Spectrally combined fiber laser amplifier system including optically monolithic beam shaper array with compact tiles

A spectral beam combining (SBC) fiber laser amplifier system comprising:

• a plurality of seed beam sources each generating a continuous wave frequency-modulated seed beam having a central wavelength and a round Gaussian profile, where the wavelength of all of the seed beams is different;
• a plurality of fiber amplifiers each receiving one of the seed beams, each amplifier amplifying the seed beam and placing the amplified beam on a fiber;
• a beam shaper array assembly including an endcap having an input face to which all of the fibers are optically coupled, said assembly further including an input beam shaper array having a plurality of rectilinear input array cells positioned adjacent to and in contact with each other in a tiled manner and arranged as a one-dimensional cell array, each input array cell including an input beam shaper that receives one of the amplified beams and is shaped to cause the beam to expand along a combining dispersive axis as it propagates away from the input beam shaper array to be converted from the round Gaussian profile to a rectilinear shaped beam having flat-top profile and cause the flat-top profile to taper to a lower value at a perimeter of each input array cell, said assembly further including an output beam shaper array including a plurality of rectilinear output array cells positioned adjacent to and in contact with each other in a tiled manner and arranged as a one-dimensional cell array so that each output array cell is matched to an input array cell, each output array cell including an output beam shaper that receives one of the converted beams and is shaped to flatten the wavefront of the converted beam so that the output beam shaper array provides an SBC beam including a plurality of adjacent beams having different wavelengths with minimal overlap and a minimal gap between the beams;
• collimating optics that receives the SBC beam and collimates the adjacent beams;
• and
• an SBC grating that receives the collimated SBC beam from the collimating optics, said grating spatially diffracting the individual beam wavelengths and directing the beams in the same direction as a combined output beam.

A spectral beam combining (SBC) fiber laser amplifier system comprising:

• a plurality of seed beam sources each generating a seed beam having a central wavelength and a low fill factor profile, where the wavelength of all of the seed beams is different;
• a plurality of fiber amplifiers each receiving one of the seed beams, each amplifier amplifying the seed beam and placing the amplified beam on a fiber;
• a beam shaper array assembly including an endcap having an input face to which all of the fibers are optically coupled, said assembly further including an input beam shaper array having a plurality of input array cells positioned adjacent to and in contact with each other in a tiled manner, each input array cell including an input beam shaper that receives one of the amplified beams and is shaped to cause the beam to expand along a combining dispersive axis as it propagates away from the input beam shaper array to be converted from the low fill factor profile to a high fill factor profile and cause the high fill factor profile to taper to a lower value at a perimeter of each input array cell than is possible for an equivalent fill factor Gaussian beam, said assembly further including an output beam shaper array having a plurality of output array cells positioned adjacent to and in contact with each other in a tiled manner so that each output array cell is matched to an input array cell, each output array cell including an output beam shaper that receives one of the converted beams and is shaped to flatten the wavefront of the converted beam so that the output beam shaper array provides an SBC beam including a plurality of adjacent beams having different wavelengths with minimal overlap and a minimal gap between the beams;
• collimating optics that receives the SBC beam and collimates the adjacent beams;
• and
• an SBC grating that receives the collimated SBC beam from the collimating optics, said grating spatially diffracting the individual beam wavelengths and directing the beams in the same direction as a combined output beam.

A method for providing spectral beam combining (SBC), said method comprising:

• generating a plurality of continuous wave frequency-modulated seed beams each having a central wavelength and a low fill factor profile, where the wavelength of all of the seed beams is different;
• amplifying the seed beams;
• causing the amplified beams to expand along a combining dispersive axis as they propagate so as to be converted from the low fill factor profile to a high fill factor profile where the high fill factor profile tapers to a lower value at a perimeter of each beam than is possible for an equivalent fill factor Gaussian beam;
• causing a wavefront of the converted beams to flatten to provide a plurality of adjacent SBC beams having different wavelengths with minimal overlap and a minimal gap between the beams;
• collimating the SBC beams;
• and
• directing the collimated SBC beams onto an SBC grating that spatially diffracts the individual beam wavelengths and directing the beams in the same direction as a combined output beam.