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

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.

[1]  Florian Merget,et al.  Silicon nitride CMOS-compatible platform for integrated photonics applications at visible wavelengths. , 2013, Optics express.

[2]  Roel Baets,et al.  Efficiency of evanescent excitation and collection of spontaneous Raman scattering near high index contrast channel waveguides. , 2015, Optics express.

[3]  Roel Baets,et al.  Enhancement of light absorption, scattering and emission in high index contrast waveguides , 2013 .

[4]  R. Baets,et al.  Nanophotonic lab-on-a-chip Raman sensors: A sensitivity comparison with confocal Raman microscope , 2015, 2015 International Conference on BioPhotonics (BioPhotonics).

[5]  E. Sleeckx,et al.  Highly efficient grating coupler between optical fiber and silicon photonic circuit , 2009, 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum electronics and Laser Science Conference.

[6]  T. Krauss,et al.  Compact and Highly Efficient Grating Couplers Between Optical Fiber and Nanophotonic Waveguides , 2007, Journal of Lightwave Technology.

[7]  P ? ? ? ? ? ? ? % ? ? ? ? , 1991 .

[8]  R. Baets,et al.  Low-Loss Singlemode PECVD Silicon Nitride Photonic Wire Waveguides for 532–900 nm Wavelength Window Fabricated Within a CMOS Pilot Line , 2013, IEEE Photonics Journal.

[9]  W. Marsden I and J , 2012 .

[10]  S. Selvaraja,et al.  Visible Wavelength Photonic Integrated Circuit in Silicon Nitride Platform for On-Chip Sensing Applications , 2019, 2019 Workshop on Recent Advances in Photonics (WRAP).

[11]  R. Baets,et al.  Compact efficient broadband grating coupler for silicon-on-insulator waveguides. , 2004, Optics letters.

[12]  Derek A. Long,et al.  The Raman Effect: A Unified Treatment of the Theory of Raman Scattering by Molecules , 2001 .

[13]  Roel Baets,et al.  Evanescent excitation and collection of spontaneous Raman spectra using silicon nitride nanophotonic waveguides. , 2014, Optics letters.

[14]  M. Zervas,et al.  Surface and waveguide collection of Raman emission in waveguide-enhanced Raman spectroscopy. , 2016, Optics letters.

[15]  D Vermeulen,et al.  Bridging the gap between nanophotonic waveguide circuits and single mode optical fibers using diffractive grating structures. , 2010, Journal of nanoscience and nanotechnology.

[16]  Young-Kai Chen,et al.  Wide Bandwidth Silicon Nitride Grating Coupler , 2010, IEEE Photonics Technology Letters.

[17]  Microscope-less lab-on-a-chip Raman spectroscopy of cell-membranes , 2016, 2016 IEEE Photonics Conference (IPC).

[18]  A. Driessen,et al.  Raman spectroscopy with an integrated arrayed-waveguide grating. , 2011, Optics letters.

[19]  K. Komorowska,et al.  Near-Infrared Grating Couplers for Silicon Nitride Photonic Wires , 2012, IEEE Photonics Technology Letters.

[20]  Roel Baets,et al.  The role of index contrast in the efficiency of absoprtion and emission of a luminescent particle near a slab waveguide , 2012 .

[21]  Grating couplers for Si3N4 waveguides at 900 nm , 2012 .