Method and apparatus for controlling multiple-wavelength-pumped raman amplifier and computer product

• US 20060001950A1
• Filed: 08/29/2005
• Published: 01/05/2006
• Est. Priority Date: 02/27/2003
• Status: Active Grant

• Current Assignee: Molex LLC (KOCH Industries Incorporated)
• Original Assignee: Furukawa Electric Company Limited
• Inventors: Nakajima, Takeshi, Sakano, Misao, Fujimura, Koji, Namiki, Shu
• Granted Patent: US 7,262,903 B2
• Time in Patent Office: Days
• US Class Current: 359/334
• CPC Class Codes: H01S 2301/04 Gain spectral shaping, flattening
• CPC Class Codes: H01S 3/06725 Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06758 Tandem amplifiers
• CPC Class Codes: H01S 3/06766 C-band amplifiers, i.e. amplification in the range of about 1530 nm to 1560 nm
• CPC Class Codes: H01S 3/0677 L-band amplifiers, i.e. amplification in the range of about 1560 nm to 1610 nm
• CPC Class Codes: H01S 3/094003 the pumped medium being a fibre
• CPC Class Codes: H01S 3/094011 with bidirectional pumping, i.e. with injection of the pump light from both two ends of the fibre
• CPC Class Codes: H01S 3/094096 Multi-wavelength pumping
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 3/1305 Feedback control systems
• CPC Class Codes: H01S 3/302 in an optical fibre
• CPC Class Codes: H04B 10/2916 using Raman or Brillouin amplifiers

Abstract

A multiple-wavelength-pumped Raman amplifier includes a control unit that controls, based on a relational expression associating an amount of fluctuation in a current signal light power at a signal input end, an amount of fluctuation in a current pumping light power at a pumping light input end, an amount of fluctuation in the current signal power at a signal output end, and an amount of fluctuation in the current pumping light power at a pumping light output end, two fluctuation amounts by determining other two fluctuation amounts in advance, to determine pumping light powers satisfying the relational expression.

Claims

1. A multiple-wavelength-pumped Raman amplifier that sets and controls arbitrary signal gain and output characteristics for a wavelength-multiplexed signal light, the multiple-wavelength-pumped Raman amplifier comprising a control unit that controls, based on a relational expression associating a first fluctuation amount, a second fluctuation amount, a third fluctuation amount, and a fourth fluctuation amount, two fluctuation amounts from among the first to the fourth fluctuation amounts by determining other two fluctuation amounts in advance, to determine pumping light powers satisfying the relational expression, wherein

the first fluctuation amount is an amount of fluctuation in a current signal light power at a signal input end,

the second fluctuation amount is an amount of fluctuation in a current pumping light power at a pumping light input end,

the third fluctuation amount is an amount of fluctuation in the current signal power at a signal output end, and

the fourth fluctuation amount is an amount of fluctuation in the current pumping light power at a pumping light output end.

2. The multiple-wavelength-pumped Raman amplifier according to claim 1, wherein the relational expression is a simultaneous linear equation.

3. The multiple-wavelength-pumped Raman amplifier according to claim 1, wherein the relational expression is a linear approximation formula obtained by eliminating quadratic terms from a nonlinear propagation equation described with an amount of fluctuation in power.

4. The multiple-wavelength-pumped Raman amplifier according to claim 1, wherein the relational expression is an approximation in section obtained by assuming distribution information of a fixed length in an optical fiber under consideration as a constant.

5. The multiple-wavelength-pumped Raman amplifier according to claim 2, wherein a coefficient matrix of the simultaneous linear equation includes parameters of an optical fiber that serves as an amplification medium as a matrix element.

6. The multiple-wavelength-pumped Raman amplifier according to claim 5, wherein the parameters of the optical fiber are a loss parameter and a Raman gain parameter.

7. The multiple-wavelength-pumped Raman amplifier according to claim 2, wherein a coefficient matrix of the simultaneous linear equation includes a longitudinal distribution of at least one of signal power and pumping power currently obtained as a matrix element.

8. The multiple-wavelength-pumped Raman amplifier according to claim 7, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is obtained by solving a nonlinear propagation equation.

9. The multiple-wavelength-pumped Raman amplifier according to claim 7, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is obtained by performing a measurement of a power distribution in the optical fiber.

10. The multiple-wavelength-pumped Raman amplifier according to claim 9, wherein the measurement is performed by optical time domain reflectometry.

