Preparation,Structure And Optical Properties Of Patterned Glass Ceramics For High Brightness And High Quality Laser Lighting Applications

InGaN-based light-emitting diode（LED）chips have the problem of“efficiency droop”,which makes it difficult to achieve high-power,high-brightness white light illumination based on a single LED chip.To solve this problem,laser lighting technology came into being.Laser diodes（LDs）have the advantages of no“efficiency droop”,high brightness,and low etendue,and are far superior to LEDs in terms of energy density,energy efficiency,and light directionality.However,it is subject to the energy loss of light conversion under high photon flux,and a large amount of heat is generated when fluorescent material is irradiated by a high-power laser,which puts forward extremely high requirements on its stability and conduction/heat dissipation.The traditional silicon-encapsulated phosphor technology will be severely carbonized under laser irradiation and cannot be applied.The development of all-inorganic fluorescent conversion materials is an inevitable choice.Fluorescent glass ceramics（also known as glass-ceramics）have many advantages,such as low preparation cost,flexible composition design,and controllable chromaticity by mixing multiphase phosphors,and have received great attention from academia and industry in recent years.In this paper,focusing on this type of composite materials,two new patterned glass-ceramic integrated materials were obtained based on reasonable material design and low-temperature co-firing route preparation:Ca Al Si N₃:Eu²⁺glass-ceramic film（phosphor-in-glass film,PiGF）-Y₃Al₅O₁₂:Ce³⁺glass ceramic plate（phosphor-in-glass plate,PiGP）,and Ca Al Si N3:Eu²⁺PiGF-Lu₃Al₅O₁₂:Ce³⁺PiGF-high thermal conductivity sapphire substrate;Furthermore,by constructing a“fluorescence wheel”light engine,good light and color performance output is achieved under the excitation of high-power blue laser,and it is expected to construct a high-quality laser illumination source.The specific work is as follows:（1）Chromaticity-tunable CASN:Eu PiGF-YAG:Ce PiGP glass-ceramic composites designed with“fluorescent pattern”.The latest laser illumination technologies face the challenge of achieving good photometric and colorimetric performance at the same time.Based on the new architecture of sintered Ca Al Si N₃:Eu²⁺PiGF on Y₃Al₅O₁₂:Ce³⁺PiGP,the coupling of“patterned package design”and“fluorescence wheel”was proposed and proved to effectively solve this problem.The fabricated composite has no interface between the two functional layers,and relatively intactly retains the excellent luminescence characteristics of Ca Al Si N₃:Eu²⁺and Y₃Al₅O₁₂:Ce³⁺to achieve microstructural integrity during co-sintering.A study of the laser-crystallite interaction revealed that the luminescence saturation of Y₃Al₅O₁₂:Ce³⁺is almost determined by thermal quenching,but ascribed to an equally important thermal/intensive quenching for Ca Al Si N₃:Eu²⁺.Benefiting from the fine architectural design,good chromaticity tunability is obtained and severe photon reabsorption is reduced;moreover,with the rotation-induced increase in thermal convection to the air and pulse-like excitation,the constructed blue laser The driven lighting engine shows bright white light with a luminous flux higher than 1000 lm,the chromaticity is adjustable from cold to warm,and the color rendering index is close to70.（2）Patterned CASN:Eu-Lu AG:Ce PiGF-sapphire integrated composites for high color-quality laser illumination.High-quality laser-driven illumination sources require not only high brightness,but also a uniform spectral distribution.In this work,green Lu₃Al₅O₁₂:Ce³⁺and red Ca Al Si N₃:Eu²⁺commercial phosphors were co-fired with Si-based low-melting glass,and sequentially sintered on a high thermal conductivity sapphire substrate in the form of a glass-ceramic film,and the patterned structure was designed.The large-scale"fluorescence wheel"used for driving by a micro motor is pumped by blue laser light under the reflection excitation light path.Thanks to the heat dissipation effect of the“heat sink”of the high thermal conductivity sapphire substrate and the pulse rotation excitation mode,the thermal load of the phosphor is greatly reduced,and the occurrence of luminescence saturation is effectively delayed.Systematic experiments combined with theoretical calculations have proved that the photon reabsorption problem occurred in the traditional“hybrid phosphor”structure has been well resolved under the“fluorescence patterning”structure design,which mediates the“luminosity-color”structure to a certain extent.degree of contradiction,and will not cause uneven spatial color distribution.The laser-driven green light source based on Lu₃Al₅O₁₂:Ce³⁺glass ceramics can achieve high brightness of 2970 lm@21W/mm²,and the white light source based on patterned Ca Al Si N₃:Eu²⁺PiGF-Lu₃A_l5O₁₂:Ce³⁺PiGF can simultaneously achieve luminous flux higher than 1000 lm and color rendering Light color output with an index greater than 80.