Quantum cascade laser element, quantum cascade laser device, and method for manufacturing quantum cascade laser device

Abstract

A quantum cascade laser element includes: a semiconductor substrate; a semiconductor laminate having a first end surface and a second end surface; a first electrode; a second electrode; and an anti-reflection film formed on the first end surface. The semiconductor laminate is configured to oscillate laser light having a center wavelength of 7.5 μm or more. The anti-reflection film includes an insulating film being a CeOfilm formed on the first end surface, a first refractive index film being a YFfilm or a CeFfilm disposed on a side opposite the first end surface with respect to the insulating film, and a second refractive index film formed on the first refractive index film on a side opposite the first end surface with respect to the first refractive index film and having a refractive index of larger than 1.8.