Device characteristics and metal-dielectric high reflectivity coating analysis of λ ∼ 1.3 μm InGaAsP/InGaAsP MQW PBH lasers

The cavity length-dependent characteristics of compressively strained InGaAsP/InGaAsP multiple quantum well planar buried heterostructure lasers operating; at lambda similar to 1.3 mu m were investigated under continuous-wave mode. The uncoated 600 mu m tong laser exhibits P-max = 33.6 mW and I-th = 12.9 mA at 25 degrees C with d lambda/dT = 0.35 nm/K and d lambda/dP(e) = 0.044 nm/mW, leading to stable beam characteristics of 19.7 degrees (parallel) x 24.1 degrees (perpendicular). From the inverse slope efficiency versus cavity length plot, the loss parameters of internal differential efficiency (eta(i)) and internal optical loss (alpha(i)) were extracted, i.e., eta(i) = 78% and alpha(i) = 10.6 cm(-1). The transparent current density of J(tr) = 0. 12 kA/cm(2) and modal gain of G = 49.5 cm(-1) were also estimated from cavity length-dependent threshold current density measurements. Metal-dielectric Au/Ti/SiO2 layers for high reflectivity (HR) coating were analyzed using theoretical calculations and experimental results. For the HR-coated 600 mu m long laser with Au (150 nm)/Ti (5 nm)/SiO2 (250 nm), P-max increased up to 61 mW at 25 degrees C with a reduced I-th of 10.6 mA compared to the uncoated laser, providing an HR of about 94%. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim