Laser cavity for Littman structure

The invention provides a laser cavity for a Littman structure. The laser cavity comprises a semiconductor gain chip arranged in the cavity, a coupling mirror and a grating which are fixedly arranged on a base, and a reflector fixed on the base through a compensation unit; the cavity length of the cavity is Ld, the length of the compensation unit is Ls, and the length of the cavity on the base is Lb; when the temperature rises, the base expands, and the Lb is increased; meanwhile, the compensation unit is influenced by the temperature, the length Ls of the compensation unit is also increased, and the change of the length Ld of the cavity is counteracted. According to the technical scheme of the invention, 1, after the compensation unit is installed on the reflector, the compensation of the length of the cavity is realized through the extension and retraction of the compensation unit; and 2, the compensation unit is made of a temperature sensitive material, and extends or retracts along with the change of the t