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Light emission from whispering-gallery modes in microscopic spheres
Michael J Jory1, Elaine A Perkins, J Roy Sambles
1Thin Film Photonics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK. mjjory@exeter.ac.uk
Summary
Researchers studied light emission from whispering-gallery modes in microscopic spheres. They used an evanescent wave to excite these modes and measured the emitted light intensity, comparing it to theoretical predictions.
Area of Science:
- Optics and Photonics
- Condensed Matter Physics
Background:
- Whispering-gallery modes (WGMs) are resonant modes of light confined within dielectric spheres.
- Exciting WGMs in microscopic spheres is crucial for applications in sensing and lasers.
- Evanescent waves offer a non-contact method for light excitation at interfaces.
Purpose of the Study:
- To investigate the excitation of whispering-gallery modes in microscopic spheres using an evanescent wave.
- To measure the angular distribution of light emission from excited WGMs.
- To compare experimental results with theoretical models for light emission.
Main Methods:
- Generating an evanescent wave via total internal reflection at a planar glass-air interface.
- Using the evanescent wave to excite WGMs in single microscopic spheres positioned near the interface.
- Measuring the intensity of emitted light as a function of scattering angle for p- and s-polarized incident light.
Main Results:
- Observed light emission from whispering-gallery modes in microscopic spheres.
- Measured the angular intensity distribution of emitted light for different polarizations.
- Found good agreement between experimental data and a simple theoretical model for emission from a point source.
Conclusions:
- Evanescent waves effectively excite whispering-gallery modes in microscopic spheres.
- The angular emission pattern provides insights into the WGM excitation process.
- The study validates a theoretical framework for understanding light emission from WGMs in micro-spheres.