JP5211796B2 - Optical amplifier, input light level calculation method, and optical amplifier controller - Google Patents

Description

  The present invention relates to an optical amplification device, an input light level calculation method, and an optical amplifier control device, and more particularly to an optical amplification device, an input light level calculation method, and an optical amplifier control device that include an optical direct amplifier that directly amplifies light.

  In recent years, in backbone optical transmission, there is a growing demand for longer distances along with higher signal speeds and increased capacity by wavelength multiplexing. In the related optical direct amplifier, it is necessary to monitor the level of the input light in order to perform control to keep the gain constant or to perform a shutdown operation to avoid an optical surge or the like when the input light drops. .

  FIG. 8 is a configuration diagram of an example of a related optical amplification device. Referring to the figure, the related optical amplifying apparatus 5 includes a branching coupler 101, a photodiode 102, an input light level detection circuit 103, and an optical amplifier 151.

  Further, the optical amplifying device 5 includes a branching coupler 108, a photodiode 111, and a constant gain control circuit 113.

  The optical amplifier 151 includes an erbium-doped fiber (EDF) 105, a WDM (Wavelength Division Multiplexing) coupler 106, and a pumping light source 107. Hereinafter, an erbium-doped optical fiber is denoted as “EDF”.

  The optical amplifying device 5 is an erbium-doped optical fiber amplifier (EDFA: EDF Amplifier) using an EDF 105 as an example of an optical amplifier 151 and an excitation light source 107 as an excitation light source.

  In the configuration shown in the figure, a part of the input light of the EDF 105 is branched by the branching coupler 101, a part of the branched input light is received by the photodiode 102 and is photoelectrically converted, and input by the input light level detection circuit 103. The light level is monitored.

  In this configuration, since the level of the input light input to the optical amplifier (EDFA) 151 is directly monitored, high-accuracy level monitoring is possible.

  On the other hand, Patent Document 1 discloses an optical amplifying apparatus that estimates an input level from an output level.

  Further, Patent Document 2 discloses an optical amplifying device that uses auxiliary light for gain control of an amplifier.

Japanese Patent No. 3588390 Japanese Patent Laid-Open No. 2003-124881

  In the example of the related optical amplifier shown in FIG. 8, when long-distance transmission is performed, the transmission line loss increases and the input light becomes weak. On the other hand, since it is necessary to separate the input signal with a branch coupler of about 10 dB, a part of the light input to the photodiode 102 is about −50 dBm. This is a current value (about several nA) that is about the same as the dark current of the photodiode 102.

  For this reason, the monitoring accuracy of the input light monitor is deteriorated, and this error amount changes due to individual differences of the photodiodes 102, the ambient temperature, and the like.

  On the other hand, in order to increase the level of the input signal to the photodiode 102, it is conceivable that the branching ratio of the branching coupler 101 is lowered below 10 dB to increase the amount of branching to the monitor side. However, in this case, the input signal level to the EDF 105 is lowered, and the noise figure of the optical amplifier (EDFA) 151 is deteriorated.

  In addition, the optical amplifying device described in Patent Document 1 is not a device that estimates the input level using a probe light source, and therefore the configuration is completely different from the present invention.

  The purpose of the optical amplifying device described in Patent Document 2 relates to the wavelength setting of supervisory control light (there is no equivalent to supervisory control light in the present invention), and is completely different from the objective of the present invention.

  In addition, the optical amplifying device described in Patent Document 2 includes auxiliary light corresponding to the probe light of the present invention. However, this auxiliary light is used only for gain control, and the condition is that the levels of the auxiliary light and the main light are adjusted to the same level. Thus, the optical amplifying device described in Patent Document 2 is completely different from the present invention in its purpose and configuration.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical amplifying device, an input optical level calculation method, and an optical amplifier control device capable of accurately monitoring the input light level without being influenced by dark current even when the input light is weak. It is in.

  In order to solve the above problems, an optical amplifying device according to the present invention combines a probe light source that outputs probe light, an input light level control circuit that drives the probe light source, and the input light and the probe light. A multiplexing unit; an optical amplifier that amplifies the combined light combined by the combining unit; and the combined light amplified by the optical amplifier is branched, and the probe light is separated from a part of the branched combined light Based on the level of the probe light before being multiplexed by the multiplexing unit obtained via the input light level control circuit and the level of the probe light separated by the optical demultiplexer The gain calculation circuit for calculating the gain of the optical amplifier, the combined light branched by the optical demultiplexer and the level of the separated probe light obtained through the gain calculation circuit, and the gain calculation circuit The gain of the optical amplifier Characterized in that it comprises an input light level calculating circuit for calculating the level of the previous input light are multiplexed by the basis the multiplexing section.

