Patent ID: 8340143

Claim:
A passive mode-locked picosecond laser device, wherein it comprises a pump source, a laser crystal, a laser cavity and a mode-locked output structure, wherein the pump source is provided at the incident end surface of the laser crystal, for pumping the laser crystal; the laser cavity comprises a plane reflective mirror and a first plano-concave mirror wherein the plane reflective mirror is placed opposite to the concave surface of the first plano-concave mirror and located on the position of the focal radius of the first plano-concave mirror, and the normal direction of the plane reflective mirror and the axis of the first plano-concave mirror form a small angel therebetween; and the laser light emitted by the laser crystal oscillates in the laser cavity and is mode-locked output through the mode-locked output structure, wherein the laser crystal is embedded in the first plano-concave mirror, and wherein the angle between the normal direction of the plane reflective mirror and the axis of the first plano-concave mirror is θ, where 0°<θ<1°, wherein the mode-locked output structure comprises a second plano-concave mirror, a semiconductor saturable absorber, a polarizer, a ¼ wave plate and a 45° reflective mirror wherein the polarizer receives the laser light from the laser crystal, and reflects it to the second plano-concave mirror through the ¼ wave plate; the second plano-concave mirror is used for receiving the laser light reflected by the polarizer, and reflecting the laser light which is then made to be perpendicularly incident on the semiconductor saturable absorber, the 45° reflective mirror receives the laser light which is reflected back from the semiconductor saturable absorber and output from the polarizer through the second plano-concave mirror and the ¼ wave plate, and reflects the laser light as the output.