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Silicon nitride waveguide platform for on-chip spectroscopy at visible and NIR wavelengths

Gali, S and Raghunathan, V and Selvaraja, SK (2020) Silicon nitride waveguide platform for on-chip spectroscopy at visible and NIR wavelengths. In: Integrated Optics: Devices, Materials, and Technologies XXIV 2020, 3-6 February 2020, San Francisco.

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Official URL: https://doi.org/10.1117/12.2545808


On-chip spectroscopy in visible and near-infrared wavelength offers immense potential for various screening and diagnostic application. Silicon Nitride (SiN) is a promising material to realize on-chip spectroscopy as it is transparent over a broad wavelength spectrum; visible-to-mid-infrared. Besides, it is compatible with the CMOS process technology. Since SiN can be deposited using various deposition techniques, it is essential that an appropriate deposition process is chosen to achieve desired properties. We present a detailed study of SiN films deposited using PECVD and LPCVD process. The films were characterized for various, material and optical properties. We also performed waveguide transmission measurement on different SiN films and found a strong correlation with material properties such as stress and autofluorescence to achieve low-loss waveguide. Using the optimized material, we design, fabricate, and demonstrate single-mode SiN wire, spiral waveguides and grating fiber-chip coupler at visible (λ =520nm) and near infra-red (λ = 780nm) wavelengths used for spectroscopy. Furthermore, we use a waveguide to efficiently excite fluorescence or Raman active molecules drop casted as the top cladding of the waveguides. A fraction of the isotopically emitted fluorescence or Raman signal couples back to waveguide and rest is emitted normal to the surface. We discuss the theoretical efficiencies of both the methods of collection and compare it with the conventional microscope-based spectroscopic system. Waveguide based spectroscopic sensing offers higher efficiency due to increased light-matter interaction along the length of the waveguide. We presented detailed design, simulation, and experimental demonstration of grating coupler waveguide system suitable for son-chip spectroscopy application. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

Item Type: Conference Paper
Publication: Proceedings of SPIE - The International Society for Optical Engineering
Publisher: SPIE
Additional Information: Copyright of this article belongs to SPIE
Keywords: Deposition; Efficiency; Fluorescence; Infrared devices; Integrated optics; Nitrides; Optical properties; Raman spectroscopy; Silicon nitride, CMOS process technology; Diagnostic applications; Experimental demonstrations; Light-matter interactions; Silicon nitride waveguides; Spectroscopy applications; Visible and near infrared; Waveguide transmission, Waveguides
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 31 Mar 2021 09:49
Last Modified: 31 Mar 2021 09:49
URI: http://eprints.iisc.ac.in/id/eprint/65309

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