SNR booster for WDM systems

US 6,760,509 B2
Filed: 02/14/2001
Issued: 07/06/2004
Est. Priority Date: 02/14/2000
Status: Expired due to Term

First Claim

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1. A non-linear optical loop mirror for processing optical signals, comprising:

an optical fiber with a signal input and a signal output, at least a portion of the optical fiber being a dispersion compensating fiber and at least a portion of the optical fiber forming a loop, the dispersion compensating fiber having an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the optical signals;

a bi-directional amplifier coupled to the optical fiber; and

a coupler coupled to a fist portion of the optical fiber and a second portion of the optical fiber to form a fiber loop.

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Abstract

A non-linear optical loop mirror for processing optical signals comprises an optical fiber, a bi-directional amplifier, and a coupler. The optical fiber has a signal input and a signal output. At least a portion of the optical fiber includes a dispersion compensating fiber. At least a portion of the optical fiber forms a loop. The dispersion compensating fiber has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the optical signals. The bi-directional amplifier is coupled to the optical fiber. The coupler is coupled to a first portion of the optical fiber and a second portion of the optical fiber to form a fiber loop.

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221 Claims

1. A non-linear optical loop mirror for processing optical signals, comprising:
- an optical fiber with a signal input and a signal output, at least a portion of the optical fiber being a dispersion compensating fiber and at least a portion of the optical fiber forming a loop, the dispersion compensating fiber having an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the optical signals;
  
  a bi-directional amplifier coupled to the optical fiber; and
  
  a coupler coupled to a fist portion of the optical fiber and a second portion of the optical fiber to form a fiber loop.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- - 2. The mirror of claim 1, wherein the coupler splits a power of the optical signals with a first portion of the optical signals traveling in a first direction in the fiber loop and a second portion of optical signals traveling in a counter-propagating direction in the fiber loop.
  - 3. The mirror of claim 1, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 20 ps/nm-km for a majority of wavelengths in the optical signals.
  - 4. The mirror of claim 1, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the optical signals.
  - 5. The mirror of claim 1, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 6. The mirror of claim 1, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 7. The mirror of claim 2, wherein the coupler provides substantially equal coupling in the two directions.
  - 8. The mirror of claim 2, further comprising:
9. The mirror of claim 1, further comprising:
- a lossy element coupled to the fiber loop.
10. The mirror of claim 9, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
11. The mirror of claim 1, wherein the fiber loop has a first end and a second end and the bi-directional amplifier is positioned closer to one of the first and second ends.
12. The mirror of claim 1, wherein the bi-directional amplifier is a rare earth doped amplifier.
13. The mirror of claim 1, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
14. The mirror of claim 1, wherein the bi-directional amplifier is a Raman amplifier.
15. The mirror of claim 1, wherein the dispersion compensating fiber has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
16. The mirror of claim 15, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
17. The mirror of claim 1, wherein the fiber loop includes at least eight walk-off lengths.
18. The mirror of claim 1, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
19. The mirror of claim 1, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
20. The mirror of claim 1, wherein the bi-directional amplifier provides a gain to at least some of the optical signals of at least 10 dB.

21. A non-linear optical loop mirror for processing optical signals, comprising:
- a first optical fiber with a signal input and a signal output, a second optical fiber coupled to the first optical fiber to form a fiber loop, at least a portion of the second optical fiber being a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the optical signals;
  
  a bi-directional amplifier coupled to at least one of the first and second optical fibers; and
  