11. The multiple-wavelength-pumped Raman amplifier according to claim 7, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is stored as data in a predetermined table in advance.

12. The multiple-wavelength-pumped Raman amplifier according to claim 7, wherein the matrix element is obtained by performing a measurement in advance.

13. The multiple-wavelength-pumped Raman amplifier according to claim 12, wherein

the measurement is performed by sequentially changing pumping powers one by one and measuring an amount of gain fluctuation due to influence of the changing the pumping powers, and

the matrix element is calculated from a result of the measurement.

14. The multiple-wavelength-pumped Raman amplifier according to claim 1, wherein the first fluctuation amount and the third fluctuation amount are determined in advance to calculate the second fluctuation amount and the fourth fluctuation amount.

15. The multiple-wavelength-pumped Raman amplifier according to claim 1, wherein the first fluctuation amount and the second fluctuation amount are determined in advance to calculate the third fluctuation amount and the fourth fluctuation amount.

16. The multiple-wavelength-pumped Raman amplifier according to claim 1, wherein the first fluctuation amount and the third fluctuation amount are determined in advance to calculate the second fluctuation amount and the fourth fluctuation amount.

17. The multiple-wavelength-pumped Raman amplifier according to claim 1, wherein

the control unit performs an intermediate calculation process in which an intermediate value between a value currently obtained and a final target value is set as a provisional target value and the other two fluctuation amounts satisfying the provisional target value, and

the final target value is obtained by repeatedly performing the intermediate calculation process by replacing the value currently obtained with a value calculated by the intermediate calculation process.

18. The multiple-wavelength-pumped Raman amplifier according to claim 17, wherein the control unit updates information on a longitudinal distribution of an optical fiber under consideration when performing the intermediate calculation process.

19. The multiple-wavelength-pumped Raman amplifier according to claim 18, wherein the control unit updates the information on the longitudinal distribution of the optical fiber by adding values of longitudinal distributions of the other two fluctuation amounts currently calculated to a current value of the longitudinal distribution of the optical fiber.

20. The multiple-wavelength-pumped Raman amplifier according to claim 18, wherein the control unit updates the information on the longitudinal distribution of the optical fiber by solving a nonlinear propagation equation.

21. The multiple-wavelength-pumped Raman amplifier according to claim 18, wherein a longitudinal distribution of at least one of signal power and pumping power is obtained by performing a measurement of a power distribution in the optical fiber.

22. The multiple-wavelength-pumped Raman amplifier according to claim 21, wherein the measurement is performed by optical time domain reflectometry.

23. The multiple-wavelength-pumped Raman amplifier according to claim 18, wherein a step size of the provisional target value at the time of the intermediate calculation process is a logarithmic value of a signal light gain.

24. The multiple-wavelength-pumped Raman amplifier according to claim 23, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 0.5 decibel in the signal light gain.

25. The multiple-wavelength-pumped Raman amplifier according to claim 23, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 1 decibel in the signal light gain.

26. The multiple-wavelength-pumped Raman amplifier according to claim 23, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 2 decibels in the signal light gain.

27. The multiple-wavelength-pumped Raman amplifier according to claim 23, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 3 decibels in the signal light gain.

28. The multiple-wavelength-pumped Raman amplifier according to claim 18, wherein a step size of the provisional target value at the time of the intermediate calculation process is different for at least one of each intermediate arithmetic processing and each signal channel.

29. A method of controlling a multiple-wavelength-pumped Raman amplifier that sets and controls arbitrary signal gain and output characteristics for a wavelength-multiplexed signal light, the method comprising controlling, based on a relational expression associating a first fluctuation amount, a second fluctuation amount, a third fluctuation amount, and a fourth fluctuation amount, two fluctuation amounts from among the first to the fourth fluctuation amounts by determining other two fluctuation amounts in advance, to determine pumping light powers satisfying the relational expression, wherein

the first fluctuation amount is an amount of fluctuation in a current signal light power at a signal input end,

the second fluctuation amount is an amount of fluctuation in a current pumping light power at a pumping light input end,

the third fluctuation amount is an amount of fluctuation in the current signal power at a signal output end, and

the fourth fluctuation amount is an amount of fluctuation in the current pumping light power at a pumping light output end.

30. The method according to claim 29, wherein the relational expression is a simultaneous linear equation.

31. The method according to claim 29, wherein the relational expression is a linear approximation formula obtained by eliminating quadratic terms from a nonlinear propagation equation described with an amount of fluctuation in power.

