Grating distributed feedback quantum cascade laser

Abstract

The invention provides a grating distributed feedback quantum cascade laser which comprises a substrate, a lower waveguide layer, a lower optical confinement layer, an active area, an upper optical confinement layer, an equivalent phase-shifting grating and an upper waveguide layer, wherein the lower waveguide layer, the lower optical confinement layer, the active area, the upper optical confinement layer, the equivalent phase-shifting grating and the upper waveguide layer sequentially grow on the substrate. The equivalent phase-shifting grating is arranged on the upper surface of the upper optical confinement layer and comprises a uniform grating, a sampling grating and a pi phase-shifting structure. Compared with a traditional process for manufacturing the uniform grating, the process for manufacturing the equivalent phase-shifting grating is much simpler, and preparation difficulty of the grating distributed feedback quantum cascade laser is greatly reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductor lasers, in particular to a grating distributed feedback quantum cascade laser. Background technique [0002] Single-mode high-power quantum cascade lasers with a wavelength of 4-9 μm have broad application prospects in the fields of atmospheric environment monitoring, medical diagnosis, and high-resolution spectroscopy. The most conventional and effective way to achieve single-mode operation of quantum cascade lasers is to form a distributed feedback structure by introducing a grating process. Generally, quantum cascade lasers can be divided into buried gratings and surface gratings according to the location of grating fabrication. Among them, buried gratings have attracted much attention due to their smaller waveguide losses. [0003] The buried grating is mainly fabricated on the upper optical confinement layer InGaAs in the active area. Since the grating is very close to the active area,...

AI Technical Summary

Problems solved by technology

[0004] Although the grating coupling coefficient can be reduced by controlling the grating duty cycle and grating depth, the grating coupling coefficient is very sensitive to the grating shape, and any small change in the grating shape will cause a large change in the coupling coefficient

Strictly controlling the grating shape is a great challenge to the current process

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