Semiconductor laser apparatus having collimator lens and path rotator

A semiconductor laser apparatus comprising:

• a semiconductor laser array stack in which a plurality of semiconductor laser arrays, each semiconductor laser array having a plurality of active layers each of which extends along a first direction on a predetermined plane and which are arranged along a second direction perpendicular to the first direction and in parallel on the predetermined plane, are stacked in a third direction perpendicular to the predetermined plane;
• a first collimator lens for collimating a plurality of beams emitted from said respective active layers, in the third direction perpendicular to the predetermined plane;
• a path rotator for outputting each beam arriving from said first collimator lens and collimated in the third direction, with a predetermined divergence angle in the third direction in a state in which a transverse section of the beam is rotated by about 90°;
• and
• an optical element arranged at a position where said optical element crosses at least a part of each beam with the predetermined divergence angle in the third direction, outputted from said path rotator, and transmits the rest of the beam, and having a reflecting surface constituting at least a part of an external resonator in cooperation with said active layers,
• wherein the reflecting surface is so inclined at a predetermined angle relative to a plane perpendicular to an optical axis of each beam outputted from said path rotator, as to totally reflect a part of each arriving beam to return the totally reflected part of each beam to the associated one of said active layers,
• wherein an angle of installation of the reflecting surface in said optical element is smaller than a half of the divergence angle of each beam outputted from said path rotator.