Apparatus for spectrally combining broadband laser beams by volume Bragg gratings

A spectral beam combiner comprising;

• at least one pair of a first transmitting volume Bragg grating (TVBG) and a second TVBG spaced apart along a light path, the first TVBG being aligned at one of “+” and “−” Brsgg angles, and the second TVBG being aligned a her one of the “30 ” and “−” Bragg angles, which is opposite to the one Bragg angle, wherein the first TVBG and the second TVBC provide sequential diffraction of a first roadband beam which is incident on the first TVBG at a first central wavelength satisfying the Bragg condition,
• the first TVBG and the second TVBG being configured identically to one another so that dispersions of the first TVBG and the second TVBG, respectively compensat one anothe to eliminate gence of the sequentially diffracted first broadband beam in a plane of diffraction, and
• the second TVBO transmitting a second broadband beam at a second central wavelength which does not satisfy the Bragg condition, the second beam being launched her th opposite Bragg angle, so that the sequentially diffracted first broadband beam and the transmitted second broadband beam merge into a single high-power collimated broadband output beam.