  a coupler coupled to the first and second optical fiber.
- View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
- - 22. The mirror of claim 21, wherein the coupler splits a power of an optical signal with a first portion traveling in a first direction in the fiber loop and a second portion traveling in a counter-propagating direction in the fiber loop.
  - 23. The mirror of claim 21, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 20 ps/nm-km for a majority of wavelengths in the signal.
  - 24. The mirror of claim 21, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the signal.
  - 25. The mirror of claim 21, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 26. The mirror of claim 21, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 27. The mirror of claim 22, wherein the coupler provides substantially equal coupling in the two directions.
  - 28. The mirror of claim 22, further comprising:
29. The mirror of claim 21, further comprising:
- a lossy element coupled to the fiber loop.
30. The mirror of claim 29, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
31. The mirror of claim 21, wherein the fiber loop has a first end and a second end, wherein the bi-directional amplifier is positioned closer to one of the first and second ends.
32. The mirror of claim 21, wherein the bi-directional amplifier is a rare earth doped amplifier.
33. The mirror of claim 21, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
34. The mirror of claim 21, wherein the bi-directional amplifier is a Raman amplifier.
35. The mirror of claim 21, wherein the dispersion compensating fiber has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
36. The mirror of claim 35, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
37. The mirror of claim 21, wherein the fiber loop includes at least eight walk-off lengths.
38. The mirror of claim 21, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
39. The mirror of claim 21, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
40. The mirror of claim 21, wherein the bi-directional amplifier provides a gain to the optical signals of at least 10 dB.

41. A method of processing optical signals, comprising:
- providing a non-linear optical loop mirror that includes a dispersion compensating fiber and a fiber loop, the dispersion compensating fiber having an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the optical signals;
  
  introducing the optical signal to the non-linear optical loop mirror;
  
  simultaneously amplifying and dispersion compensating the optical signal in the non-linear optical loop mirror.
- View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
- - 42. The method of claim 41, further comprising:
43. The method of claim 41, further comprising:
- splitting a power of an optical signal in the non-linear optical mirror with a first portion traveling in a first direction in the fiber loop and a second portion traveling in a counter-propagating direction in the fiber loop.
44. The method of claim 41, wherein at least a majority of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the signal.
45. The method of claim 41, further comprising:
- wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the optical signal.
46. The method of claim 43, further comprising:
- providing substantially equal coupling of the first and second portion in the two directions.
47. The method of claim 43, further comprising:
- aligning polarizations of the optical signal of the two directions when recombined in the fiber loop.
48. The method of claim 41, further comprising:
- wherein the dispersion compensating fiber has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
49. The method of claim 48, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
50. The method of claim 41, wherein the fiber loop includes at least eight walk-off lengths.
51. The method of claim 41, further comprising:
- providing gain to the optical signal of at least 10 dB.

52. A non-linear optical loop mirror for processing optical signals, comprising:
- an optical fiber with a signal input, a signal output and a fiber loop, at least a portion of the optical fiber having a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals, at least a portion of the optical fiber forming a fiber loop;
  
  a bi-directional amplifier coupled to the optical fiber; and
  
  a coupler coupled to the fiber loop.
- View Dependent Claims (53, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71)
- - 53. The mirror of claim 52, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
    - of a phase shift from self phase modulation of one of the adjacent wavelengths.
  - 62. The mirror of claim 52, further comprising:
63. The mirror of claim 62, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
64. The mirror of claim 52, wherein the fiber loop has a first end and a second end, wherein the bi-directional amplifier is positioned closer to one of the first and second ends.
65. The mirror of claim 52, wherein the bi-directional amplifier is a rare earth doped amplifier.
66. The mirror of claim 52, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
67. The mirror of claim 52, wherein the bi-directional amplifier is a Raman amplifier.
68. The mirror of claim 52, wherein the fiber loop includes at least eight walk-off lengths.
69. The mirror of claim 52, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
70. The mirror of claim 52, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
71. The mirror of claim 52, wherein the mirror provides a bi-directional amplifier gain of at least 10 dB.

54. An optical regeneration system, comprising:
- a wavelength demultiplexer;
  
  a wavelength multiplexer;
  
  a plurality of nonlinear optical loop mirrors, each comprising;
  
  a first fiber comprising a first end, a second end, and a first effective nonlinearity determined at least by an index of refraction of the first fiber and an effective area of the first fiber;
  
  a second fiber comprising a first end, a second end, and a second effective nonlinearity determined at least by an index of refraction of the second fiber and an effective area of the second fiber, wherein the first effective nonlinearity is distinct from the second effective nonlinearity, and at least a portion of one or both of the first fiber and the second fiber form a fiber loop; and
  
