Nearly Index-Matched Luminescent Glass-Phosphor Composites for Photonic Applications

Abstract

A light emitting device includes a light emitting diode (LED); a transparent optic having a refractive index n optic ; and a phosphor layer spaced apart from the LED and positioned between the LED and the transparent optic. The phosphor layer has an effective refractive index n phosphor , where a gap between the LED and the phosphor layer has a refractive index n gap that is less than n phosphor . The transparent optic has an inner convex surface in contact with the phosphor layer. The inner convex surface has an inner radius of curvature r; and an outer convex surface facing away from the phosphor layer and being a surface through which the light emitting device emits light into a medium adjacent the outer convex surface. The medium has a refractive index n medium . The outer convex surface has an outer radius of curvature R, such that r/R is equal to n medium /n optic .

1 - 22 . (canceled) 
     
     
         23 . A light emitting device comprising:
 a light source configured to emit light comprising a first wavelength;   a light emitting composite material separated from the light source by an air gap and comprising:
 a transparent material; and 
 a plurality of phosphor particles suspended within the transparent material, wherein a refractive index of the phosphor particles is approximately equal to a refractive index of the transparent material and the phosphor particles are configured to absorb the light comprising the first wavelength and emit light comprising a second wavelength; and 
   an optic in contact with the light emitting composite material and having a refractive index greater than 90% of an effective refractive index of the light emitting composite material, the optic having a non-planar surface facing away from the light emitting composite material and being a surface through which the light emitting device outputs, during operation, the light comprising the second wavelength into a medium adjacent the non-planar surface.   
     
     
         24 . The light emitting device of  claim 23 , wherein the plurality of phosphor particles are composed of an inorganic crystalline material selected from the group consisting of:
 Y x Gd y Al v Ga w O 12 :M 3+ , wherein x+y=3 and v+w=5;   SrGa 2 S 4 :M 2+ ;   SrS:M 2+ ;   X 2 Si 5 N 8 M 2+ ; and   XSi 2 O 2 N 2 :M 2+ , wherein X is selected from the group consisting of Be, Mg, Ca, Sr, and Ba and wherein M is selected from a group consisting of Ce, Eu, Mn, Nd, Pr, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ir, and Pt.   
     
     
         25 . The light emitting device of  claim 23 , wherein the transparent material is an optical glass comprising:
 an amount from about 5% to about 35% of SiO 2 ;   an amount from about 55% to about 88% of PbO;   optionally an amount less than about 10% of B 2 O 3 ;   optionally a combined amount less than about 8% of Na 2 O and K 2 O; and   optionally a combined amount less than about 15% total of TiO 2 , ZrO 2 , La 2 O 3 , ZnO, and BaO.   
     
     
         26 . The light emitting device of  claim 23 , wherein the transparent material is an optical glass comprising:
 an amount from about 21% to about 30% of TiO 2 ;   an amount from about 30% to about 50% of BaO, NaO, BeO, CaO, SrO, CdO, Ga 2 O 3 , In 2 O 3 , or Y 2 O 3 ;   an amount from about 18% to about 24% of Al 2 O 3 ; and   an amount from about 1% to about 10% of SiO 2 , B 2 O 3 , PbO, GeO 2 , SnO 2 , ZrO 2 , HfO 2 , or ThO 2 .   
     
     
         27 . The light emitting device of  claim 23 , wherein the transparent material is a Schott glass. 
     
     
         28 . The light emitting device of  claim 23 , wherein the refractive index of the plurality of phosphor particles is within five percent of the refractive index of the transparent material. 
     
     
         29 . The light emitting device of  claim 23 , wherein the plurality of phosphor particles are composed of Y 3 Al 5 O 12 :Ce 3+  and the transparent material is a Schott glass. 
     
     
         30 . The light emitting device of  claim 23 , wherein the plurality of phosphor particles have a size ranging from about 100 nm to about 1 μm. 
     
     
         31 . The light emitting device of  claim 23 , wherein the plurality of phosphor particles are composed of an inorganic crystalline material having a refractive index of about 1.5 to about 2.8 and the transparent material has a refractive index of about 1.5 to about 2.8. 
     
     
         32 . The light emitting device of  claim 23 , wherein the first wavelength ranges from about 350 nm to about 500 nm. 
     
     
         33 . The light emitting device of  claim 23 , wherein the light source is selected from the group consisting of a laser, and a diode. 
     
     
         34 . The light emitting device of  claim 23 , wherein the light source, the light emitting composite material and the optic are positioned on a planar reflector. 
     
     
         35 . The light emitting device of  claim 23 , wherein the light emitting composite material and the optic are integral. 
     
     
         36 . The light emitting device of  claim 23 , wherein the light emitting composite material and the optic are hemispherical. 
     
     
         37 . The light emitting device of  claim 23 , wherein the light emitting composite material and the optic are spherical. 
     
     
         38 . The light emitting device of  claim 23 , wherein the second wavelength ranges from about 500 nm to about 700 nm.