Cylindrical concave diffraction grating utilising thin silicon chip

A unique manufacturing method for concave diffraction gratings is proposed. Also, a cylindrical concave diffraction grating was manufactured with a multimode slab waveguide. A silicon plane diffraction grating was bent cylindrically in this method. The efficiency of the concave diffraction grating was 82% at a 1.3 μm wavelength. The efficiency was about the same as that of the plane diffraction grating.