Abstract

For the majority of packaging schemes in silicon photonics, out-of-plane optical access to the waveguide layer is achieved via the chip frontside, away from the substrate. As such, fiber grating couplers have generally been optimized with this in mind. In this article, we present two strategies for designing a fiber grating coupler for coupling to optical fibers placed on the backside of the chip, without the need of superposed reflective layers. An all silicon O-band grating coupler is designed, fabricated, and measured with a peak coupling efficiency to a single mode fiber placed on the backside of the chip of −2.8 dB and a −1 dB bandwidth of ∼40 nm. In a second approach, a hybrid silicon nitride/silicon O-band grating coupler is measured in the same configuration with a peak coupling efficiency of −3.2 dB and a −1 dB bandwidth of ∼60 nm.

On-chip unidirectional dual-band fiber-chip grating coupler in silicon nitride

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OSA Continuum 1(3) 864-871 (2018)

Experimental demonstration of an apodized-imaging chip-fiber grating coupler for Si₃N₄ waveguides

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Monolithic integration of microlenses on the backside of a silicon photonics chip for expanded beam coupling

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Single-etch subwavelength engineered fiber-chip grating couplers for 1.3 µm datacom wavelength band

Daniel Benedikovic, Carlos Alonso-Ramos, Pavel Cheben, Jens H. Schmid, Shurui Wang, Robert Halir, Alejandro Ortega-Moñux, Dan-Xia Xu, Laurent Vivien, Jean Lapointe, Siegfried Janz, and Milan Dado
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High-efficiency fiber-to-chip grating couplers realized using an advanced CMOS-compatible Silicon-On-Insulator platform

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Opt. Express 18(17) 18278-18283 (2010)