  a coupler coupled to the first end of the first fiber, the first end of the second fiber, the wavelength demultiplexer, and the wavelength multiplexer; and
  
  a first bi-directional amplifier coupled to the second end of the first fiber and the second end of the second fiber, and amplifying at least signals traveling in a first direction from the second end of the first fiber to the second end of the second fiber and signals traveling in a second direction from the second end of the second fiber to the second end of the first fiber.
- View Dependent Claims (55, 56, 57, 58, 59, 60, 61)
- - 55. The optical regeneration system of claim 54, wherein at least a portion of at least one of the first fiber or the second fiber comprises an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the signal.
  - 56. The optical regeneration system of claim 54, wherein at least a portion of at least one of the first fiber or the second fiber comprises an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the signal.
  - 57. The optical regeneration system of claim 54, wherein at least one of the first fiber or the second fiber comprises a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 58. The optical regeneration system of claim 54, wherein at least one of the first fiber or the second fiber comprises a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 59. The optical regeneration system of claim 54, wherein the coupler splits a power of the optical signals with a first portion of the optical signals traveling in a first direction in the fiber loop and a second portion of optical signals traveling in a counter-propagating direction in the fiber loop.
  - 60. The optical regeneration system of claim 59, wherein the coupler provides substantially equal coupling in the two directions.
  - 61. The optical regeneration system of claim 59, further comprising:

72. An optical system for processing optical signals, comprising:
- an input optical fiber;
  
  a splitter coupled to the input optical fiber and separates adjacent channels of an input optical signal; and
  
  at least a first loop mirror coupled to the splitter, the at least first loop mirror including a fiber loop, at least a portion of the fiber loop including a dispersion compensating fiber, at least a portion of the dispersion compensating fiber having an absolute magnitude of dispersion of 20 ps/nm-km for a majority of wavelengths in the optical signals.
- View Dependent Claims (73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91)
- - 73. The system of claim 72, further comprising:
74. The system of claim 72, further comprising:
- a coupler that splits a power of the optical signals with a first portion of the optical signals traveling in a first direction in the fiber loop and a second portion of optical signals traveling in a counter-propagating direction in the fiber loop.
75. The system of claim 72, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the optical signals.
76. The system of claim 72, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
- 1 km^−
  
  1.
77. The system of claim 72, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
- 1 km^−
  
  1.
78. The system of claim 74, wherein the coupler provides substantially equal coupling in the two directions.
79. The system of claim 74, further comprising:
- a polarization controller coupled to the fiber loop that aligns polarizations of the optical signals of the two directions when the optical signals recombine in the fiber loop.
80. The system of claim 72, further comprising:
- a lossy element coupled to the fiber loop.
81. The system of claim 80, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
82. The system of claim 72, further comprising:
- a bi-directional amplifier positioned closer to one of a first end and a second end of the fiber loop.
83. The system of claim 82, wherein the bi-directional amplifier is a rare earth doped amplifier.
84. The system of claim 82, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
85. The system of claim 82, wherein the bi-directional amplifier is a Raman amplifier.
86. The system of claim 72, wherein the dispersion compensating fiber has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
87. The system of claim 86, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
88. The system of claim 72, wherein the fiber loop includes at least eight walk-off lengths.
89. The system of claim 72, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
90. The system of claim 72, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
91. The system of claim 82, wherein the bi-directional amplifier provides a gain to the optical signals of at least 10 dB.

92. A non-linear optical loop mirror, comprising:
- a first optical fiber with a first effective non-linearity;
  
  a second optical fiber coupled to the first optical fiber and forming a fiber loop, the second optical fiber having a second effective non-linearity that is different from the first effective non-linearity;
  
