Chirped period gratings for raman amplification in circulator loop cavities
First Claim
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1. A circulator loop cavity, comprising:
- an optical circulator having a first port, a second port and a third port;
a gain medium connected between said second port and said third port for producing gain to an optical signal therein;
a coupler that couples a pump beam to said gain medium to pump said gain medium; and
a plurality of gratings coupled to the second port that provide cavity wavelength control.
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Abstract
The present invention provides a structure for Raman amplification of signals with counter-propagation of signal and pump and wavelength control while permitting broad bandwidth within each Raman order. The broadband optical amplifier of the invention combines Raman amplification with a circulator loop cavity and/or chirped Bragg gratings to achieve bandwidth performance improvements. The beneficial properties of the circulator loop cavity and/or chirped Bragg gratings can also combined with noise dampening property of the Sagnac Raman cavity.
236 Citations
80 Claims
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1. A circulator loop cavity, comprising:
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an optical circulator having a first port, a second port and a third port;
a gain medium connected between said second port and said third port for producing gain to an optical signal therein;
a coupler that couples a pump beam to said gain medium to pump said gain medium; and
a plurality of gratings coupled to the second port that provide cavity wavelength control. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A circulator loop cavity amplifier comprising:
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an input port for introducing an optical signal to be amplified;
a circulator loop cavity including;
an optical circulator having a first port, a second port and a third port; and
a gain medium connected between said first port and said third port for producing gain to said optical signal therein;
a Sagnac Raman loop mirror comprising an amplifying fiber having its two ends connected to a coupler;
a coupler for coupling a pump beam to said gain medium to pump said gain medium; and
an output port for outputting said optical signal from said gain medium, wherein said optical signal travels in a first direction along said gain medium, and said pump light travels along said gain medium in a direction opposite to said first direction. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A circulator loop cavity, comprising:
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an optical circulator having a first port, a second port and a third port;
a gain medium connected between said first port and said third port for producing gain to an optical signal therein;
a coupler for coupling a pump beam to said gain medium to pump said gain medium; and
a broadband reflector connected to said second port for providing cavity wavelength control. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A circulator loop cavity amplifier, comprising:
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a first optical circulator having a first port, a second port and a third port;
a first gain medium connected to said second port of said circulator;
a second gain medium connected to said first gain medium at a joint;
a means for connecting said second gain medium to said third port of said circulator;
means for introducing and removing an optical signal at said joint such that said optical signal travels in sequence through said first gain medium, said second port, said third port, said connecting means, and said second gain medium;
an optical connection between said connecting means and said first port of said circulator; and
a coupling means connected to said first port of said circulator for coupling a pump beam to pump said first and second gain mediums, wherein said pump beam travels in sequence through said first port, said second port, said first gain medium, said second gain medium, said connecting means, and said optical connection. - View Dependent Claims (32, 33, 34, 35, 36, 37)
a second optical circulator having a first port connected to said connecting means and a third port connected to said first port of said first circulator; and
a plurality of chirped Bragg gratings connected to a second port of said second circulator, each of said chirped Bragg grating being used for one cascade Raman order.
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36. The circulator loop cavity amplifier according to claim 35, wherein said chirped Bragg grating has a uniform period.
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37. The circulator loop cavity amplifier according to claim 35, wherein said chirped Bragg grating has a step-wise period.
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38. A Sagnac Raman cavity, comprising:
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a Sagnac loop mirror comprising a Raman gain medium and a coupler connected thereto, said Raman gain medium producing gain to an optical signal therein;
a plurality of chirped Bragg gratings, each of said chirped Bragg grating being used for one cascade Raman order; and
a coupling means for coupling a pump beam to said Raman gain medium to pump said Raman gain medium. - View Dependent Claims (39, 40, 41, 42, 43, 44)
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45. A linear Raman cavity, comprising:
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a plurality of chirped Bragg gratings;
a broadband reflector for reflecting at least two cascade Raman orders;
a Raman gain medium positioned therebetween for producing gain to an optical signal therein, each of said chirped Bragg grating being used for one cascade Raman order; and
a coupling means for coupling a pump beam to said Raman gain medium to pump said Raman gain medium. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. A linear Raman cavity oscillator, comprising:
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a group of gratings;
a broadband reflector for reflecting at least two cascade Raman orders;
a Raman gain medium positioned therebetween to form a cavity for producing gain to an optical signal through cascade Raman amplification, wherein each of said gratings is used for one cascade Raman order; and
a coupling means located outside said cavity for coupling a pump beam to pump said Raman gain medium and outputting said optical signal. - View Dependent Claims (56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70)
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71. A linear Raman cavity oscillator, comprising:
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a multi-stack dielectric mirror having a plurality of dielectric layers;
a broadband reflector;
a Raman gain medium positioned therebetween to form a cavity for producing gain to an optical signal through cascade Raman amplification, wherein each of said dielectric layer reflects at one cascade Raman order;
a coupling means located inside said cavity for coupling a pump beam to pump said Raman gain medium; and
an output port for outputting said optical signal. - View Dependent Claims (72, 73)
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74. A multiple-output-wavelength Raman oscillator, comprising:
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an oscillator cavity having a Raman gain medium therein; and
output couplers at one end of said cavity formed by a plurality of gratings, each of said gratings having a reflectivity less than 98%, characterized in that;
the reflectivities of said output couplers are chosen such that said cavity oscillation thresholds are reached with an increasing pump power in an order of grating center wavelength with the shortest wavelength reaching threshold first and the longest wavelength reaching threshold last; and
an optical frequency difference between a grating with the shortest center wavelength and a grating with the longest wavelength is less than an optical frequency difference between an Raman pump source and the peak of the Raman gain for said Raman pump source in said Raman gain medium. - View Dependent Claims (75, 76, 77, 78)
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79. A linear Raman cavity oscillator, comprising:
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a plurality of gratings;
a broadband reflector for substantially reflecting at least two cascade Raman orders;
a Raman gain medium positioned therebetween to form an optical cavity and produce gain in an optical signal; and
a coupler for coupling a pump beam to pump said Raman gain medium;
wherein said coupler couples the pump beam to pump said Raman gain medium and outputs said optical signal.
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80. A linear Raman cavity oscillator, comprising:
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a plurality of gratings;
a broadband reflector for substantially reflecting at least two cascade Raman orders;
a Raman gain medium positioned therebetween to form an optical cavity and produce gain in an optical signal; and
a coupler for coupling a pump beam to pump said Raman gain medium;
wherein said coupler is a wavelength division multiplexing coupler that couples the pump beam to pump said Raman gain medium and outputs said optical signal.
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Specification