  The input light level calculation method according to the present invention includes a combining step of combining the input light and the probe light, an optical amplification step of amplifying the combined light combined in the combining step, and the amplified An optical demultiplexing step for splitting the combined light and separating the probe light from a part of the branched combined light, and a level of the probe light before being combined at the multiplexing step and the optical demultiplexing step. A gain calculating step for calculating a gain of the combined light based on the level of the probe light, and a level of the combined light branched and separated in the optical demultiplexing step, and the gain calculating step. And an input light level calculating step for calculating the level of the input light before being combined in the combining step based on the gain.

  The optical amplifier control apparatus according to the present invention includes a probe light source that outputs probe light, an input light level control circuit that drives the probe light source, and combines the input light and the probe light and inputs the resultant light to the optical amplifier. An optical multiplexing unit for amplifying, an optical multiplexer for branching the combined light amplified by the optical amplifier, and separating the probe light from a part of the branched combined light, and the input light level control circuit A gain calculation circuit for calculating a gain of the optical amplifier based on a level of the probe light before being multiplexed by the multiplexing unit and a level of the probe light separated by the optical multiplexer; and the optical multiplexer Are combined at the multiplexing unit based on the level of the multiplexed light branched by the optical fiber and the separated probe light obtained through the gain calculation circuit and the gain of the optical amplifier calculated by the gain calculation circuit. Previous input Characterized in that it comprises an input light level calculating circuit for calculating the level of.

  According to the present invention, it is possible to obtain an optical amplification device, an input light level calculation method, and an optical amplifier control device capable of monitoring an accurate input light level without being influenced by dark current even when the input light is weak.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  First, a first embodiment of the present invention will be described. FIG. 1 is a configuration diagram of a first embodiment of an optical amplifying device according to the present invention. In the figure, an optical direct amplifier is used as an example of the optical amplifier.

  Note that the present invention can be applied to an optical amplifier that once converts light into electricity and amplifies it as long as it is reconverted into light after amplification.

  Referring to FIG. 1, the optical amplifying apparatus 1 includes a multiplexing unit 11 that combines the input light 51 and the probe light 52, and an optical amplifier 12 that amplifies the combined light 53 combined by the multiplexing unit 11. It is out.

  Further, the optical amplifying apparatus 1 branches the combined light 54 amplified by the optical amplifier 12, one of them is combined light 59, the other is further branched, and one of the branches is electrically converted and output as a combined current 58. Furthermore, an optical demultiplexer 21 that separates the probe light from the other branched light, electrically converts the probe light and outputs it as a probe current 57 is included. The optical demultiplexer 21 has a function of controlling the probe current included in the combined current 58 to be equal to the probe current 57.

  The optical amplifying apparatus 1 further includes a probe light source 26 that outputs the probe light 52, an input light level control circuit 25 that sets a drive current level of the probe light source 26, and a gain calculation circuit 15. Also, the drive current setting information in the input light level control circuit 25 is input to the gain calculation circuit 15.

  Then, the gain calculation circuit 15 calculates the gain of the optical amplifier 12 based on the drive current level of the probe light 52 and the level of the probe current 57 output from the optical demultiplexer 21.

  Further, the optical amplifying apparatus 1 includes the level of the probe current 57 obtained through the combined current 58 branched by the optical demultiplexer 21 and the gain calculation circuit 15, and the gain of the optical amplifier 12 calculated by the gain calculation circuit 15. The input light level calculation circuit 17 for calculating the level of the input light 51 before being combined by the combining unit 11 is included.

  Next, the operation of the first embodiment will be described. FIG. 2 is a flowchart showing the operation of the first embodiment of the optical amplifier according to the present invention.

  Referring to the figure, the multiplexing unit 11 multiplexes the input light 51 and the probe light 52 (step S1).

  Next, the optical amplifier 12 amplifies the combined light 53 (step S2).

  Next, the optical demultiplexer 21 branches the amplified combined light 54 and separates the probe light from a part of the branched combined light (step S3).

  Next, the gain calculation circuit 15 gains the optical amplifier 12 based on the level of the drive current of the probe light 52 before being multiplexed by the multiplexing unit 11 and the level of the probe current 57 separated by the optical demultiplexer 21. Is calculated (step S4).

