OPTICAL LIGHT GUIDE INCLUDING FLUORESCENT MATERIAL

1 . An optical light guide, comprising a core including a fluorescent material, wherein the fluorescent material is in a content of greater than 0.5 wt. % for a total weight of the core.

2 . The optical light guide of claim 1 , wherein the core comprises polyethylene naphthalate (PEN).

3 . The optical light guide of claim 2 , further comprising a cladding, wherein the cladding comprises polyvinylidene difluoride.

4 . The optical light guide of claim 2 , wherein the fluorescent material is in a content of between 0.6 wt. % and 1.4 wt. % for a total weight of the core.

5 . The optical light guide of claim 1 , wherein the optical light guide has at least one dimension of height, width, or diameter that is less than 40 microns.

6 . The optical light guide of claim 1 , wherein the optical light guide produces>4 mW/mm 2 of optical power emission out at least one end of the optical light guide when illuminated with 50 mW/mm 2 of light composed of a wavelength of 470 nm.

7 . The optical light guide of claim 1 , wherein the fluorescent material comprises a wavelength shifting material.

8 . The optical light guide of claim 1 , wherein the fluorescent material is in the content of at least 0.5 wt. % and at most 40 wt. % for a total weight of the core.

9 . The optical light guide of claim 1 , wherein the optical light guide has a thickness of at least 20 microns and at most 40 microns.

10 . The optical light guide of claim 1 , wherein the fluorescent material comprises p-terphenyl (C 18 H 14 ), 2,5-diphenyloxazole (PPO, C 15 H 11 NO), 1,1,4,4,-tetraphenylbutadiene (TBP, C 28 H 22 ), 1,2,4-trimethyl benzene (C 9 H 12 ), Indolcarbonasureester (C 23 H 19 NO 4 ), dimethyl stilbene (DP S, C 26 H 18 ), bis-MSB (C 24 H 22 ), dimethyl POPOP (C 26 H 20 N 2 O), K27 (C 23 H 19 NO 4 ), or tris [1-phenylisoquinolinato] iridium (III) (C 15 NlrH 10 ).

11 . An optical light guide, comprising a core including a fluorescent material and a cladding layer surrounding the core, wherein the fluorescent material is in a content of greater than 0.5 wt. % for a total weight of the core, wherein the optical light guide comprises a refractive index difference between the core and the cladding layer, wherein an absolute value of the difference is at least 0.1.

12 . The optical light guide of claim 11 , wherein the core comprises polystyrene, polyacrylate, polymethylmethacrylate, polyvinyltoluene, polyethylene naphthalate (PEN), or any combination thereof.

13 . The optical light guide of claim 11 , wherein the core has a refractive index of at least 1.45.

14 . The optical light guide of claim 11 , wherein the cladding layer has a refractive index less than the refractive index of the core.

15 . The optical light guide of claim 11 , wherein the cladding layer has a refractive index of at most 1.40.

16 . The optical light guide of claim 11 , wherein the fluoropolymer comprises ethylene tetrafluoroethylene (ETFE), perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), or any combination thereof.

17 . The optical light guide of claim 11 , wherein the optical light guide has a light trapping efficiency of at least 15%.

18 . The optical light guide of claim 11 , wherein the optical light guide is embedded within a security document.

19 . The optical light guide of claim 18 , wherein a light-exiting end is aligned with an edge of the security document, and a radiation-receiving end is aligned with an opposite edge of the security document.

20 . An anti-counterfeiting paper, comprising a layer structure; and an optical light guide within the layer structure, wherein the optical light guide comprises a core including a fluorescent material, wherein the fluorescent material is in a content of greater than 0.5 wt. % for a total weight of the core.