32. The method according to claim 29, wherein the relational expression is an approximation in section obtained by assuming distribution information of a fixed length in an optical fiber under consideration as a constant.

33. The method according to claim 30, wherein a coefficient matrix of the simultaneous linear equation includes parameters of an optical fiber that serves as an amplification medium as a matrix element.

34. The method according to claim 33, wherein the parameters of the optical fiber are a loss parameter and a Raman gain parameter.

35. The method according to claim 30, wherein a coefficient matrix of the simultaneous linear equation includes a longitudinal distribution of at least one of signal power and pumping power currently obtained as a matrix element.

36. The method according to claim 35, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is obtained by solving a nonlinear propagation equation.

37. The method according to claim 35, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is obtained by performing a measurement of a power distribution in the optical fiber.

38. The method according to claim 37, wherein the measurement is performed by optical time domain reflectometry.

39. The method according to claim 35, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is stored as data in a predetermined table in advance.

40. The method according to claim 35, wherein the matrix element is obtained by performing a measurement in advance.

41. The method according to claim 40, wherein

the measurement is performed by sequentially changing pumping powers one by one and measuring an amount of gain fluctuation due to influence of the changing the pumping powers, and

the matrix element is calculated from a result of the measurement.

42. The method according to claim 29, wherein the first fluctuation amount and the third fluctuation amount are determined in advance to calculate the second fluctuation amount and the fourth fluctuation amount.

43. The method according to claim 29, wherein the first fluctuation amount and the second fluctuation amount are determined in advance to calculate the third fluctuation amount and the fourth fluctuation amount.

44. The method according to claim 29, wherein the first fluctuation amount and the third fluctuation amount are determined in advance to calculate the second fluctuation amount and the fourth fluctuation amount.

45. The method according to claim 29, wherein

the controlling includes performing an intermediate calculation process in which an intermediate value between a value currently obtained and a final target value is set as a provisional target value and the other two fluctuation amounts satisfying the provisional target value, and

the final target value is obtained by repeatedly performing the intermediate calculation process by replacing the value currently obtained with a value calculated by the intermediate calculation process.

46. The method according to claim 45, wherein the controlling includes updating information on a longitudinal distribution of an optical fiber under consideration when performing the intermediate calculation process.

47. The method according to claim 46, wherein the updating includes updating the information on the longitudinal distribution of the optical fiber by adding values of longitudinal distributions of the other two fluctuation amounts currently calculated to a current value of the longitudinal distribution of the optical fiber.

48. The method according to claim 46, wherein the updating includes updating the information on the longitudinal distribution of the optical fiber by solving a nonlinear propagation equation.

49. The method according to claim 46, wherein a longitudinal distribution of at least one of signal power and pumping power is obtained by performing a measurement of a power distribution in the optical fiber.

50. The method according to claim 49, wherein the measurement is performed by optical time domain reflectometry.

51. The method according to claim 46, wherein a step size of the provisional target value at the time of the intermediate calculation process is a logarithmic value of a signal light gain.

52. The method according to claim 51, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 0.5 decibel in the signal light gain.

53. The method according to claim 51, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 1 decibel in the signal light gain.

54. The method according to claim 51, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 2 decibels in the signal light gain.

55. The method according to claim 51, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 3 decibels in the signal light gain.

56. The method according to claim 46, wherein a step size of the provisional target value at the time of the intermediate calculation process is different for at least one of each intermediate arithmetic processing and each signal channel.

57. A computer-readable recording medium that stores a program for controlling a multiple-wavelength-pumped Raman amplifier that sets and controls arbitrary signal gain and output characteristics for a wavelength-multiplexed signal light, wherein the program causes a computer to execute controlling, based on a relational expression associating a first fluctuation amount, a second fluctuation amount, a third fluctuation amount, and a fourth fluctuation amount, two fluctuation amounts from among the first to the fourth fluctuation amounts by determining other two fluctuation amounts in advance, to determine pumping light powers satisfying the relational expression, wherein

the first fluctuation amount is an amount of fluctuation in a current signal light power at a signal input end,

the second fluctuation amount is an amount of fluctuation in a current pumping light power at a pumping light input end,

the third fluctuation amount is an amount of fluctuation in the current signal power at a signal output end, and

the fourth fluctuation amount is an amount of fluctuation in the current pumping light power at a pumping light output end.

