Fabrication method of a diffractive optic for hybrid coherent and spectral beam combination

An integrated optical device that includes a diffractive optical element for combining coherent beams having different angular displacements and a spectral beam combiner for combining incoherent beams having different wavelengths and angular displacements, said device comprising:

• a planar substrate having a surface and a thickness;
• and
• a periodic structure formed into the surface of the substrate in a first direction substantially orthogonal to the thickness of the substrate that defines the diffractive optical element and a periodic grating having channels formed into the surface of the substrate in a second direction substantially orthogonal to the first direction and the thickness of the substrate that defines the spectral beam combiner so that the surface of the substrate is flat, wherein the periodic structure includes periodic modulations along the length of the channels that are orthogonal to a channel-to-channel periodicity of the periodic grating.