External-cavity laser

The invention provides an external-cavity laser and belongs to the technical field of optical devices. The external-cavity laser includes a mirror, a grating, a first coupling mirror, a second coupling mirror, a beam splitter, a laser source, and an output fiber; wherein the laser source, the beam splitter, the first coupling mirror and the second coupling mirror are integrated. The light emittedby the laser source is collimated to the surface of the beam splitter and is split by the beam splitter. The reflected light is collimated to the surface of the grating by the first coupling mirror. Through grating membrane, first order diffracted light is reflected by the mirror and returned to the beam splitter along an original path. A part of the light is reflected again by beam splitter to alaser gain element in the laser source. Another part of the light is finally projected through the beam splitter, is coupled and is then output by the fiber. The other part of the light is coupled andoutput by the second coupl