Microlenses for coupling optical fibers to elliptical light beams
First Claim
1. A process for fabricating an optical fiber microlens for coupling an optical power between an optical device having an asymmetric output light distribution and an optical fiber, the ellipticity ratio of the asymmetric modal area of the device being greater than 1.5:
- 1.0, which comprises;
laser micromachining an end portion of an optical fiber by ablating and heating the material of the end portion of the optical fiber by means of a laser beam, in whichsaid micromachining is conducted by removing a greater proportion of the material at opposite ends of one orthogonal axis of the optical fiber than at opposite ends of the other orthogonal axis, such as to produce a microlens having a given ellipticity ratio.
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Abstract
An asymmetric hyperbolic microlens on the end of a single-mode optical fiber enhances the fiber'"'"'s coupling to elliptical laser beams. The lenses, with controlled eccentricity ratios, are made by micromachining the end of the fiber with a pulsed CO2 laser as the fiber is directed, preferably by computer control, about the focused laser beam. Coupling efficiencies of 90 percent (-0.75 dB) have been realized with single transverse mode lasers at a wavelength of 0.98 μm having an approximately 3 to 1 beam ellipicity. With multimode lasers at 1.48 μm having similar elliptical beams, the asymmetric lenses demonstrate an almost 2 dB increase in coupling efficiency over symmetric hyperbolic microlenses. Such lasers are useful to pump erbium-doped fiber amplifiers. About 120 mw was coupled from such a laser into single-mode fiber.
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Citations
16 Claims
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1. A process for fabricating an optical fiber microlens for coupling an optical power between an optical device having an asymmetric output light distribution and an optical fiber, the ellipticity ratio of the asymmetric modal area of the device being greater than 1.5:
- 1.0, which comprises;
laser micromachining an end portion of an optical fiber by ablating and heating the material of the end portion of the optical fiber by means of a laser beam, in which said micromachining is conducted by removing a greater proportion of the material at opposite ends of one orthogonal axis of the optical fiber than at opposite ends of the other orthogonal axis, such as to produce a microlens having a given ellipticity ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- 1.0, which comprises;
Specification