58. The computer-readable recording medium according to claim 57, wherein the relational expression is a simultaneous linear equation.

59. The computer-readable recording medium according to claim 57, wherein the relational expression is a linear approximation formula obtained by eliminating quadratic terms from a nonlinear propagation equation described with an amount of fluctuation in power.

60. The computer-readable recording medium according to claim 57, wherein the relational expression is an approximation in section obtained by assuming distribution information of a fixed length in an optical fiber under consideration as a constant.

61. The computer-readable recording medium according to claim 58, wherein a coefficient matrix of the simultaneous linear equation includes parameters of an optical fiber that serves as an amplification medium as a matrix element.

62. The computer-readable recording medium according to claim 61, wherein the parameters of the optical fiber are a loss parameter and a Raman gain parameter.

63. The computer-readable recording medium according to claim 58, wherein a coefficient matrix of the simultaneous linear equation includes a longitudinal distribution of at least one of signal power and pumping power currently obtained as a matrix element.

64. The computer-readable recording medium according to claim 63, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is obtained by solving a nonlinear propagation equation.

65. The computer-readable recording medium according to claim 63, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is obtained by performing a measurement of a power distribution in the optical fiber.

66. The computer-readable recording medium according to claim 65, wherein the measurement is performed by optical time domain reflectometry.

67. The computer-readable recording medium according to claim 63, wherein the longitudinal distribution of the at least one of the signal power and the pumping power is stored as data in a predetermined table in advance.

68. The computer-readable recording medium according to claim 63, wherein the matrix element is obtained by performing a measurement in advance.

69. The computer-readable recording medium according to claim 68, wherein

the measurement is performed by sequentially changing pumping powers one by one and measuring an amount of gain fluctuation due to influence of the changing the pumping powers, and

the matrix element is calculated from a result of the measurement.

70. The computer-readable recording medium according to claim 57, wherein the first fluctuation amount and the third fluctuation amount are determined in advance to calculate the second fluctuation amount and the fourth fluctuation amount.

71. The computer-readable recording medium according to claim 57, wherein the first fluctuation amount and the second fluctuation amount are determined in advance to calculate the third fluctuation amount and the fourth fluctuation amount.

72. The computer-readable recording medium according to claim 57, wherein the first fluctuation amount and the third fluctuation amount are determined in advance to calculate the second fluctuation amount and the fourth fluctuation amount.

73. The computer-readable recording medium according to claim 57, wherein

the controlling includes performing an intermediate calculation process in which an intermediate value between a value currently obtained and a final target value is set as a provisional target value and the other two fluctuation amounts satisfying the provisional target value, and

the final target value is obtained by repeatedly performing the intermediate calculation process by replacing the value currently obtained with a value calculated by the intermediate calculation process.

74. The computer-readable recording medium according to claim 73, wherein the controlling includes updating information on a longitudinal distribution of an optical fiber under consideration when performing the intermediate calculation process.

75. The computer-readable recording medium according to claim 74, wherein the updating includes updating the information on the longitudinal distribution of the optical fiber by adding values of longitudinal distributions of the other two fluctuation amounts currently calculated to a current value of the longitudinal distribution of the optical fiber.

76. The computer-readable recording medium according to claim 74, wherein the updating includes updating the information on the longitudinal distribution of the optical fiber by solving a nonlinear propagation equation.

77. The computer-readable recording medium according to claim 74, wherein a longitudinal distribution of at least one of signal power and pumping power is obtained by performing a measurement of a power distribution in the optical fiber.

78. The computer-readable recording medium according to claim 77, wherein the measurement is performed by optical time domain reflectometry.

79. The computer-readable recording medium according to claim 74, wherein a step size of the provisional target value at the time of the intermediate calculation process is a logarithmic value of a signal light gain.

80. The computer-readable recording medium according to claim 79, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 0.5 decibel in the signal light gain.

81. The computer-readable recording medium according to claim 79, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 1 decibel in the signal light gain.

82. The computer-readable recording medium according to claim 79, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 2 decibels in the signal light gain.

83. The computer-readable recording medium according to claim 79, wherein the step size of the provisional target value at the time of the intermediate calculation process is equal to or less than 3 decibels in the signal light gain.

84. The computer-readable recording medium according to claim 74, wherein a step size of the provisional target value at the time of the intermediate calculation process is different for at least one of each intermediate arithmetic processing and each signal channel.

