Large-area nanoperforated SiN membranes for optical and mechanical filtering

Nanoperforated membranes can transmit light and modify either the spectral or the spatial properties of the beam passing through the membrane. Alternatively, the perforated membrane can be used as a precisely fabricated filter for nanoparticles, fluids or gases. We made membranes made on a silicon nitride layer deposited on silicon wafer with nanopatterning was realized by nanoimprint lithography. We present two components based on these nanopatterned membranes. Firstly, we demonstrate large-area nanoperforated membranes. The perforations through a 1500 nm thick free-standing silicon nitride (SiN) film have a diameter of 350 nm and a period of 700 nm. The area of the largest free-standing films was 25 mm(2). Secondly, we demonstrate small area membranous optical elements and a method to couple them to optical fibers. Our component uses an optical element processed on the SiN-membrane on silicon wafer. Light is launched and collected through the fiber glued in the trough-wafer via. This component demonstrates a novel and simple way to couple mass producible optical elements with optical fibers. Finally, we fabricate an optical filter utilizing guided-mode resonance on the SiN-membrane. The filter utilizes fiber coupling, and we demonstrate its use as a refractive index sensor. (C) 2009 Elsevier B.V. All rights reserved.