Gain and Threshold Improvements of 1300 nm Lasers Based on InGaAs/InAlGaAs Superlattice Active Regions

A detailed experimental analysis of the impact of active region design on the performance of 1300 nm lasers based on InGaAs/InAlGaAs superlattices is presented. Three different types of superlattice active regions and waveguide layer compositions were grown. Using a superlattice allows to downshift the energy position of the miniband, as compared to thin InGaAs quantum wells, having the same composition, being beneficial for high-temperature operation. Very low internal loss (~6 cm−1), low transparency current density of ~500 A/cm2, together with 46 cm−1 modal gain and 53 % internal efficiency were observed for broad-area lasers with an active region based on a highly strained In0.74Ga0.26As/In0.53Al0.25Ga0.22As superlattice. Characteristic temperatures <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{0}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{1}$ </tex-math></inline-formula> were improved up to 76 K and 100 K, respectively. These data suggest that such superlattices have also the potential to much improve VCSEL properties at this wavelength.