85. An apparatus for controlling pumping light powers for a multiple-wavelength-pumped Raman amplifier that is pumped by pumping lights from a plurality of pumping light sources, by measuring gain wavelength characteristic or signal-power wavelength characteristic of the multiple-wavelength-pumped Raman amplifier using a plurality of photodetectors having different wavelength-sensitivity characteristics, the apparatus comprising a determining unit that estimates a power of each of signal channels in a wavelength band for use based on values monitored by the photodetectors, and determines the pumping light powers using the power of each of the signal channels estimated.

86. The apparatus according to claim 85, wherein number of the photodetectors is equal to or less than number of the signal channels.

87. The apparatus according to claim 85, wherein number of the photodetectors is equal to or less than number of the pumping lights.

88. The apparatus according to claim 85, wherein each of the photodetectors has a filter for transmitting a light of a predetermined band.

89. The apparatus according to claim 85, further comprising a wavelength selecting unit that selects a wavelength of a light, wherein

each of the photodetectors receives a light of a wavelength selected by the wavelength selecting unit.

90. The apparatus according to claim 89, wherein the wavelength selecting unit is an arrayed waveguide grating.

91. The apparatus according to claim 89, wherein the wavelength selecting unit is a fiber-type coupler.

92. The apparatus according to claim 85, wherein the determining unit estimates the power of each of the signal channels by performing an interpolation of the values monitored by the photodetectors.

93. The apparatus according to claim 92, wherein the interpolation is a linear interpolation.

94. The apparatus according to claim 92, wherein the interpolation is performed by superposing a wavelength-dependent Raman gain of each of the pumping lights.

95. The apparatus according to claim 92, wherein the interpolation is performed by converting the values monitored by the photodetectors into a power of a representative wavelength that is different for each of the photodetectors.

96. The apparatus according to claim 95, wherein the interpolation is a linear interpolation of the power of the representative wavelength.

97. The apparatus according to claim 95, wherein the interpolation is performed by superposing a wavelength-dependent Raman gain of each of the pumping lights.

98. The apparatus according to claim 92, wherein the interpolation is processed such that

99. The apparatus according to claim 98, wherein the interpolation is processed such that

100. A method of controlling pumping light powers for a multiple-wavelength-pumped Raman amplifier that is pumped by pumping lights from a plurality of pumping light sources, by measuring gain wavelength characteristic or signal-power wavelength characteristic of the multiple-wavelength-pumped Raman amplifier using a plurality of photodetectors having different wavelength-sensitivity characteristics, the method comprising:

estimating a power of each of signal channels in a wavelength band for use based on values monitored by the photodetectors; and

determining the pumping light powers using the power of each of the signal channels estimated.

101. The method according to claim 100, wherein the values monitored by the photodetectors are measured by number of the photodetectors that is equal to or less than number of the signal channels.

102. The method according to claim 100, wherein the values monitored by the photodetectors are measured by number of the photodetectors is equal to or less than number of the pumping lights.

103. The method according to claim 100, wherein each of the values monitored by the photodetectors is a value obtained by filtering a light of a predetermined wavelength band.

104. The method according to claim 100, wherein each of the values monitored by the photodetectors is a value corresponding to a light of a wavelength selected by a wavelength selecting unit.

105. The method according to claim 100, wherein the estimating includes estimating the power of each of the signal channels by performing an interpolation of the values monitored by the photodetectors.

106. The method according to claim 105, wherein the interpolation is a linear interpolation.

107. The method according to claim 105, wherein the interpolation is performed by superposing a wavelength-dependent Raman gain of each of the pumping lights.

108. The method according to claim 105, wherein the interpolation is performed by converting the values monitored by the photodetectors into a power of a representative wavelength that is different for each of the photodetectors.

109. The method according to claim 108, wherein the interpolation is a linear interpolation of the power of the representative wavelength.

110. The method according to claim 108, wherein the interpolation is performed by superposing a wavelength-dependent Raman gain of each of the pumping lights.

111. The method according to claim 105, wherein the interpolation is processed such that

112. The method according to claim 111, wherein the interpolation is processed such that

113. A method of measuring gain wavelength characteristic or signal-power wavelength characteristic of a multiple-wavelength-pumped Raman amplifier that is pumped by pumping lights from a plurality of pumping light sources based on values monitored by a plurality of photodetectors having different wavelength-sensitivity characteristics, the method comprising calculating the gain wavelength characteristic or the signal-power wavelength characteristic from the wavelength-sensitivity characteristics of the photodetectors and gain wavelength characteristics obtained by Raman amplification by the pumping light sources.

