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Updated: Jan 25, 2026
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Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
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Free-space coupling to symmetric high-Q terahertz whispering-gallery mode resonators
Optics Letters
|May 2, 2019
Summary
We demonstrate efficient free-space coupling of Gaussian beams to terahertz whispering-gallery mode resonators. This method achieves high excitation efficiencies for terahertz whispering-gallery mode resonators, showing promise for THz applications.
Area of Science:
- Optics and Photonics
- Terahertz Science and Technology
Background:
- Whispering-gallery mode resonators (WGMRs) are crucial for various optical applications.
- Efficiently coupling light into WGMRs, especially in the terahertz (THz) range, remains a challenge.
Purpose of the Study:
- To investigate the free-space coupling of Gaussian beams to high-quality terahertz whispering-gallery mode resonators.
- To achieve high excitation efficiencies for terahertz whispering-gallery mode resonators.
Main Methods:
- Utilized a free-space Gaussian beam with a diffraction-limited focal spot.
- Employed low-loss, high-index silicon spheres as terahertz whispering-gallery mode resonators with diameters near the wavelength.
- Measured excitation efficiencies at 0.7 THz.
Main Results:
- Achieved very high excitation efficiencies up to 50% for terahertz whispering-gallery mode resonators.
- Demonstrated a high quality (Q)-factor of 1.5×10^4 at 0.7 THz.
- Validated the effectiveness of free-space coupling for terahertz radiation.
Conclusions:
- Free-space coupling is a viable and efficient method for exciting terahertz whispering-gallery mode resonators.
- The use of silicon spheres and optimized Gaussian beams facilitates high coupling efficiencies in the THz range.
- This work paves the way for advanced terahertz devices and applications.
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