  a coupler coupled to the first and second optical fibers, and wherein a length of the first optical fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the first fiber.
- View Dependent Claims (93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109)
- - 93. The mirror of claim 92, wherein a length of the second fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the second fiber.
  - 94. The mirror of claim 92, wherein the first effective non-linearity is directly proportional to a non-linear index of refraction of the first optical fiber and inversely proportion to an effective area of the first optical fiber, and the second effective non-linearity is directly proportional to a non-linear index of refraction of the second optical fiber and inversely proportion to an effective area of the second optical fiber.
  - 95. The mirror of claim 92, wherein a difference between the first and second effective non-linearities is greater than 20% of at least one of the first and second effective non-linearities.
  - 96. The mirror of claim 92, wherein the first and second optical fibers have different dispersions.
  - 97. The mirror of claim 92, wherein the coupler splits a power of an optical signal with a first portion traveling in a first direction in the fiber loop and a second portion traveling in a counter-propagating direction in the fiber loop.
  - 98. The mirror of claim 92, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the signal.
  - 99. The mirror of claim 92, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the signal.
  - 100. The mirror of claim 98, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 101. The mirror of claim 98, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 102. The mirror of claim 97, wherein the coupler provides substantially equal coupling in the two directions.
  - 103. The mirror of claim 97, further comprising:
104. The mirror of claim 92, further comprising:
- a lossy element coupled to the fiber loop.
105. The mirror of claim 104, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
106. The mirror of claim 92, wherein at least one of the first and second optical fibers has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
107. The mirror of claim 106, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
108. The mirror of claim 92, wherein the mirror provides simultaneous dispersion compensation and boosting of signal to noise ratio of an optical signal.
109. The mirror of claim 92, wherein at least one of the first and second optical fibers has a length of at least 100 m.

110. A non-linear optical loop mirror, comprising:
- a first optical fiber with a first effective non-linearity;
  
  a second optical fiber coupled to the first optical fiber and forming a fiber loop, the second optical fiber having a second effective non-linearity that is different from the first effective non-linearity;
  
  a bi-directional amplifier coupled to at least one of the first and second optical fibers and positioned substantially at a midpoint of the fiber loop; and
  
  a coupler coupled to the first and second optical fibers.
- View Dependent Claims (111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134)
- - 111. The mirror of claim 110, wherein a length of the first optical fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the first fiber.
  - 112. The mirror of claim 110, wherein a length of the second fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the second fiber.
  - 113. The mirror of claim 110, wherein the first effective non-linearity is directly proportional to a non-linear index of refraction of the first optical fiber and inversely proportion to an effective area of the first optical fiber, and the second effective non-linearity is directly proportional to a non-linear index of refraction of the second optical fiber and inversely proportion to an effective area of the second optical fiber.
  - 114. The mirror of claim 110, wherein a difference between the first and second effective non-linearities is greater than 20% of at least one of the first and second effective non-linearities.
  - 115. The mirror of claim 110, wherein the first and second optical fibers have different dispersions.
  - 116. The mirror of claim 110, wherein the coupler splits a power of an optical signal with a first portion traveling in a first direction in the fiber loop and a second portion traveling in a counter-propagating direction in the fiber loop.
  - 117. The mirror of claim 110, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the signal.
  - 118. The mirror of claim 110, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the signal.
  - 119. The mirror of claim 117, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 120. The mirror of claim 117, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 121. The mirror of claim 116, wherein the coupler provides substantially equal coupling in the two directions.
  - 122. The mirror of claim 116, further comprising:
123. The mirror of claim 110, further comprising:
- a lossy element coupled to the fiber loop.
124. The mirror of claim 123, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
125. The mirror of claim 110, wherein the bi-directional amplifier is coupled to each of the first and second optical fibers.
126. The mirror of claim 110, wherein the bi-directional amplifier is a rare earth doped amplifier.
127. The mirror of claim 110, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
128. The mirror of claim 110, wherein the bi-directional amplifier is a Raman amplifier.
129. The mirror of claim 110, wherein at least one of the first and second optical fibers has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
130. The mirror of claim 129, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
131. The mirror of claim 110, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
132. The mirror of claim 110, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
133. The mirror of claim 110, wherein the bi-directional amplifier provides a gain to the optical signals of at least 10 dB.
134. The mirror of claim 110 wherein at least one of the first and second optical fibers has a length of at least 100 m.

