High peak power quantum cascade lasers monolithically integrated onto silicon with high yield and good near-term reliability

Abstract

High peak power, room-temperature operation in the long wave infrared spectral region is reported for double-channel, ridge waveguide quantum cascade lasers (QCLs) monolithically integrated onto a silicon substrate. The 55-stage laser structure with an AlInAs/InGaAs core and InP cladding was grown by molecular beam epitaxy directly onto an 8-in. diameter germanium-coated silicon substrate template via a III–V alloy metamorphic buffer. Atomic force microscope imaging demonstrated a good quality surface for the full QCL structure grown on silicon, with improved roughness over wider areas compared to the previous work. Fabricated 3 mm × 26 μm lasers operate at room temperature, deliver more than 3 W of peak (6 mW of average) optical power, and show approximately 3% wall plug efficiency and 4.3 kA/cm2 threshold current density with emission wavelength centered at 11.5 μm. The lasers had a high yield with only around 15% max power deviation and no signs of performance degradation were observed over a 10 h burn in period at maximum power. Singled-lobed high quality output beam with M2 = 1.36 was measured for 3 mm × 22 μm devices, demonstrating that it is possible to produce high-brightness quantum cascade lasers on silicon with standard ridge waveguide processing paving the way for low-cost production of integrated mid-infrared platforms.