Abstract
In this work, we demonstrate trapping of microparticles using plasmonic tweezers based on arrays of annular apertures. The transmission spectra and the electric-field distribution are simulated to calibrate the arrays. Theoretically, we observe sharp peaks in the transmission spectra for dipole resonance modes and these are red-shifted as the size of the annular aperture is reduced. We also expect an absorption peak at approximately 1115 m for the localised plasmon resonance. Using a laser frequency between the two resonances, multiple plasmonic hot spots are created and used to trap and transport micron and submicron particles. Experimentally, we demonstrate trapping of individual 0.5 μm and 1 μm polystyrene particles and the feasibility of particle transportation over the surface of the annular apertures using less than 1.5 mW μm−2 incident laser intensity at 980 nm.
Highlights
To address the problems associated with conventional optical tweezers for trapping objects in the Rayleigh regime, plasmonic tweezers (PTs) - which can confine the incident laser beam to the nm-scale - have been developed
The transmission of the trapping laser through the array was collected by a condenser (50 X, N.A = 0.55) and measured by an avalanche photodetector (APD) at 1 kHz frequency
The above hypothesis of trap stiffness self-adjustment with lower laser intensity excitation for S2 when compared to S1 and S3 is very similar to previous reports on the self-induced back action (SIBA) effect [13,14]
Summary
To address the problems associated with conventional optical tweezers for trapping objects in the Rayleigh regime, plasmonic tweezers (PTs) - which can confine the incident laser beam to the nm-scale - have been developed. These devices provide an alternative and robust technique for scaling optical trapping down to subwavelength particles [1,2,3,4,5,6]. Polystyrene beads with a minimum diameter of 200 nm have been successfully transported using a nano-optical conveyor belt [17, 18] Another major advantage of PTs is the tunability of the resonance frequency towards the near-infrared (NIR) region. While heating could be helpful, it should, be avoided for most PTs applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
