# US 2018/0025182 A1 · Phosphor-Loaded Waveguide > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0025182 A1 - Document ID: US20180025182A1 - Status: Published application - Kind: A1 - Application number: 15/548,027 - Filed: 2016-02-29 - Published: 2018-01-25 - Earliest claimed: 2015-03-09 - Assignees: Massachusetts Institute of Technology - Applicants: Massachusetts Institute Of Technology - Inventors: Michael W. Geis; Joshua Kramer; Karen M.G.V. Gettings; Marc J. Burke; Mankuan M. Vai; Theodore M. Lyszczarz - Web page: https://patentgrep.com/patent/US20180025182A1 ## CPC - G06F 21/70: Protecting specific internal or peripheral components, in which the protection of a component leads to protection of the entire computer - G02B 6/0003: {the light guides being doped with fluorescent agents} - G02B 6/4214: {the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device (G02B6/4246 takes precedence)} - G02B 6/4298: {coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers} - G06F 21/72: in cryptographic circuits - G06V 20/80: Recognising image objects characterised by unique random patterns - H04L 63/04: {for providing a confidential data exchange among entities communicating through data packet networks} - H04L 63/162: {at the data link layer} - G02B 6/4215: {the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers (G02B6/4246 takes precedence)} - G02B 6/4295: {coupling with semiconductor devices activated by light through the light guide, e.g. thyristors, phototransistors} - G02B 6/43: Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections - G06V 20/95: {Pattern authentication; Markers therefor; Forgery detection} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An improved waveguide is disclosed. The waveguide utilizes a luminescent material disposed within or around its perimeter to introduce additional light into the waveguide. For example, the waveguide may include a plurality of planar layers having different refractive indexes. A luminescent material may be disposed along the outer edge of these layers. When light from within the waveguide strikes the luminescent material, it emits light, thereby adding to the light in the waveguide. Not only does the luminescent material introduce more light into the waveguide, it also introduces more light sources, thereby making it more difficult to introduce a probe without blocking at least a portion of the light destined for the image sensor. The luminescent material may be a phosphor. ## Claims ### Claim 1 A waveguide, comprising: an assembly comprising an inner core, having a first refractive index; and an outer cladding, covering at least a portion of the inner core, having a second refractive index, wherein the assembly forms a thin rectangular prism; and a luminescent material disposed on an edge of the assembly, where the edge is perpendicular to longer dimensions of the assembly. ### Claim 2 (depends on 1) The waveguide of claim 1, wherein the luminescent material is disposed on an entire perimeter of the assembly. ### Claim 3 (depends on 1) The waveguide of claim 1, wherein the luminescent material comprises a phosphor. ### Claim 4 (depends on 1) The waveguide of claim 1, wherein the second refractive index is less than the first refractive index. ### Claim 5 (depends on 1) The waveguide of claim 1, wherein the outer cladding sandwiches the inner core. ### Claim 6 (depends on 1) A physically unclonable function, comprising: a printed circuit board; and the waveguide of claim 1, disposed on the printed circuit board; wherein the printed circuit board comprises: a light source for emitting a light into the waveguide; and an image sensor for receiving a light pattern creating by the light traversing the waveguide. ### Claim 7 (depends on 6) The physically unclonable function of claim 6, wherein the printed circuit board further comprises: a processing unit; a memory element containing encrypted code to be executed by the processing unit; and a decryption circuit to decrypt the encrypted code stored in the memory element, wherein the light pattern is used to create a key used by the decryption circuit. ### Claim 8 (depends on 7) The physically unclonable function of claim 7, wherein the processing unit and the decryption circuit are disposed beneath the waveguide. ### Claim 9 (depends on 8) The physically unclonable function of claim 8, wherein the memory element is disposed beneath the waveguide. ### Claim 10 (depends on 6) The physically unclonable function of claim 6, wherein the light source emits light having a first wavelength, and the luminescent material absorbs the light having the first wavelength, and emits light having a second wavelength, greater than the first wavelength. ### Claim 11 (depends on 6) The physically unclonable function of claim 6, wherein the light source comprises a blue light source. ### Claim 12 (depends on 11) The physically unclonable function of claim 11, wherein the luminescent material is a phosphor that absorbs blue light and emits red light. ### Claim 13 (depends on 6) The physically unclonable function of claim 6, further comprising an optical filter disposed between the waveguide and the image sensor. ### Claim 14 (depends on 6) The physically unclonable function of claim 6, wherein the image sensor is a color image sensor. ### Claim 15 (depends on 6) The physically unclonable function of claim 6, wherein the luminescent material is disposed on an entire perimeter of the assembly. ### Claim 16 A waveguide, comprising: an assembly comprising an inner core, having a first refractive index; and an outer cladding, covering at least a portion of the inner core, having a second refractive index, wherein the assembly forms a thin rectangular prism; and a luminescent material disposed on an interior of the assembly. ### Claim 17 (depends on 16) The waveguide of claim 16, wherein the luminescent material is disposed within the inner core. ### Claim 18 (depends on 16) The waveguide of claim 16, wherein the luminescent material is disposed within the outer cladding. ### Claim 19 (depends on 16) A physically unclonable function, comprising: a printed circuit board; and the waveguide of claim 16, disposed on the printed circuit board; wherein the printed circuit board comprises: a light source for emitting a light into the waveguide; and an image sensor for receiving a light pattern creating by the light traversing the waveguide. ### Claim 20 (depends on 19) The physically unclonable function of claim 19, wherein the printed circuit board further comprises: a processing unit; a memory element containing encrypted code to be executed by the processing unit; and a decryption circuit to decrypt the encrypted code stored in the memory element, wherein the light pattern is used to create a key used by the decryption circuit, wherein the processing unit and the decryption circuit are disposed beneath the waveguide.