Wavelength combining laser apparatus

A wavelength combining laser apparatus comprising:

• a semiconductor laser to emit, in a direction of an optical axis, a plurality of laser beams from a light emitting end face of a plurality of light emitting portions aligned in a laser beam combining direction, the direction of the optical axis being perpendicular to the laser beam combining direction;
• a beam shaping element that is provided to face the light emitting end face and is a plurality of lens surfaces with exit surfaces aligned in the laser beam combining direction, the exit surfaces collimating the plurality of laser beams and allowing exit of the plurality of laser beams;
• a wavelength combining element to combine the plurality of laser beams from the exit surfaces in the laser beam combining direction into a single laser beam and output the single laser beam;
• a cross-coupling reduction optical system having a positive power in the laser beam combining direction perpendicular to an optical axis of the single laser beam that is output from the wavelength combining element;
• and
• a partially-reflective mirror to reflect the single laser beam that passes through the cross-coupling reduction optical system and to allow the single laser beam to transmit through and exit the partially-reflective mirror, wherein
• the cross-coupling reduction optical system is disposed to image the exit surfaces on the partially-reflective mirror by causing the exit surfaces to be conjugate to the partially-reflective mirror in a plane formed by the optical axis of the single laser beam and the laser beam combining direction.