Active optical fiber and method for fabricating an active optical fiber
First Claim
1. A section of active optical fiber comprisinga core with a first index of refraction, said core being active,an inner cladding layer with a second index of refraction for propagating pump radiation, said second index of refraction being smaller than said first index of refraction andan outer cladding layer with a third index of refraction around said inner cladding layer, said third index of refraction being smaller than said second index of refraction,wherein the diameter of said core and the thickness of said inner cladding change gradually along the length of said section of active optical fiber forming a tapered longitudinal profile enabling a continuous mode conversion process along the length of the section of fiber and the tapered core supporting multimode operation at the thicker end of the section of fiber, wherein said tapered longitudinal profile of said section of active optical fiber is selected from a group of profiles including a power law profile, an exponential profile and a combination of these profiles.
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Abstract
A section of active optical fiber (11) which comprises an active core (1), an inner cladding layer (2) and an outer cladding layer (3). The diameter of said core 1) and the thickness of said inner cladding (2) change gradually along the length of said section of active optical fiber (11). This forms tapered longitudinal profile enabling a continuous mode conversion process along the length of the section of fiber (11). The method for fabricating a section of tapered active optical fiber comprises the steps of fabricating a preform for drawing active optical fiber from said preform, installing said preform into a drawing tower, drawing optical fiber in said drawing tower and altering at least one of the two parameters including the take-off preform speed and the take-up fiber speed during drawing of the optical fiber.
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Citations
13 Claims
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1. A section of active optical fiber comprising
a core with a first index of refraction, said core being active, an inner cladding layer with a second index of refraction for propagating pump radiation, said second index of refraction being smaller than said first index of refraction and an outer cladding layer with a third index of refraction around said inner cladding layer, said third index of refraction being smaller than said second index of refraction, wherein the diameter of said core and the thickness of said inner cladding change gradually along the length of said section of active optical fiber forming a tapered longitudinal profile enabling a continuous mode conversion process along the length of the section of fiber and the tapered core supporting multimode operation at the thicker end of the section of fiber, wherein said tapered longitudinal profile of said section of active optical fiber is selected from a group of profiles including a power law profile, an exponential profile and a combination of these profiles.
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8. A method for fabricating a section of active optical fiber, said method comprising
fabricating a preform for drawing active optical fiber from said preform in a drawing tower, installing said preform into a drawing tower, drawing optical fiber in said drawing tower and altering at least one of the two parameters including the take-off preform speed and the take-up fiber speed during drawing of the optical fiber to synthesize a tapered longitudinal profile for said section of active optical fiber, wherein said tapered longitudinal profile of said section of active optical fiber is selected from a group of profiles including a power law profile, an exponential profile and a combination of these profiles.
Specification