114. The method according to claim 113, wherein the values monitored by the photodetectors are measured by number of the photodetectors that is equal to or less than number of the signal channels.

115. The method according to claim 113, wherein the values monitored by the photodetectors are measured by number of the photodetectors is equal to or less than number of the pumping lights.

116. The method according to claim 113, wherein each of the values monitored by the photodetectors is a value obtained by filtering a light of a predetermined wavelength band.

117. The method according to claim 113, wherein each of the values monitored by the photodetectors is a value corresponding to a light of a wavelength selected by a wavelength selecting unit.

118. The method according to claim 113, wherein the calculating includes performing a process such that

119. The method according to claim 118, wherein the process is performed such that

120. A computer readable recording medium that stores a program for controlling pumping light powers for a multiple-wavelength-pumped Raman amplifier that is pumped by pumping lights from a plurality of pumping light sources, by measuring gain wavelength characteristic or signal-power wavelength characteristic of the multiple-wavelength-pumped Raman amplifier using a plurality of photodetectors having different wavelength-sensitivity characteristics, wherein the program causes a computer to execute

estimating a power of each of signal channels in a wavelength band for use based on values monitored by the photodetectors;

and

determining the pumping light powers using the power of each of the signal channels estimated.

121. The computer readable recording medium according to claim 120, wherein the values monitored by the photodetectors are measured by number of the photodetectors that is equal to or less than number of the signal channels.

122. The computer readable recording medium according to claim 120, wherein the values monitored by the photodetectors are measured by number of the photodetectors is equal to or less than number of the pumping lights.

123. The computer readable recording medium according to claim 120, wherein each of the values monitored by the photodetectors is a value obtained by filtering a light of a predetermined wavelength band.

124. The computer readable recording medium according to claim 120, wherein each of the values monitored by the photodetectors is a value corresponding to a light of a wavelength selected by a wavelength selecting unit.

125. The computer readable recording medium according to claim 120, wherein the estimating includes estimating the power of each of the signal channels by performing an interpolation of the values monitored by the photodetectors.

126. The computer readable recording medium according to claim 125, wherein the interpolation is a linear interpolation.

127. The computer readable recording medium according to claim 125, wherein the interpolation is performed by superposing a wavelength-dependent Raman gain of each of the pumping lights.

128. The computer readable recording medium according to claim 125, wherein the interpolation is performed by converting the values monitored by the photodetectors into a power of a representative wavelength that is different for each of the photodetectors.

129. The computer readable recording medium according to claim 128, wherein the interpolation is a linear interpolation of the power of the representative wavelength.

130. The computer readable recording medium according to claim 128, wherein the interpolation is performed by superposing a wavelength-dependent Raman gain of each of the pumping lights.

131. The computer readable recording medium according to claim 125, wherein the interpolation is processed such that

132. The computer readable recording medium according to claim 131, wherein the interpolation is processed such that

133. A computer readable recording medium that stores a program for measuring gain wavelength characteristic or signal-power wavelength characteristic of a multiple-wavelength-pumped Raman amplifier that is pumped by pumping lights from a plurality of pumping light sources based on values monitored by a plurality of photodetectors having different wavelength-sensitivity characteristics, wherein the program causes a computer to execute calculating the gain wavelength characteristic or the signal-power wavelength characteristic from the wavelength-sensitivity characteristics of the photodetectors and gain wavelength characteristics obtained by Raman amplification by the pumping light sources.

134. The computer readable recording medium according to claim 133, wherein the values monitored by the photodetectors are measured by number of the photodetectors that is equal to or less than number of the signal channels.

135. The computer readable recording medium according to claim 133, wherein the values monitored by the photodetectors are measured by number of the photodetectors is equal to or less than number of the pumping lights.

136. The computer readable recording medium according to claim 133, wherein each of the values monitored by the photodetectors is a value obtained by filtering a light of a predetermined wavelength band.

137. The computer readable recording medium according to claim 133, wherein each of the values monitored by the photodetectors is a value corresponding to a light of a wavelength selected by a wavelength selecting unit.

138. The computer readable recording medium according to claim 133, wherein the calculating includes performing a process such that

139. The computer readable recording medium according to claim 138, wherein the process is performed such that