Lasers

Abstract

The effects of biaxial strain produced by the lattice mismatch of constituent materials on the optical properties of strained In_xGaxAsyt'l _y/In] _xGaxAs quantum well lasers are investigated.The optical gain and refractive index change of a biaxially stressed quantum well lasers are studied theoretically using the multiband effective mass equation (i.e., :. t7 method), deformation potential theory and Fermi-Golden rule, band mixing effect is retained in the calculations. It is found that the biaxial strain would change the subband structures and optical properties of quantum well lasers, we found the gain of TE mode increases with increasing compressive strain, while the gain of TM mode increases with increasing tensile strain, these will be benefited for reducing the threshold current depending on whether the quantum well lasers are operating in TE or TM mode. On the other hand, the refractive index change in the active region near the TE(TM) mode peak gain becomes more negative when a biaxial compressive(tensile) strain is applied, it leads to the conclusion that the strain weakens the optical confinement, the temperature dependence of gain also becomes stronger when there is strain. Finally, we also found the minimum peak gain occurs when a small tensile strain is applied, but no strain.