Composition and luminescence properties of highly robust green-emitting LuAG:Ce/Al_(2)O_(3)composite phosphor ceramics for high-power solid-state lighting

The major advantage of laser lighting over white light-emitting-diode is the possibility to achieve ultra-high luminance.However,phosphors usually suffer laser-induced luminescence saturation,which limits the peak luminance of laser lighting devices.The aim of the present study is to develop LuAG:Ce/Al_(2)O_(3)composite ceramics(LACCs)with a high saturation threshold for high-luminance laser lighting.Owning to the rigid crystal structure,proper synthetic process,and optimized thermal design,the LACCs possess small thermal quenching(16%loss in luminescence at 225℃),high quantum yield(>95%),and excellent luminescence properties.When the LACCs are irradiated by blue laser diodes in a reflection mode,a high luminous flux of 4634 lm and luminous efficacy of 283 lm·W^(−1)are realized.Furthermore,they show no sign of luminescence saturation even when the power density reaches 20.5 W·mm^(−2).With these favorable properties,the designed LACCs show great potential in high-luminance laser lighting.

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 La_(3)Si_(6)N_(11):Ce^(3+)(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 mm^(2),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/mm^(2),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/mm^(2),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.

Saturation effect of up-conversion luminescence from erbium-doped,silicatitania sol-gel powders

The intensity of the visible up-conversion luminescence could be limited by a saturation effect produced by increased pump power. Visible up-conversion luminescence was obtained in erbium doped,silica-titania sol gel powders under dynamical pumping at 1532 nm. The saturation effect was studied for erbium radiative transitions 2H9/2→4I15/2 （410 nm）,2H11/2→4I15/2 （530 nm）,4S3/2→4I15/2 （550 nm）,2H9/2→4I13/2 （567 nm） and 4F9/2→4I15/2 （675 nm）. The recorded up-conversion luminescence decreased when increasing excitation power. The results suggested that the saturation effect was determined by the pump power,the sample composition and the lifetimes of the corresponding first excited states.