Impact of temperature on the linewidth enhancement factor of chirped InAs/InP broadband quantum-dash lasers around 1610 nm

We report on the effect of temperature on the differential gain, differential refractive index, and linewidth enhancement factor (α-factor) of ∼1610-nm chirped barrier thickness multistack InAs quantum-dash (Qdash)-in-a-well laser diodes with an extended active region inhomogeneity. By employing Hakki–Paoli method, the performance is found to be comparable at a lower temperature region (16°C to 25°C), exhibiting higher differential gain and lower α-factor values of ∼0.7  ±  0.1  cm  −  1 mA  −  1 and ∼2.6  ±  1.0, respectively, at gain maximum. At higher temperatures of 25°C to 35°C, the performance degrades mainly due to drop of the differential gain at a rate of ∼0.03  cm  −  1 mA  −  1  °  C  −  1 and α-factor values reaching ∼4.7  ±  2.0 at 40°C. The room temperature (20°C) measured values are in good agreement with the literature, and we qualitatively explain the temperature influence on these results from the highly inhomogeneous Qdash system viewpoint. This study will assist in further optimization of these nanostructure-based high active region gain laser devices that are promising candidates in L-band optical communications, capable of providing low-frequency chirp and high-performance operation.