Infrared emitting device
Embodiments of the invention include a light source and a wavelength converting structure disposed in a path of light emitted by the light source. The wavelength converting structure includes a first phosphor that emits infrared light and a second phosphor that emits visible light. In some embodiments, the light source emits first light, the second phosphor absorbs the first light and emits second light, and the first phosphor absorbs the first light and emits third light and absorbs the second light and emits fourth light.
1. A device comprising:
a light source emitting a first light; and
a wavelength converting structure disposed in a path of the first light emitted by the light source, the wavelength converting structure comprising:
a first phosphor; and
a second phosphor;
the second phosphor absorbing the first light and emitting a second light, which second light is visible light, the first phosphor absorbing the first light and emitting a third light, the first phosphor absorbing the second light and emitting a fourth light, the third light and the fourth light have different peak wavelengths in the infrared emission range.
2. The device of claim 1 wherein the first light is blue light and the second light is red light.
3. The device of claim 1 wherein the first phosphor comprises a Cr(III) phosphor that is excited by the first light via 4 A 2 →T 1 electron transitions and is excited by the second light via 4 A 2 →T 2 electron transitions.
4. The device of claim 1 wherein the first phosphor comprises a crystalline phosphor material made up of an ordered structure with more than one substitutional position for a dopant.
5. The device of claim 1 wherein the first phosphor comprises one of a solid solution and a mixed crystal type phosphor where different crystal types emit via different emission channels.
6. The device of claim 1 wherein the first phosphor comprises a glass or amorphous material.
7. The device of claim 1 wherein the first phosphor comprises RE 3 Ga 5-x-y A x SiO 14 :Cr y (RE=La, Nd, Gd, Yb, Tm; A=Al, Sc), where 0≤x≤1 and 0.005≤y≤0.1.
8. The device of claim 1 wherein the first and second phosphors are mixed with a transparent material and disposed over the light source.
9. The device of claim 1 , wherein the first phosphor comprises trivalent cations as emitting centers.
10. The device of claim 1 , wherein the first phosphor comprises a host lattice comprising tetravalent cations.
11. The device of claim 10 , wherein the tetravalent cation is Si 4 .
12. The device of claim 1 , wherein the first phosphor comprises Cr(IV), a amount of Cr(IV) in the first phosphor being less than 10% total chromium content in the first phosphor.
13. The device of claim 1 , wherein the first phosphor comprises Cr(IV), a amount of Cr(IV) in the first phosphor being less than 5% total chromium content in the first phosphor.
14. The device of claim 1 , wherein the first phosphor comprises Cr(IV), a amount of Cr(IV) in the first phosphor being less than 1% total chromium content in the first phosphor.
15. The device of claim 1 , wherein the first phosphor comprises a host lattice belonging to a trigonal calcium gallogermanate structure family crystallizing in polar space group P321.
16. The device of claim 1 , wherein the first phosphor comprises La 3 Ga 5y SiO 14 :Cr y .
17. The device of claim 1 , wherein the first phosphor comprises Gd 3-x RE x Sc 2-y-z Ln y Ga 3-w Al w O 12 :Cr z , where Ln=Lu, Y, Yb, Tm; RE=La, Nd, 0≤X ≤3; 0≤y ≤1.5; 0≤z ≤0.3 and 0≤w ≤2.
18. The device of claim 1 , wherein the first phosphor comprises AAEM 1-x F 6 :Cr x , where A=Li, Cu; AE=Sr, Ca; M=Al, Ga, Sc; and 0.005≤x ≤0.2.
19. The device of claim 7 , wherein the first phosphor comprises Gd 3-x RE x Sc 2-y-z Ln y Ga 3-w Al w O 12 :Cr z , where Ln=Lu, Y, Yb, Tm; RE=La, Nd, 0≤X ≤3; 0≤y ≤1.5; 0≤z ≤0.3 and 0≤w ≤2.
20. The device of claim 7 , wherein the first phosphor comprises AAEM 1-x F 6 :Cr x , where A=Li, Cu; AE=Sr, Ca; M=Al, Ga, Sc; and 0.005≤x ≤0.2.