Nanotech – Research

Details Created: 13 December 2013

[This Nanotech West Lab Research News article was contributed by the group of Prof. Ron Reano, Associate Professor of Electrical and Computer Engineering, and ElectroScience Laboratory, of The Ohio State University]

Silicon photonics is a promising approach for chip-scale integrated optics. A single-mode silicon strip waveguide designed for operation in the infrared, for example, has a typical submicron cross-section of 450 nm x 250 nm. Highly confined optical modes allow for high density integration and waveguide bends with micrometer scale radii of curvature. The high confinement, however, also produces major challenges when attempting to efficiently couple light between silicon strip waveguides and optical fibers. Mode conversion from a single-mode fiber, with mode field diameter equal to 10 micrometers, results in a coupling loss that is greater than 20 dB. Current methods designed to achieve efficient fiber-to-chip coupling generally involve edge coupling using inverse width tapered waveguides or surface coupling using grating couplers. Inverse width tapers enable low loss and broadband edge coupling but require dicing or cleaving the chip. Alternatively, grating couplers enable light coupling via the surface of the chip without the need for cleaving. They require, however, a tradeoff between bandwidth and efficiency.

Read more: Cantilever Couplers for Low-loss Fiber Coupling to Silicon Photonic Integrated Circuits

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Nanotech - Research