Optical Performance Analysis of UVC-LED Package Structure Based on Ray-Tracing Simulation

Abstract

UVC-LED medical sterilization technology is widely used nowadays. Due to the refractive index of the UVC-LED light-emitting layer is too different from the refractive index of air, the light difficult for light to escape from the inside of the LED. The light extraction efficiency of the UVC-LED chip is very low, and the light penetration of this wavelength band is extremely weak, so the luminous flux of the UVC-LED chip is very low. This article optimizes the existing package structure to increase the luminous flux. First, a traditional package structure model was built and analyzed using the method of ray-tracing simulation. Secondly, a new model including brackets with different angles and different reflective layers was built. Different reflective coatings were used and evaluated in the simulation. Finally, the simulation data were sorted out and the luminous flux of different reflective coatings under the same bracket tilt angle and the luminous flux of the same reflective coating with different bracket tilt angles were compared. Through the comparison of simulation results, it can be concluded that with the same reflective coating, the luminous flux effect is better when the tilt angle of the bracket is between <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${40^{\mathrm{o}}\ \text{and}\ 70^{\mathrm{o}}}$</tex> , T he luminous flux will be increased by about 30% after using the reflective coating under the same structure. For a circular package, the best radiation intensity occurs near the tilt angle of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${45^{\circ}}$</tex> . For the square pack age, the best radiation intensity occurs near the tilt angle of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${60^{\circ}}$</tex> . Finally, from the perspective of overall optical performance, the packaging structure of the circular cavity is more suitable for UVC-LED packaging than the square cavity. This research guides the development of UVC-LED packaging routes.