The influence of tensile strain on differential gain and Auger recombination in 1.5-μm multiple-quantum-well lasers

A systematic study has been undertaken including growth, characterization, and modeling of tensile-strained multiple-quantum-well (MQW) lasers with emission wavelengths in the neighborhood of 1.5 μm. The laser threshold increases between 0% and -0.5% mismatch, switching from TE to TM polarized emission at -0.5%, then decreases to -1.3 % mismatch, with TM polarized emission. The threshold current density has a much weaker dependence on inverse cavity length in the highly tensile-strained lasers than has previously been observed for lattice-matched and compressive lasers emitting in the same wavelength range. We present theoretical calculations which show that the observed differences are well explained, both qualitatively and quantitatively, by the calculated variation with strain of the optical confinement factor Γ and the differential gain at transparency, dg/dn (n_tr). More detailed comparison with experiment suggests that Auger recombination provides the dominant contribution to the threshold current density. Estimated Auger coefficients C are in good agreement with those previously obtained using other techniques