The effects of biaxial strain produced by the lattice mismatch of constituent materials on
the optical properties of strained In1−xGaxAsyP1−y/In1−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., k→⋅p→ 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.
