Quantum-level cascaded laser with vertical cavity surface emission function

Abstract

The invention discloses a quantum-level cascaded laser with a vertical cavity surface emission function. The quantum-level cascaded laser comprises a quantum dot active area layer, a distribution Bragg reflector layer and a grating layer, wherein the quantum dot active area layer is formed by inserting a quantum dot insertion layer in each period of an active area of the laser; and the distribution Bragg reflector layer is combined with the grating layer to form a vertical resonant cavity so as to realize surface emission. According to the laser, quantum dot insertion layers are introduced atproper positions in the active area layer, and a quantum dot state serves as a final state of electronic radiative transition, so that a radiation mode of the device has an electric field component vertical to a quantum well plane and then a traditional vertical cavity surface emission laser can be prepared. The laser is capable of improving the power and conversion efficiency of the device and reducing the threshold current on one hand, and is capable of remarkably reducing the size of the device and decreasing the threshold current on the other hand.

Description

technical field [0001] The invention relates to the technical field of infrared semiconductor optoelectronic devices, in particular to a vertical cavity surface emitting quantum cascade laser structure. Background technique [0002] Compared with ordinary semiconductor lasers with inter-band recombination light emission mechanism, quantum cascade lasers are based on sub-band transitions, so they have the advantages of adjustable energy bands and wide wavelength coverage; in gas detection, medical diagnosis, high-resolution It has very broad application prospects in fields such as spectroscopy, but its biggest defect is high threshold power consumption and low power conversion efficiency. However, in some portable applications, quantum cascade lasers are often required to have small volume and low power consumption to facilitate system miniaturization and integration. At present, the ways to obtain low-power quantum cascade lasers mainly include: appropriately reducing the d...

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Problems solved by technology

However, in order to achieve lasing, the surface emitting device must overcome the additional loss caused by the first-order scattering of the second-level grating, which is not conducive to reducing the threshold current density of the device.

At the same time, for a shorter vertical cavity structure, a cavity surface reflectivity as high as 99% is required, usually relying on a multi-layer DBR structure, and more DBR layers will make the device have higher resistance and greater light absorption, affecting the device performance

In addition, the DBR layer matching the InP substrate has InGaAlAs / InAlAs pairs. Since the refractive index difference between the two materials is small, 40-50 pairs need to be grown in order to achieve a reflectivity of more than 99%. On the one hand, the growth rate of the material is increased. On the other hand, such a thick thickness is not conducive to heat dissipation of the device, so the material selection of the DBR layer is also open to question

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