An Efficient Optothermal Simulation Framework for Optimization of High-Luminance White Light Sources

Laser diodes are very promising solid-state devices for the development of high-luminance white light sources. Currently, the most simple and efficient way to produce white light with solid-state sources is to combine them with color-converting luminescent materials or phosphors. The quantum yield (i.e., the potential to convert light to another color) of these materials has complex dependence on temperature. In the case of high-power white light sources based on laser diodes, high temperatures are reached inside the phosphor material, which decrease its quantum yield (thermal quenching) and result in a nonstable light output. While this thermal quenching effect is well known, the tools used today to design and optimize optical systems do not include it in a realistic way. This work fills that gap by proposing an automated framework that simulates both the optical and thermal effects and the interplay between them. Additionally, an adapted version of the framework is also proposed, which is more computationally efficient. The resulting shorter simulation time is crucial for the efficient optimization of the optothermal performance of lighting systems, which requires several iterations of the framework for each optimization variable. The optothermal simulation framework has been applied to some optical designs to study them by changing certain optical and thermal properties and evaluating how these affect the overall performance. It is clearly demonstrated that even for optical designs that use LED sources, neglecting the thermal effects of luminescent materials can lead to an incorrect assessment of the system's capabilities and performance.