135. An optical system for processing optical signals, comprising:
- an input optical fiber;
  
  a splitter coupled to the input optical fiber and separates adjacent channels of an input optical signal; and
  
  at least a first loop mirror coupled to the splitter, the at least first loop mirror including;
  
  an optical fiber with a signal input and a signal output, at least a portion of the optical fiber being a dispersion compensating fiber and at least a portion of the optical fiber forming a loop, the dispersion compensating fiber having an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the optical signals;
  
  a bi-directional amplifier coupled to the optical fiber; and
  
  a coupler coupled to a first portion of the optical fiber and a second portion of the optical fiber to form a fiber loop.
- View Dependent Claims (136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155)
- - 136. The optical system of claim 135, wherein the coupler splits a power of the optical signals with a first portion of the optical signals traveling in a first direction in the fiber loop and a second portion of optical signals traveling in a counter-propagating direction in the fiber loop.
  - 137. The optical system of claim 135, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 20 ps/nm-km for a majority of wavelengths in the optical signals.
  - 138. The optical system of claim 135, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the optical signals.
  - 139. The optical system of claim 135, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 140. The optical system of claim 135, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 141. The optical system of claim 136, wherein the coupler provides substantially equal coupling in the two directions.
  - 142. The optical system of claim 136, further comprising:
143. The optical system of claim 135, further comprising:
- a lossy element coupled to the fiber loop.
144. The optical system of claim 143, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
145. The optical system of claim 135, wherein the fiber loop has a first end and a second end and the bi-directional amplifier is positioned closer to one of the first and second ends.
146. The optical system of claim 135, wherein the bi-directional amplifier is a rare earth doped amplifier.
147. The optical system of claim 135, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
148. The optical system of claim 135, wherein the bi-directional amplifier is a Raman amplifier.
149. The optical system of claim 135, wherein the dispersion compensating fiber has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
150. The optical system of claim 149, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
151. The optical system of claim 135, wherein the fiber loop includes at least eight walk-off lengths.
152. The optical system of claim 135, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
153. The optical system of claim 135, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
154. The optical system of claim 135, wherein the bi-directional amplifier provides a gain to at least some of the optical signals of at least 10 dB.
155. The optical system of claim 135, further comprising:
- a combiner coupled to the at least first loop mirror; and
  
  at least one output fiber coupled to the combiner.

156. An optical system for processing optical signals, comprising:
- an input optical fiber;
  
  a splitter coupled to the input optical fiber and separates adjacent channels of an input optical signal; and
  
  at least a first loop mirror coupled to the splitter, the at least first loop mirror including;
  
  a first optical fiber with a signal input and a signal output, a second optical fiber coupled to the first optical fiber to form a fiber loop, at least a portion of the second optical fiber being a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the optical signals;
  
  a bi-directional amplifier coupled to at least one of the first and second optical fibers; and
  
  a coupler coupled to the first and second optical fiber.
- View Dependent Claims (157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176)
- - 157. The optical system of claim 156, wherein the coupler splits a power of an optical signal with a first portion traveling in a first direction in the fiber loop and a second portion traveling in a counter-propagating direction in the fiber loop.
  - 158. The optical system of claim 156, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 20 ps/nm-km for a majority of wavelengths in the signal.
  - 159. The optical system of claim 156, wherein at least a portion of the dispersion compensating fiber has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the signal.
  - 160. The optical system of claim 156, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 161. The optical system of claim 156, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 162. The optical system of claim 157, wherein the coupler provides substantially equal coupling in the two directions.
  - 163. The optical system of claim 157, further comprising:
164. The optical system of claim 156, further comprising:
- a lossy element coupled to the fiber loop.
165. The optical system of claim 164, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
166. The optical system of claim 156, wherein the fiber loop has a first end and a second end, wherein the bi-directional amplifier is positioned closer to one of the first and second ends.
167. The optical system of claim 156, wherein the bi-directional amplifier is a rare earth doped amplifier.
168. The optical system of claim 156, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
169. The optical system of claim 156, wherein the bi-directional amplifier is a Raman amplifier.
170. The optical system of claim 156, wherein the dispersion compensating fiber has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
171. The optical system of claim 170, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than ¼
- of a phase shift from self phase modulation of one of the adjacent wavelengths.
172. The optical system of claim 156, wherein the fiber loop includes at least eight walk-off lengths.
173. The optical system of claim 156, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
174. The optical system of claim 156, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
175. The optical system of claim 156, wherein the bi-directional amplifier provides a gain to the optical signals of at least 10 dB.
176. The optical system of claim 156, further comprising:
- a combiner coupled to the at least first loop mirror; and
  
  at least one output fiber coupled to the combiner.

