Dominant mechanism for limiting the maximum operating temperature of InP-based multiple-quantum-well lasers

Abstract

We study the basic mechanism for limiting the maximum operating temperature (T_m) of InP‐based multiple‐quantum‐well (MQW) lasers emitting at a wavelength of 1.3 μm. It is shown that laser operation is characterized in terms of the temperature dependence of threshold gain (g_th) by introducing a critical temperature (T_c): g_th exhibits a linear relationship with temperature below T_c, while it superlinearly increases with increasing temperature above T_c. This rapid increase in g_th leads to a marked increase in threshold current and a significant reduction in differential quantum efficiency above T_c. We indicate that T_c exhibits a direct correlation with T_m: the higher T_c, the higher T_m. In the temperature range above T_c, laser operation moves into a loss‐multiplication regime, where a considerable portion of the injected carriers brings about a significant increase in internal loss rather than gain due to their pileup in the separate confinement heterostructure layers. We demonstrate that an anomalous increase in internal loss, which occurs at the final stage in this loss‐multiplication regime, determines T_m of 1.3 μm InP‐based MQW lasers.