2 μm~5 μm mid-infrared vertical cavity surface emitting laser (VCSEL), featured with advantages of low power con-sumption, small divergence angle, no astigmatism circular spot, high modulation bandwidth, wavelength stability, low production cost, and high density ultra-small dimensional packaging, is an ideal light source for the molecular spectrum measurement, biochemical testing, laser radar, thermal imaging and medical diagnosis. For example, in the TDLAS (tunable laser diode absorption spectroscopy test) system for monitoring polluting gases CO, CH₄, NH₃and HF, the use of VCSEL as a light source will greatly reduce the complexity and the cost for no beam shaping and easily coupled packaging, and shrink the size of the system. Furthermore, its modulation rate can reach several tens of Gbit/s, so it is considered to be the best alternative device of distributed feedback (DFB) laser in the future. As the GaSb material can cover the entire mid-infrared band, it is the best material system for the development of 2 μm~5 μm mid-infrared VCSEL.