177. An optical system for processing optical signals, comprising:
- an input optical fiber;
  
  a splitter coupled to the input optical fiber and separates adjacent channels of an input optical signal; and
  
  at least a first loop mirror coupled to the splitter, the at least first loop mirror including;
  
  a first optical fiber with a first effective non-linearity;
  
  a second optical fiber coupled to the first optical fiber and forming a fiber loop, the second optical fiber having a second effective non-linearity that is different from the first effective non-linearity;
  
  a coupler coupled to the first and second optical fibers, and wherein a length of the first optical fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the first fiber.
- View Dependent Claims (178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195)
- - 178. The optical system of claim 177, wherein a length of the second fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the second fiber.
  - 179. The optical system of claim 177, wherein the first effective non-linearity is directly proportional to a non-linear index of refraction of the first optical fiber and inversely proportion to an effective area of the first optical fiber, and the second effective non-linearity is directly proportional to a non-linear index of refraction of the second optical fiber and inversely proportion to an effective area of the second optical fiber.
  - 180. The optical system of claim 177, wherein a difference between the first and second effective non-linearities is greater than 20% of at least one of the first and second effective non-linearities.
  - 181. The optical system of claim 177, wherein the first and second optical fibers have different dispersions.
  - 182. The optical system of claim 177, wherein the coupler splits a power of an optical signal with a first portion traveling in a first direction in the fiber loop and a second portion traveling in a counter-propagating direction in the fiber loop.
  - 183. The optical system of claim 177, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the signal.
  - 184. The optical system of claim 177, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the signal.
  - 185. The optical system of claim 183, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 186. The optical system of claim 183, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 187. The optical system of claim 182, wherein the coupler provides substantially equal coupling in the two directions.
  - 188. The optical system of claim 182, further comprising:
189. The optical system of claim 177, further comprising:
- a lossy element coupled to the fiber loop.
190. The optical system of claim 189, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
191. The optical system of claim 177, wherein at least one of the first and second optical fibers has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
192. The optical system of claim 191, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than 14 of a phase shift from self phase modulation of one of the adjacent wavelengths.
193. The optical system of claim 177, wherein the mirror provides simultaneous dispersion compensation and boosting of signal to noise ratio of an optical signal.
194. The optical system of claim 177, wherein at least one of the first and second optical fibers has a length of at least 100 m.
195. The optical system of claim 177, further comprising:
- a combiner coupled to the at least first loop mirror; and
  
  at least one output fiber coupled to the combiner.

196. An optical system for processing optical signals, comprising:
- an input optical fiber;
  
  a splitter coupled to the input optical fiber and separates adjacent channels of an input optical signal; and
  
  at least a first loop mirror coupled to the splitter, the at least first loop mirror including;
  
  a first optical fiber with a first effective non-linearity;
  
  a second optical fiber coupled to the first optical fiber and forming a fiber loop, the second optical fiber having a second effective non-linearity that is different from the first effective non-linearity;
  
  a bi-directional amplifier coupled to at least one of the first and second optical fibers and positioned substantially at a midpoint of the fiber loop; and
  
