Glass composites having a gradient index of refraction and methods for production thereof
Gradient refractive index (GRIN) materials can include multi-phase composites having substances with differing refractive indices disposed non-uniformly within one another. Particular glass composites having a gradient index of refraction can include: an amorphous phase, and a phase-separated region disposed non-uniformly within the amorphous phase. The glass composites include a mixture containing: GeZ 2 and A 2 Z 3 in a combined molar ratio of about 60% to about 95%, and CsX and PbZ in a combined molar ratio of about 5% to about 40%, where A is As, Sb or Ga, X is Cl, Br or I, and Z is S or Se. When A is As, the glass composites include PbZ in a molar ratio of about 15% or less. The amorphous phase and the phase-separated region have refractive indices that differ from one another. More particularly, A is Ga or As, X is Cl, and Z is Se.
1. A glass composite having a gradient index of refraction, comprising:
an amorphous phase; and
a phase-separated region disposed non-uniformly within the amorphous phase;
wherein the amorphous phase has a first index of refraction, and the phase-separated region has a second index of refraction, the first index of refraction differing from the second index of refraction; and
wherein the glass composite comprises a mixture comprising:
GeZ 2 and A 2 Z 3 in a combined molar ratio of about 60% to about 95%, and
CsX and PbZ in a combined molar ratio of about 5% to about 40%;
wherein A is As, Sb or Ga, X is Cl, Br or I, and Z is S or Se; and
wherein the glass composite comprises PbZ in a molar ratio of about 15% or less when A is As.
2. The glass composite of claim 1 , wherein A is Ga or As, X is Cl, and Z is Se.
3. The glass composite of claim 2 , wherein the mixture comprises:
GeSe 2 in a molar ratio of about 20% to about 30%, and
As 2 Se 3 in a molar ratio of about 65% to about 75%.
4. The glass composite of claim 3 , wherein the mixture comprises PbSe in a molar ratio of about 5% to about 15%.
5. The glass composite of claim 4 , wherein a molar ratio of CsCl is 0%.
6. The glass composite of claim 2 , wherein the mixture comprises:
GeSe 2 in a molar ratio of about 40% to about 60%, and
Ga 2 Se 3 in a molar ratio of about 20% to about 30%.
7. The glass composite of claim 6 , wherein the mixture comprises:
CsCl in a molar ratio of about 20% to about 30%, and a molar ratio of PbSe is 0.
8. The glass composite of claim 6 , wherein the mixture comprises:
CsCl in a molar ratio of about 0% to about 10%, and
PbSe in a molar ratio of about 5% or above.
9. The glass composite of claim 8 , wherein the molar ratio of PbSe is about 5% to about 30%.
10. The glass composite of claim 8 , wherein the PbSe comprises a plurality of crystallites in the phase-separated region.
11. The glass composite of claim 10 , wherein the PbSe is present in a nanocrystalline form.
12. The glass composite of claim 1 , wherein the glass composite has a transmission window of at least about 1 micron to about 12 microns.
13. The glass composite of claim 1 , wherein the first index of refraction and the second index of refraction differ by a value of up to about 1.
14. An optical structure comprising the glass composite of claim 1 .
15. The optical structure of claim 14 , wherein the glass composite defines a lens.
16. A method comprising:
providing a mixture comprising:
GeZ 2 and A 2 Z 3 in a combined molar ratio of about 60% to about 95%, and
CsX and PbZ in a combined molar ratio of about 5% to about 40%;
wherein A is As, Sb or Ga, X is Cl, Br or I, and Z is S or Se; and
wherein the mixture comprises PbZ in a molar ratio of about 15% or less when A is As;
heating the mixture to form a melt;
cooling the melt below a glass transition temperature thereof to form an intermediate amorphous material; and
locally heating the intermediate amorphous material to define a phase-separated region within an amorphous phase;
wherein the amorphous phase has a first index of refraction, and the phase-separated region has a second index of refraction, the first index of refraction differing from the second index of refraction; and
wherein the phase-separated region is disposed non-uniformly within the amorphous phase.
17. The method of claim 16 , wherein the mixture comprise:
GeSe 2 in a molar ratio of about 20% to about 30%, and
As 2 Se 3 in a molar ratio of about 65% to about 75%.
18. The method of claim 17 , wherein the mixture comprises PbSe in a molar ratio of about 5% to about 15%.
19. The method of claim 17 , wherein a molar ratio of CsCl is 0%.
20. The method of claim 16 , wherein A is Ga or As, X is Cl, and Z is Se.
21. The method of claim 20 , wherein the mixture comprises:
GeSe 2 in a molar ratio of about 40% to about 60%, and
Ga 2 Se 3 in a molar ratio of about 20% to about 30%.
22. The method of claim 21 , wherein the mixture comprises:
CsCl in a molar ratio of 0% to about 10%, and
PbSe in a molar ratio of about 5% or above.
23. The method of claim 21 , wherein the mixture comprises:
CsCl in a molar ratio of about 20% to about 30%, and a molar ratio of PbSe is 0.
24. The method of claim 16 , wherein locally heating the intermediate amorphous material comprises spot heating of a plurality of locations in the intermediate amorphous material with a laser.