Improved efficiency of planar light converters based on Al2O3-YAG:Ce eutectic crystals: Physical Trends and Limits

TL;DR

This paper presents a theoretical and experimental study of Al2O3-YAG:Ce eutectic crystal light converters, demonstrating a doubled efficiency compared to single crystal versions, and explores physical limits and optimization of their optical parameters.

Contribution

It introduces a new theoretical model for crystalline light converters with internal scattering, and provides experimental validation showing doubled efficiency over single crystal counterparts.

Findings

Efficiency of 16% for Al2O3-YAG:Ce eutectic converters

Theoretical model estimates efficiency based on optical and geometrical parameters

Physical limits of efficiency enhancement due to internal scattering

Abstract

A theoretical model of a crystalline converter of white light with internal scattering medium is proposed. Obtained are the expressions for estimation of the light converter efficiency depending on its optical parameters (refractive index and coefficients of absorption at the wavelengths of the incident and re-emitted light), as well as on the geometrical dimensions and the scattering indicatrix of the optical system. The physical limits of improvement of the converter efficiency due to strong internal scattering, are established. Realized are the theoretical and experimental estimations of the efficiency of the light converter based on the crystals of Al2O3-YAG:Ce eutectic alloy which amounts to 16%. This is twice as high in comparison with the efficiency of the light converter based on YAG:Ce single crystal.