  a coupler coupled to the first and second optical fibers.
- View Dependent Claims (197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221)
- - 197. The optical system of claim 196, wherein a length of the first optical fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the first fiber.
  - 198. The optical system of claim 196, wherein a length of the second fiber is greater than a walk-off length for at least a portion of adjacent wavelengths propagating in the second fiber.
  - 199. The optical system of claim 196, wherein the first effective non-linearity is directly proportional to a non-linear index of refraction of the first optical fiber and inversely proportion to an effective area of the first optical fiber, and the second effective non-linearity is directly proportional to a non-linear index of refraction of the second optical fiber and inversely proportion to an effective area of the second optical fiber.
  - 200. The optical system of claim 196, wherein a difference between the first and second effective non-linearities is greater than 20% of at least one of the first and second effective non-linearities.
  - 201. The optical system of claim 196, wherein the first and second optical fibers have different dispersions.
  - 202. The optical system of claim 196, wherein the coupler splits a power of an optical signal with a first portion traveling in a first direction in the fiber loop and a second portion traveling in a counter-propagating direction in the fiber loop.
  - 203. The optical system of claim 196, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 20 ps/nm-km for at least a portion of wavelengths in the signal.
  - 204. The optical system of claim 196, wherein at least a portion of one of the first and second optical fibers is a dispersion compensating fiber that has an absolute magnitude of dispersion of at least 50 ps/nm-km for at least a portion of wavelengths in the signal.
  - 205. The optical system of claim 203, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 2 W⁻
    - 1 km^−
      
      1.
  - 206. The optical system of claim 203, wherein the dispersion compensating fiber has a nonlinear coefficient greater than 3 W⁻
    - 1 km^−
      
      1.
  - 207. The optical system of claim 202, wherein the coupler provides substantially equal coupling in the two directions.
  - 208. The optical system of claim 202, further comprising:
209. The optical system of claim 196, further comprising:
- a lossy element coupled to the fiber loop.
210. The optical system of claim 209, wherein the lossy member is selected from the group consisting of an add/drop multiplexer, a gain equalizer and a dispersion compensating element.
211. The optical system of claim 196, wherein the bi-directional amplifier is coupled to each of the first and second optical fibers.
212. The optical system of claim 196, wherein the bi-directional amplifier is a rare earth doped amplifier.
213. The optical system of claim 196, wherein the bi-directional amplifier is an erbium-doped fiber amplifier.
214. The optical system of claim 196, wherein the bi-directional amplifier is a Raman amplifier.
215. The optical system of claim 196, wherein at least one of the first and second optical fibers has a sufficiently large dispersion to minimize phase shift interactions between adjacent wavelength signals of the optical signals.
216. The optical system of claim 215, wherein the phase shift from cross phase modulation between adjacent wavelengths in the optical signals is no more than % of a phase shift from self phase modulation of one of the adjacent wavelengths.
217. The optical system of claim 196, wherein the mirror provides simultaneous amplification and dispersion compensation of an optical signal.
218. The optical system of claim 196, wherein the mirror provides simultaneous amplification, dispersion compensation and boosting of signal to noise ratio of an optical signal.
219. The optical system of claim 196, wherein the bi-directional amplifier provides a gain to the optical signals of at least 10 dB.
220. The optical system of claim 196, wherein at least one of the first and second optical fibers has a length of at least 100 m.
221. The optical system of claim 196, further comprising:
- a combiner coupled to the at least first loop mirror; and
  
  at least one output fiber coupled to the combiner.

Specification

Resources

Litigation Campaign Assessment

Current Assignee
Board of Regents of the University of Michigan (University of Michigan)
Original Assignee
Board of Regents of the University of Michigan (University of Michigan)
Inventors
Islam, Mohammed N.
Primary Examiner(s)
Lee, John D.
Assistant Examiner(s)
STAHL, MICHAEL J

Application Number

US09/784,649
Publication Number

US 20040091204A1
Time in Patent Office

1,238 Days
Field of Search

385/24, 385/123, 385/27, 385/122, 372/6, 372/94, 356/360, 356/361
US Class Current

385/24
CPC Class Codes

H04B 10/2525   using dispersion-compensati...

H04B 10/299   Signal waveform processing,...

H04B 2210/258   treating each wavelength or...

SNR booster for WDM systems

First Claim

5 Assignments

0 Petitions

Accused Products

Abstract

100 Citations

221 Claims

Specification

Use Cases

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SNR booster for WDM systems

First Claim

5 Assignments

Subscription Required

Subscription Required

0 Petitions

Subscription Required

Accused Products

Subscription Required

Abstract

100 Citations

221 Claims

Specification

Subscription Required

Use Cases

Quick Links

Others