Laser spot associated high-saturation phosphor-in-glass film for transmissive and reflective high-brightness laser lighting

Phosphor-in-glass (PiG) film is a promising luminescent material in high-brightness laser lighting for its advantages of high efficiency, outstanding color quality, and low-cost preparation, which must bear high laser power (LP) and laser power density (LPD) simultaneously to enable high-luminance light. Herein, laser spot associated high-saturation PiG film was proposed for transmissive and reflective high-brightness laser lighting. Two types of PiG films were prepared by printing and sintering La₃Si₆N₁₁:Ce³⁺ (LSN) phosphor-borosilicate glass pastes on a sapphire substrate (PiG-S) and an AlN substrate (PiG-A), respectively. The PiG films with perfect crystal structure of phosphor were reliably bonded on the substrates. The effects of laser spot areas on the luminescence saturation of LP and LPD were investigated in the PiG films. With the increase of laser spot area from 0.5 to 2.5 mm², the LP threshold of PiG films is gradually raised, while the LPD threshold of PiG films is decreased. The PiG-S withstands a high LP of 23.46 W and a high LPD of 20.64 W/mm², enabling white light with a luminous flux of 3677 lm. The PiG-A withstands a high LP of 41.12 W and a high LPD of 35.56 W/mm², enabling white light with a luminous flux of 2882 lm. Moreover, the PiG-A maintains lower working temperature compared with the PiG-S, and the temperatures reduce with the increasing laser spot area. The results demonstrate that the laser spot associated PiG films realize high saturation thresholds of LP and LPD simultaneously, and enable high luminance for laser lighting.