Highly tunable plasmonic nanoring arrays for nanoparticle manipulation and detection

Area of Science:

• Plasmonics
• Nanophotonics
• Optical trapping

Background:

• Advancements in trapping and detecting nano-objects at low laser powers in the near-infrared (NIR) are critical for various applications.
• Singular visible-light nano-optics leveraging abrupt phase changes have shown promise for enhanced molecule detection.

Purpose of the Study:

• To propose and demonstrate tunable plasmonic nanodevices for improved trapping field enhancement and nano-object detection in the NIR.
• To utilize singular phase drops for enhanced optical manipulation.

Main Methods:

• Fabrication of plasmonic nanostructures with 50 nm x 50 nm gaps connecting nanorings in arrays.
• Characterization of tunable properties via extinction and reflection spectra.
• Experimental demonstration of trapping 100 nm polystyrene beads at low incident power.

Main Results:

• The nanodevices exhibit tunable properties with varying aperture sizes.
• A rapid phase change occurs in the topologically-protected, near-zero reflection region.
• Detection sensitivity is predicted to improve by 10 times compared to extinction spectra methods.

Conclusions:

• The plasmonic nanodevices offer enhanced trapping and detection capabilities for nano-objects in the NIR.
• The design provides a sensitive, label-free, non-destructive optical tool for single molecule manipulation.
• The system requires low trapping intensity and minimizes photodegradation.