Lasing of a Quantum-Cascade Laser with a Thin Upper Cladding

Abstract

We present the results of experiments on the fabrication and study of the properties of quantum-cascade lasers of the spectral range of 7–8 μm in the geometry of a waveguide with a thin top cladding based on indium phosphide. The heterostructure is synthesized by molecular beam epitaxy on an InP substrate with an active region based on a heteropair of In_0.53Ga_0.47As/Al_0.48In_0.52As solid alloys. Laser emission at a wavelength of 7.8 μm at a temperature of 300 K with a threshold current density of ~6 kA/cm² was achieved. The values of characteristic temperatures T₀ and T₁ for the studied quantum-cascade lasers are of the order of 150 and 450 K, respectively. The results obtained confirm that the design of the waveguide with a thin top cladding for devices for detecting liquids, the fabrication of microfluidic devices, and photonic circuits on silicon holds promise.