Micromolded structures for integrated optical sensors

摘要

A novel approach for the fabrication of single-mode channel waveguides combined with focusing grating couplers by replication into polymer substrates is proposed and experimentally demonstrated. The concept is based on fabricating a master structure containing tall ridge patterns (about 3 $mu@m high) combined with shallow, focusing grating structures (about 10 nm depth). By a micromolding technique using nickel shims, this pattern is hot embossed into a polymer substrate which is then full-area coated with a high-index dielectric waveguiding film. The focusing grating coupler is directly connected to the channel guide via a width-tapered waveguide section. An incident collimated beam can thus be coupled without the need for additional optics to the stripe waveguide formed by the film deposited on top of the ridge pattern. Results of experiments on stripe waveguides in quartz, focusing grating couplers in polycarbonate and combined channel waveguide and focusing structures in polycarbonate are presented and discussed. The feasibilty of the novel concept has been demonstrated by coupling a collimated free-space laser beam into a ridge waveguide on a replicated sample. The technology should find applications in integrated optical sensors and other low-cost integrated optical devices.