  Next, the input light level calculation circuit 17 calculates the level of the input light 51 before being combined by the combining unit 11 based on the levels of the combining current 58 and the probe current 57 and the gain of the optical amplifier 12 ( Step S5). Here, the combined current 58 is a current branched and further electrically converted by the optical demultiplexer 21. The probe current 57 is a current obtained from the optical demultiplexer 21 via the gain calculation circuit 15. The gain of the optical amplifier 12 is calculated by the gain calculation circuit 15.

  As described above, the optical amplifying apparatus 1 according to the first embodiment of the present invention calculates the level of the input light 51 based on the combined current 58, the probe current 57, and the gain of the optical amplifier 12. That is, according to the first embodiment of the present invention, since the level of the input light 51 is calculated based on the current obtained by electrically converting the light amplified by the optical amplifier 12, even when the input light 51 is weak. An accurate input light level can be monitored without being affected by the dark current.

  Next, a second embodiment of the present invention will be described. FIG. 3 is a configuration diagram of a second embodiment of the optical amplifying device according to the present invention. In addition, the same number is attached | subjected about the component similar to FIG. 1, and the description is abbreviate | omitted.

  The second embodiment relates to a specific example of the configuration of the optical demultiplexer 21. Referring to FIG. 3, the optical demultiplexer 21 includes a first branch unit 13, a second branch unit 14, a filter 16, and photodiodes 18 and 19.

  The first branching unit 13 branches the combined light 54 amplified by the optical amplifying unit 12 into combined light 55 and 59.

  The second branching unit 14 further branches the combined light 55 branched by the first branching unit 13 into combined light 56 and 71.

  The filter 16 separates the probe light 72 from the combined light 56 branched by the second branching unit 14.

  The photodiode 18 electrically converts the output probe light 72 from the filter 16 and outputs it as a probe current 57. Further, the photodiode 19 electrically converts the combined light 71 branched by the second branch portion 14 and outputs it as a combined current 58.

  Further, the branching ratio of the combined light 55 in the second branching unit 14 is set in advance so that the current corresponding to the probe light output included in the combined current 58 is equal to the probe current 57.

  The gain calculation circuit 15 is obtained from the input light level control circuit 25 and the level of the drive current of the probe light 52 before being multiplexed to the multiplexing unit 11 and obtained through the photodiode 18 separated by the filter 16. Based on the level of the probe current 57, the gain of the optical amplifier 12 is calculated.

  The input light level calculation circuit 17 calculates the level of the input light 51 based on the level of the combined current 58, the level of the probe current 57, and the gain of the optical amplifying unit 12. The combined current 58 is a current obtained by branching at the second branching section 14 and via the photodiode 19. The probe current 57 is a current obtained through the photodiode 18 and the gain calculation circuit 15 after being separated by the filter 16. The gain of the optical amplifying unit 12 is calculated by the gain calculation circuit 15.

  Next, the operation of the second embodiment will be described. FIG. 4 is a flowchart showing the operation of the second embodiment of the optical amplifying apparatus according to the present invention.

  Referring to the figure, the multiplexing unit 11 multiplexes the input light 51 and the probe light 52 (step S11).

  Next, the optical amplifier 12 amplifies the combined light 53 (step S12).

  Next, the first branching unit 13 branches the combined light 54 amplified by the optical amplifier 12 into the combined light 55 and 59 (step S13).

  Next, the second branching unit 14 further branches one of the branched combined lights 55 into the combined lights 56 and 71 (step S14). The other combined light 71 branched by the second branching section 14 is electrically converted by the photodiode 19 and output as a combined current 58.

Next, the filter 16 separates the probe light 72 from the multiplexed light 56 branched by the second branching unit 14, and the photodiode 18 electrically converts the probe light 72 and outputs a probe current 57 (step S15).

  Next, the gain calculation circuit 15 is based on the level of the drive current of the probe light 52 before being multiplexed by the multiplexing unit 11 and the level of the probe current 57 separated by the filter 16 and electrically converted by the photodiode 18. The gain of the optical amplifier 12 is calculated (step S16).

  Next, the input light level calculation circuit 17 calculates the level of the input light 51 based on the level of the combined current 58, the level of the probe current 57, and the gain of the optical amplifying unit 12 (step S17). The combined current 58 is a current obtained by branching at the second branching section 14 and via the photodiode 19. The probe current 57 is a current obtained through the photodiode 18 and the gain calculation circuit 15 after being separated by the filter 16. The gain of the optical amplifying unit 12 is calculated by the gain calculation circuit 15.

