Study on the dominant mechanisms for the temperature sensitivity ofthreshold current in 1.3-μm InP-based strained-layer quantum-welllasers

We study the basic physical mechanisms determining the temperature dependence of the threshold current (I_th) of InP-based strained-layer (SL) quantum-well (QW) lasers emitting at a wavelength of 1.3 μm. We show that I_th exhibits a different temperature dependence above and below a critical temperature T_c. It is indicated that T_c is the maximum temperature below which the threshold gain exhibits a linear relationship with temperature. We demonstrate that below T_c the Auger recombination current dominates the temperature dependence of I_th. On the other hand, above T_c a significant increase in both the internal loss and radiative recombination current in the separate-confinement-heterostructure region, which is mainly due to electrostatic band-profile deformation, is found to play a major role in determining the temperature sensitivity of I_th. On the basis of the comparison between the theoretical analysis and the experimental results, we conclude that the temperature dependence of the threshold current in 1.3-μm InP-based SL-QW lasers is dominated by different mechanisms above and below T_c