High-efficiency, high-dispersion diffraction gratings based on total internal reflection.

We report a new class of high-dispersion immersed diffraction gratings for which the reflective nature of the diffraction is provided by the phenomenon of total internal reflection (TIR) regardless of grating tooth shape. Thus, the component can be fabricated from a single dielectric material and requires no metallic or dielectric film layers for high reflection diffraction efficiency. With the absence of metallic absorption, diffraction efficiencies of these TIR gratings can reach more than 99% for 15-20-nm spectral bandwidths, making them suitable for many laser-based technologies.