Efficient high-order diffraction of extreme-ultraviolet light and soft x-rays by nanostructured volume gratings

We report what is believed to be the first demonstration that volume gratin gs diffract extreme-ultraviolet light (EUV) or soft x-rays into high orders approximately an order of magnitude more efficiently than predicted by cla ssical thin-grating theory. At the 13-nm wavelength, copolymer grating stru ctures with 200-nm period and aspect ratios of similar to 10:1 achieved dif fraction efficiencies of 11.2%, 15.3%, 11.5%, and 9.1% in the orders m of 2 , 3, 4, and 5, respectively. In addition, the measured transmission spectra are consistent with electrodynamic calculations by coupled-wave theory. Hi gh-order diffraction can now be employed for substantially improved diffrac tive EUV and x-ray optics, e.g., highly resolving diffractive lenses and la rge-aperture condensers. (C) 2001 Optical Society of America.