Whispering-gallery modes promote enhanced optical backflow in a perforated dielectric microsphere

Area of Science:

• Optics and Photonics
• Nanotechnology
• Optical Physics

Background:

• Optical energy typically follows the wave vector in dielectric microspheres.
• Resonance with whispering-gallery modes (WGMs) can induce reverse energy flow in the shadow hemisphere.
• This reverse energy flow region has potential for enhanced optical trapping.

Purpose of the Study:

• To investigate the optical energy flow in a perforated microsphere with a pinhole.
• To analyze the excitation of WGMs in nanostructured microspheres.
• To explore the potential of perforated microspheres as efficient optical tweezers.

Main Methods:

• Numerical analysis of WGM excitation in a perforated microsphere with an air-filled pinhole.
• Simulation of optical energy flow dynamics within the nanostructured microsphere.

Main Results:

• A pinhole effectively isolates the energy backflow region of resonant WGMs.
• The perforated microsphere functions as an efficient optical tweezer.
• A multiple enhancement of energy backflow intensity in the pinhole at WGM resonance was observed for the first time.

Conclusions:

• Perforated microspheres with pinholes offer a novel approach to manipulating optical energy flow.
• These structures demonstrate significant potential for advanced optical trapping applications.
• The revealed energy backflow enhancement can be further manipulated for specific applications.