Laser-excited single crystal phosphor in white LED for wide field of view and high enhanced central brightness for vehicle headlights

Abstract

We demonstrate the generation of a laser hotspot by a laser-excited single crystal phosphor (SCP) converter layer in a white LED for producing a wide field of view (FOV) and high enhanced central brightness (ECB) for an adaptive-driving-beam (ADB) headlight. The SCP layer shows better thermal quench behavior than other phosphor converter layers because of the higher melting temperature of 1940 °C and larger thermal conductivity of 11 W/m°C. The advantage of this study is an optical design of the ADB headlight, in which the generation, mechanism, and characterization of the laser hotspot are investigated in detail. The proposed scheme enables a wide FOV of ±16.8° and high ECB of the high beam, compliant with the Economic Commission for Europe regulation of vehicle headlights. The wide FOV provides better visibility, while the high ECB improves the long-distance illumination of the headlights. This proposed ADB headlight is a promising headlight candidate for use in the next-generation autonomous vehicle applications.