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Optical Trapping of Plasmonic Nanoparticles for In Situ Surface-Enhanced Raman Spectroscopy Characterizations
Published on: June 23, 2022
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Integrated photonics multi-waveguide devices for optical trapping and Raman spectroscopy: design, fabrication and
Gyllion B Loozen1, Arnica Karuna1,2, Mohammad M R Fanood1
1Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands.
Beilstein Journal of Nanotechnology
|June 20, 2020
Summary
Integrated photonics multi-waveguide devices enable optical trapping and Raman spectroscopy of particles in fluids. These devices create stable trapping regions, allowing for detailed particle analysis free from surface interference.
Area of Science:
- Photonics
- Optical trapping
- Spectroscopy
Background:
- Traditional dual-waveguide traps suffer from light concentration near facets, limiting trapping stability.
- A need exists for robust optical trapping systems capable of simultaneous spectroscopic analysis of microparticles in fluids.
Purpose of the Study:
- To design, fabricate, and demonstrate integrated photonics multi-waveguide devices for particle trapping and Raman spectroscopy.
- To overcome limitations of existing optical traps by creating a stable, surface-free trapping region.
- To characterize the trapping performance and spectroscopic capabilities of these novel devices.
Main Methods:
- Design and simulation of multi-waveguide structures using a silicon nitride (Si3N4) platform.
- Fabrication of ridge waveguides fanned out from a single input using Y-splitters, with a second layer for scattered light detection.
- Microfluidic integration for sample introduction via capillary forces.
- Experimental demonstration using polystyrene beads (1 and 3 μm) in 2- and 16-waveguide devices.
- Analysis of confined Brownian motion to determine trap stiffness and Raman spectroscopy for particle identification.
Main Results:
- Multi-waveguide interference generates an array of 'hot spots' forming stable local traps around the device center.
- Experimental confirmation of trapping and spectroscopic analysis of polystyrene beads.
- Measured trap stiffness values for the 16-waveguide device are comparable to tightly focused Gaussian beam traps.
- Characteristic Raman spectra of polystyrene beads were obtained, with a background attributed to the Si3N4 waveguides.
Conclusions:
- Integrated photonics multi-waveguide devices offer a robust platform for optical trapping and Raman spectroscopy of microparticles.
- The multi-beam interference approach effectively creates stable trapping regions, overcoming surface influence.
- These devices show significant potential for applications in particle analysis, characterization, and manipulation in fluidic environments.
