Apparatus and method for optical gain fiber having segments of differing core sizes
First Claim
1. A method comprising:
- providing a plurality of amplifying fiber segments including a first amplifying segment and a second amplifying segment, wherein the first amplifying segment has a core that has a first diameter, wherein the core of the first amplifying segment is surrounded by an inner cladding that is surrounded by an outer cladding, wherein the second amplifying segment has a core that has a second diameter, wherein the core of the second amplifying segment is surrounded by an inner cladding that is surrounded by an outer cladding, and wherein the first diameter is less than the second diameter;
providing a connecting fiber segment, the connecting fiber segment having a core that includes a minimum-diameter core portion that has a third diameter, wherein the core of the connecting fiber segment is surrounded by a first cladding, and wherein the third diameter is less than the first diameter;
fusing one end of the connecting fiber segment to an end of the first amplifying segment and fusing an opposite end of the connecting fiber segment to an end of the second amplifying segment,coupling pump light into the core of the first amplifying segment;
coupling pump light into the core of the second amplifying segment;
coupling signal light from the core of the first amplifying segment into the core of the connecting fiber segment and coupling signal light from the core of the connecting fiber segment into the core of the second amplifying segment; and
amplifying the signal light in the first amplifying segment and in the second amplifying segment.
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Abstract
Apparatus and method for amplifying laser signals using segments of fibers of differing core diameters and/or differing cladding diameters to suppress amplified spontaneous emission and non-linear effects such as four-wave mixing (FWM), self-phase modulation, and stimulated Brillouin and/or Raman scattering (SBS/SRS). In some embodiments, different core sizes have different sideband spacings (spacing between the desired signal and wavelength-shifted lobes). Changing core sizes and providing phase mismatches prevent buildup of non-linear effects. Some embodiments further include a bandpass filter to remove signal other than the desired signal wavelength and/or a time gate to remove signal at times other than during the desired signal pulse. Some embodiments include photonic-crystal structures to define the core for the signal and/or the inner cladding for the pump. Some embodiments include an inner glass cladding to confine the signal in the core and an outer glass cladding to confine pump light in the inner cladding.
233 Citations
20 Claims
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1. A method comprising:
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providing a plurality of amplifying fiber segments including a first amplifying segment and a second amplifying segment, wherein the first amplifying segment has a core that has a first diameter, wherein the core of the first amplifying segment is surrounded by an inner cladding that is surrounded by an outer cladding, wherein the second amplifying segment has a core that has a second diameter, wherein the core of the second amplifying segment is surrounded by an inner cladding that is surrounded by an outer cladding, and wherein the first diameter is less than the second diameter; providing a connecting fiber segment, the connecting fiber segment having a core that includes a minimum-diameter core portion that has a third diameter, wherein the core of the connecting fiber segment is surrounded by a first cladding, and wherein the third diameter is less than the first diameter; fusing one end of the connecting fiber segment to an end of the first amplifying segment and fusing an opposite end of the connecting fiber segment to an end of the second amplifying segment, coupling pump light into the core of the first amplifying segment; coupling pump light into the core of the second amplifying segment; coupling signal light from the core of the first amplifying segment into the core of the connecting fiber segment and coupling signal light from the core of the connecting fiber segment into the core of the second amplifying segment; and amplifying the signal light in the first amplifying segment and in the second amplifying segment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus comprising:
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an optical-fiber amplifier having a plurality of optically coupled fiber segments including a first amplifier segment and a second amplifier segment, wherein the first segment has a core that has a first diameter, wherein the core of the first amplifier segment is surrounded by an inner cladding and the inner cladding is surrounded by an outer cladding, wherein the second amplifier segment has a core that has a second diameter, wherein the core of the second amplifier segment is surrounded by an inner cladding and the inner cladding is surrounded by an outer cladding, and wherein the first diameter is less than the second diameter; a connector fiber segment, the connector fiber segment having a core that includes a minimum-diameter core portion that has a third diameter, wherein the core of the connector fiber segment is surrounded by a first cladding, wherein the connector fiber segment is between and fused to both the second amplifier segment and the first amplifier segment, and wherein the third diameter is less than the first diameter; one or more pump-light sources, wherein pump light from the one or more pump-light sources is coupled into the core of the first amplifier segment and into the core of the second amplifier segment; and a signal-light source, wherein signal light from the signal-light source is coupled into the core of the first amplifier segment, wherein amplified signal light from the core of the first amplifier segment is coupled into the core of the connector fiber segment, and wherein signal light from the core of the connecting segment is coupled into the core of the second amplifier segment. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. An apparatus comprising:
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a plurality of amplifying fiber segments including a first amplifying segment and a second amplifying segment, wherein the first segment has a core that has a first diameter, wherein the core of the first amplifying segment is surrounded by an inner cladding and the inner cladding is surrounded by an outer cladding, wherein the second amplifying segment has a core that has a second diameter, wherein the core of the second amplifying segment is surrounded by an inner cladding and the inner cladding is surrounded by an outer cladding, and wherein the first diameter is less than the second diameter; one or more pump-light sources operatively coupled to provide pump light into the core of the first amplifying segment and into the core of the second amplifying segment; and curved-fiber means for coupling signal light from the core of the first amplifying segment into the core of the second amplifying segment, wherein the curved-fiber means for coupling signal conducts signal light through a cross-sectional area having a third diameter that is smaller than the first diameter and smaller than the second diameter. - View Dependent Claims (19, 20)
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Specification