Fabrication of an elastomeric rib waveguide Bragg grating filter

Abstract

We report the design and fabrication of a Bragg grating device on a silicone-based elastomer rib waveguide, constructed using solvent-assisted microcontact molding and polymer casting techniques. The waveguide design utilizes polydimethylsiloxane (PDMS) and hard polydimethylsiloxane (hPDMS) polymers as core and cladding materials, with a period of ~0.55 μm, a depth of ~350 nm, and a grating length of 6 mm. Fabrication is relatively simple, with the hPDMS/PDMS waveguide and gratings cast from a two-layer mold made of a phenolic resin-based positive photoresist and an epoxy Novolak resin-based negative photoresist. The mold we have designed has a demonstrated operational lifespan in excess of ten successful waveguide fabrications. The transmission spectra of the resulting gratings were measured, with test results showing a band-rejection gain of −17 dB and a 3 dB bandwidth of ~3 nm at transmission.