Fabrication of 100nm-period gratings using achromatic holographic lithography

We have fabricated large area, 100nm-period gratings using achromatic holographic lithography. Previously, we reported fabrication of relatively small area gratings with periods of 270nm and 125nm using an achromatic configuration that incorporated feedback to stabilize the fringes during exposure. In the present scheme, the need for a feedback system has been eliminated by physically clamping together the configuration, thereby achieving mechanical stability. Back reflection from the substrate was eliminated using an anti-reflective coating between the resist (PMMA) and the substrate, resulting in grating lines of high contrast. The area of the grating (currently ≈ 1 cm 2) is limited only by the size of the fused silica optical flats that contain the beam splitter and recombiner gratings.