Optical filtering device
DCFirst Claim
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1. A waveguide device for filtering light, comprising:
- an optical filter, a first section of waveguide, and a second section of waveguide positioned between the first section of waveguide and the optical filter and being in optical communication with the first section of waveguide and the optical filter, the diameter of the second section of waveguide being greater on the end closest to the optical filter than on the end farthest from the optical filter.
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Abstract
A device for filtering light propagating within waveguides, including optical fibers. The device includes an optical filter, a first waveguide section and a second waveguide section positioned between the filter and the first waveguide section. The diameter of the second waveguide section is greater on the end proximate to the optical filter than on the end opposite the optical filter, typically tapering from one end of the second waveguide section to the other. Benefits include reduction of power density, collimation of light for filtering and/or facilitation of optical coupling, and robustness.
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Citations
69 Claims
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1. A waveguide device for filtering light, comprising:
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an optical filter, a first section of waveguide, and a second section of waveguide positioned between the first section of waveguide and the optical filter and being in optical communication with the first section of waveguide and the optical filter, the diameter of the second section of waveguide being greater on the end closest to the optical filter than on the end farthest from the optical filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
wherein at least a portion of light exiting the third waveguide section is incident upon the optical filter and is reflected by the optical filter so as to enter the fourth waveguide section. -
34. The device of claim 33 wherein at least a portion of light propagating within the second waveguide section exits the second waveguide section through the optical filter and enters the fourth waveguide section.
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35. The device of claim 33 further comprising a second optical filter located between the optical filter and the fourth waveguide section.
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36. The device of claim 34, wherein the optical filter adheres to the end face of the fourth waveguide section.
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37. The device of claim 2 wherein the optical filter is a thin-film interference filter.
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38. The device of claim 37 wherein the filter comprises at least 20 layers of alternating refractive index material having a packing density exceeding ninety five percent.
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39. The device of claim 38 wherein the optical filter adheres to an end face of the second waveguide section.
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40. The device of claim 39 wherein the filter is applied by means for depositing a coating of molecules that imparts sufficient energy to the deposited molecules so that the coating of deposited molecules has a packing density exceeding ninety five percent.
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41. The device of claim 40 wherein the deposition means comprises at least one of magnetron sputtering, ion beam sputtering, ion plating and ion-assisted deposition.
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42. The device of claim 2 wherein the second waveguide section comprises a first region of the second waveguide section extending along the longitudinal axis and having a refractive index higher than the refractive index of at least one radially displaced second region of the second waveguide section.
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43. The device of claim 42 wherein there is a step change in refractive index between the first region and the second region.
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44. The device of claim 2 further comprising a coating of internally reflective material applied to the second waveguide section.
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45. The device of claim 44 wherein the coating comprises a metallic material.
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46. The device of claim 44 wherein the coating comprises a low-refractive-index film.
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47. The device of claim 46 wherein the low-refractive-index film comprises a fluoropolymer.
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48. The device of claim 2 wherein the angle of the taper is substantially constant.
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49. The device of claim 2 wherein the angle of the taper is greater on the end of said portion that is closest to the first waveguide section than on the end of said portion that is farthest from the first waveguide section.
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50. The device of claim 2 wherein the angle of the taper is less than one degree in at least some portion of the tapered portion.
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51. The device of claim 2 wherein the angle of the taper is greater than zero degrees and less than 0.25 degrees in at least some portion of the tapered portion.
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52. The device of claim 2 wherein the first waveguide section comprises at least one single mode optical fiber.
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53. The device of claim 2 wherein light propagates substantially from the end of the second waveguide section farthest from the optical filter to the end of the second waveguide section closest to the optical filter.
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54. The device of claim 2 wherein light propagates substantially from the end of the second waveguide section closest to the optical filter to the end of the second waveguide section farthest from the optical filter.
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55. The device of claim 2, further comprising a layer of opaque material applied to the second waveguide section.
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56. The device of claim 2 wherein the first waveguide section and second waveguide section are fused together.
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57. The device of claim 2 wherein the second waveguide section is a modified region of a waveguide of which the first waveguide section is a part.
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58. The device of claim 2 wherein the first waveguide section and second waveguide section are separate optical components that are in optical communication.
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59. The device of claim 2 wherein the second waveguide section comprises fused silica.
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60. The device of claim 2 wherein the first waveguide section comprises at least one single mode optical fiber.
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61. The device of claim 1 wherein at least a portion of the second waveguide section comprises material of varying refractive index.
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62. The device of claim 61 wherein the material of varying refractive index is incorporated into the portion of the second waveguide section that is closest to the end of the first waveguide section.
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63. The device of claim 62 wherein the refractive index of the material of varying refractive index increases as distance from the end of the first waveguide section increases.
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64. The device of claim 61 wherein the refractive index of the material of varying refractive index decreases with radial distance from the longitudinal axis of the portion of the second waveguide section.
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65. A method for designing a second waveguide section of a waveguide device for filtering light comprising an optical filter, a first section of waveguide, and the second section of waveguide, the second section of waveguide positioned between the first section of waveguide and the optical filter, the diameter of the second section of waveguide being greater on the end adjacent to the optical filter than on the end opposite the optical filter, comprising the steps of
selecting a hypothetical physical configuration of the second waveguide section to be evaluated, selecting a plurality of hypothetical light rays having different angular orientations that enter the second waveguide section from the end of the second waveguide section that is farthest from the optical filter, tracing the paths of the plurality of hypothetical light rays through the hypothetical physical configuration of the second waveguide section, calculating the spectral and directional characteristics of the light rays that will pass through the optical filter after having entered the second waveguide section from the end of the second waveguide section that is farthest from the optical filter and traversing the second waveguide section, selecting a second hypothetical physical configuration of the second waveguide section to be evaluated, tracing the paths of the plurality of hypothetical light rays through the second hypothetical physical configuration of the second waveguide section, calculating the spectral and directional characteristics of the light rays that will pass through the optical filter after having entered the second waveguide section from the end of the second waveguide section that is farthest from the optical filter and traversing the second waveguide section, and comparing the results of the evaluations and selecting a configuration of the device that produces acceptable results.
Specification