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Published on: May 10, 2014
Radiation efficiency of partially coherent electromagnetic beams
1Department of Physics-Optics, Royal Institute of Technology, Stockholm, Sweden. po@optics.kth.se
Summary
We defined radiation efficiency for electromagnetic fields, showing it measures how directed beams are. This efficiency is generally between 0 and 1, regardless of coherence or polarization.
Area of Science:
- Optics and Photonics
- Electromagnetism
- Wave Phenomena
Background:
- Understanding the directionality of electromagnetic beams is crucial in optics.
- Existing metrics may not fully capture the behavior of partially coherent fields.
Purpose of the Study:
- To introduce a general definition for the radiation efficiency of stationary electromagnetic fields.
- To analyze how radiation efficiency relates to beam properties like coherence and polarization.
- To assess the directionality of specific partially coherent electromagnetic beams.
Main Methods:
- Developed a general mathematical definition for radiation efficiency.
- Proved the bounds of radiation efficiency (0 to 1) for various beam types.
- Evaluated radiation efficiency for azimuthally polarized and dipolar beams.
Main Results:
- Radiation efficiency is universally bounded between 0 and 1.
- Efficiency is a measure of beam directionality, sensitive to spatial coherence and intensity variations.
- Efficiency is largely independent of polarization state.
- Efficiency deviates from unity primarily for beams with small source and correlation widths.
Conclusions:
- The proposed radiation efficiency offers a robust metric for beam directionality.
- Partially coherent beams, even with specific polarization, exhibit efficiency limitations tied to their spatial characteristics.
- The findings are applicable to diverse electromagnetic beam applications.
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