The invention discloses a multi-
wavelength laser, a preparation method and the application thereof. The multi-
wavelength laser is at least composed of an encapsulation substrate, a thermoelectric cooler, a base plate, a piece of slide glass and a
laser chip, wherein, the laser
chip at least consists of a
semiconductor substrate, distributed feedback Bragg raster display, a lower cladding, a lower
barrier layer, an active region, an upper
barrier layer, an upper cladding, the distributed feedback Bragg raster display and a
metal electrode in sequence; the active region is internally provided with an active
gain medium which is formed by a plurality of preconcerted
quantum dot belts which are made of
semiconductor dielectric material and have modulatory components and sizes, and each of the
quantum dot belts internally contains a plurality of
quantum dots having the same size and uniform distribution; the quantum dots are arranged in line, each of the
quantum dot belts is corresponding to different lasing wavelengths, and the sizes of the quantum dots in the
quantum dot belts are not the same as each other; the invention is characterized by good
wavelength selectivity, high conversion
quantum efficiency, high light output power, etc.