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Authors: Luis Hoffman, A. Subramanian, Philippe Helin, , Bert Du Bois, R. Baets, Pol Van Dorpe, Georges Gielen, Robert Peurs, Dries Bracken
Title: Low Loss CMOS-compatible PECVD Silicon Nitride Waveguides and Grating Couplers for Blue Light Optogenetic Applications
Format: International Journal
Publication date: 8/2016
Journal/Conference/Book: Photonics
Editor/Publisher: IEEE, 
Internal Reference: [N-1907]
Download: Download this Publication (1.2MB) (1.2MB)


This study presents silicon nitride (SixNy) photonic
integrated circuits (PICs) with high performance at a wavelength of 450 nm, and therefore suitable for neuronal stimulation with optogenetics. These PICs consist of straight and bent waveguides, and grating couplers that are fabricated in a CMOS-compatible
plasma enhanced chemical vapor deposition (PECVD) SixNy platform. Their characterization shows propagation losses of 0.96±0.4 dB/cm on average for straight waveguides 1 µm to 5 µm wide, and bend insertion losses as low as 0.2 dB/90◦ for 1 µm
wide waveguides with a radius of 100 µm. Additionally, the grating couplers characterization shows that they can deliver about 10 µW of light in an area of 5×9 µm2 (240 mW/mm2),which is captured from an un-collimated laser diode (70 mW).
Besides delivering sufficient power for optogenetic applications,the gratings have dimensions that are comparable to the size of a neuron, which would allow single cell interaction. These results
demonstrate that, with this SixNy platform, high density and large scale implantable neural devices can be fabricated and readily integrated into existing CMOS-compatible neuro-electronic platforms.

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