Fabrication of high-aspect-ratio resonance domain diffraction gratings in fused silica

Resonance domain diffraction gratings with local periods near the wavelength may have very high diffraction efficiencies. Unfortunately, they are difficult to fabricate, especially for use with light in visible and shorter wavelengths. We present several methods for fabricating surface relief resonance domain diffraction gratings used in the visible spectral region. We also optimize the relevant fabrication parameters and compare the resulting performance for each method. For the fabrication, we resort to e-beam lithography and reactive ion etching. Characterization is performed with environmental scanning electron microscopy, atomic force microscopy, and optical measurements on representative structures. Nearly 100% Bragg diffraction efficiency can be achieved with transmission resonance domain binary gratings formed in fused silica and having a period of 0.5 μm and a groove depth of 1 μm.