Waveguide Retroreflector And Method Of Fabricating The Same
First Claim
1. A waveguide retroreflector, comprising:
- an optical waveguide having an end face;
an optical element bonded to said optical waveguide end face,wherein the optical element is substantially free of voids and/or air spaces in a light transmitting region thereof, wherein said light transmitting region of the optical element has a length along a direction of light propagation in said region;
wherein the optical element has a convex end face having a radius of curvature at an end of the light transmitting region;
wherein said radius of curvature is between 80% and 120% of the length of the light transmitting region of the optical element, such that at least 5% of a light reflected from said convex end face is coupled back into the optical waveguide.
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Abstract
A waveguide retroreflector consists of an end cap with curved output surface attached to a waveguide such as optical fiber. The radius of curvature of the output surface of the end cap matches the length of the end cap so as to retro-reflect a substantial portion of radiation exiting the waveguide, back into the waveguide. A method of fabricating the waveguide retroreflector includes steps of splicing an end cap to a waveguide, heating the free flat surface of the end cap, so that surface tension changes the shape of the end cap to a convex shape due to surface tension, monitoring amount of light reflected off the surface being heated, and stopping applying the heat when the amount of the reflected light approaches a maximum value.
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Citations
25 Claims
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1. A waveguide retroreflector, comprising:
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an optical waveguide having an end face; an optical element bonded to said optical waveguide end face, wherein the optical element is substantially free of voids and/or air spaces in a light transmitting region thereof, wherein said light transmitting region of the optical element has a length along a direction of light propagation in said region; wherein the optical element has a convex end face having a radius of curvature at an end of the light transmitting region; wherein said radius of curvature is between 80% and 120% of the length of the light transmitting region of the optical element, such that at least 5% of a light reflected from said convex end face is coupled back into the optical waveguide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for fabricating a waveguide retroreflector, comprising:
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a) providing an end cap affixed to an optical waveguide, wherein said end cap contains substantially homogeneous material, wherein said end cap has a length between two first and second opposing and substantially flat end faces, and wherein the first end face is fused to an end of said waveguide; b) irradiating a second end of the waveguide with light such that the light is transmitted by the waveguide into the end cap; c) measuring a fraction of said light reflected from the second end face of the end cap and coupled back into the waveguide; d) applying sufficient amount of heat to said second end face, so that surface tension changes the shape of the flat second end face so as to form a convex shaped end having a radius of curvature; e) repeating steps c) and d) until the radius of curvature of said convex shape becomes between 80% and 120% of the length of the end cap;
wherein proximity of said radius of curvature to said length of the end cap is determined from the value of said fraction of light, compared to a maximum value of said fraction of light. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A fiber laser resonator cavity, comprising:
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an optical waveguide, having;
first, an active section, and second, an end face;an optical element bonded to said end face of the optical waveguide; wherein the optical element is substantially free of voids and/or air spaces in a light transmitting region thereof; wherein the optical element has an end face located at an end of the light transmitting region; wherein said end face of the optical element is shaped to be perpendicular to the ray fan of a light emitted by the active section of the optical waveguide, said light impinging onto the end face of the optical element after having passed through the light transmitting region thereof.
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Specification