Fiber optic amplifier
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorsHerbert J. Shaw, Marvin Chodorow
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Abstract
A pair of small diameter optical fibers are arranged in a side-by-side configuration, the first fiber providing a pumping source, and the second fiber doped with a material which will lase at the signal frequency. The signal to be amplified propagates through the second fiber to stimulate emission of coherent light from the lasing material, resulting in amplification of the signal. The refractive index of the first and second fibers are selected such that the signal in the second fiber is well guided, while the pumping light in the first fiber is unguided, yielding low losses in the second fiber but high transfer of the pumping light from the first fiber to the second fiber.
Claims30
A fiber optic device for producing coherent light, comprising:
- a first fiber having a first refractive index;
- a second fiber, formed of material which will lase, having a second refractive index higher than said first refractive index;
- means for introducing light into said first fiber for pumping said material of said second fiber, the wavelength of said light for pumping selected to cause a population inversion in said material which will lase;
- and
- an intermediate transfer material for allowing the transfer of light from said first fiber to said second fiber while preventing transfer of light from said second fiber to said first fiber, said transfer material having an index of refraction which is less than said second fiber, but which is not less than said first fiber.
A fiber optic amplifier, comprising:
- first and second optical fibers positioned in close relative proximity at an interaction region;
- a transparent jacket having an index of refraction N3 and surrounding said first and second optical fibers at said interaction region;
- said first optical fiber formed of material which will lase, having an index of refraction N1, and transmitting a signal to be amplified;
- said second optical fiber having an index of refraction N2, and transmitting light for pumping said material which will lase;
- and
- said indexes of refraction related by:
- N2<N3<N1 (a) to enable said first fiber to guide said signal to be amplified at said interaction region, but (b) to prohibit said second fiber from guiding said light for pumping at said interaction region.
A method of pumping a doped optical lasing fiber, comprising:
- positioning said fiber in side-by-side relationship with a pumping fiber at an interaction region;
- providing a transparent jacket which surrounds said lasing fiber and said pumping fiber at said interaction region;
- providing pumping illumination in said pumping fiber;
- and
- selecting the indices of refraction of said fibers and said jacket (a) to cause said lasing fiber to guide light produced when said doped optical lasing fiber lases but (b) to prohibit said pumping fiber from guiding said pumping illumination at said interaction region so that said pumping illumination is coupled to said lasing fiber at said interaction region.
Apparatus for generating coherent light in an optical fiber, comprising:
- a first fiber formed of material which will lase, having a first refractive index;
- a second fiber, having a second refractive index, said fibers having respective two-dimensional mating surfaces which are juxtaposed with each other in abutting relationship along a selected length of said fibers to form an interaction region;
- and
- a source of pumping illumination coupled to said second fiber, said second refractive index of said second fiber lower than said first refractive index of said first fiber to cause said pumping illumination to transfer from said second fiber through said surfaces and into said first fiber at said selected length of said fibers to cause inversion of said material which will lase.
A methd of generating coherent light, comprising:
- providing a first fiber, formed of a material which will lase, having a first refractive index, said first fiber having a two-dimensional mating surface;
- providing a second fiber having a second refractive index, said second fiber having a two-dimensional mating surface;
- juxtaposing the mating surfaces of said fibers to form an interaction region;
- coupling a source of pumping illumination to said second fiber;
- and
- selecting said indices of refraction of said fibers so that said second index is lower than said first index to cause said pumping illumination to transfer from said second fiber to said first fiber for absorption by said first fiber.
Dependencies are inferred from the claim text.