  As described above, according to the second embodiment of the present invention, the optical demultiplexer 21 includes the two branch parts 13 and 14, the filter 16, and the photodiodes 18 and 19. The same effect as in the embodiment can be obtained.

  Next, a third embodiment of the present invention will be described. The third embodiment relates to an optical amplifier control apparatus. An example of the configuration of the optical amplifier control device will be described below with reference to FIG.

  The configuration obtained by removing the optical amplifier 12 from the optical amplification device 1 shown in FIG. 1 is an optical amplifier control device. That is, the optical amplifying apparatus 1 shown in FIG. 1 is an apparatus that amplifies light, whereas the optical amplifier control apparatus according to the third embodiment differs in configuration in that it is an apparatus that controls the optical amplifier 12.

  Referring to the figure, the optical amplifier controller combines the input light 51 and the probe light 52 and amplifies the multiplexing part 11 that amplifies and inputs the multiplexed light 54 amplified by the optical amplifier 12. An optical demultiplexer 21 that demultiplexes the multiplexed light 59, the combined current 58, and the probe current 57 is included.

  Further, the optical amplifier control device gains the gain of the optical amplifier 12 based on the level of the drive current of the probe light 52 before being multiplexed by the multiplexing unit 11 and the level of the probe current 57 demultiplexed by the optical demultiplexer 21. The gain calculation circuit 15 is calculated.

  Further, the optical amplifier control device performs the level of the combined current 58 demultiplexed by the optical demultiplexer 21 and the level of the probe current 57 obtained via the gain calculation circuit 15, and the optical amplifier 12 calculated by the gain calculation circuit 15. An input light level calculation circuit 17 that calculates the level of the input light 51 before being combined by the multiplexer 11 based on the gain is included.

  That is, the optical amplifier control apparatus inputs the combined light 53 of the input light 51 and the probe light 52 to the optical amplifier 12, branches the combined light 54 amplified by the optical amplifier 12 into the combined current 58, and the probe current. 57. The optical amplifier control device calculates the level of the input light 51 based on the combined current 58, the probe current 57, and the gain of the optical amplifier 12.

  As described above, according to the third embodiment of the present invention, the level of the input light 51 of the optical amplifier 12 is set using the combined current 58, the probe current 57, and the gain of the optical amplifier 12 in the optical amplifier control device. It is possible to calculate.

  Next, a fourth embodiment of the present invention will be described. FIG. 5 is a configuration diagram of a fourth embodiment of an optical amplifying device according to the present invention.

  Referring to the figure, the optical amplifying apparatus 2 includes a multiplexing coupler 201, a probe light source 202, an optical amplifier (EDFA) 251, and an optical demultiplexer 252.

  Further, the optical amplifying device 2 includes an input light level control circuit 203 and a gain calculation circuit 213.

  Further, the optical amplifying apparatus 2 includes an input light level calculation circuit 214, a main control circuit 215, and a program storage unit 216.

  On the other hand, the optical amplifier (EDFA) 251 includes an erbium-doped optical fiber (EDF) 205, a WDM coupler 206, and a pumping light source 207.

  The optical demultiplexer 252 includes a branch coupler 208, a branch coupler 209, a probe light separation filter 210, and photodiodes 211 and 212.

  The optical amplifying device 2 includes an input terminal 217 on the input side and an output terminal 218 on the output side.

  On the other hand, the program storage unit 216 in FIG. 5 stores programs for causing the computer to execute steps S2, S4 and S5 in FIG. 2 and steps S12, S16 and S17 in FIG. The “computer” corresponds to the main control circuit 215 of FIG.

  The main control circuit 215 causes the optical amplifier 251 to amplify the multiplexed light 53 in steps S2 and S12 according to the program stored in the program storage unit 216. The main control circuit 215 causes the gain calculation circuit 213 to calculate the gain of the optical amplifier (EDFA) 251 in steps S4 and S16. The main control circuit 215 causes the input light level calculation circuit 214 to calculate the level of the input light 51 in steps S5 and S17.

  The optical amplifying apparatus 2 includes a probe light source 202 for measuring the gain of the EDF 205 on the input side of an optical amplifier (EDFA) 251.

  The input light level control circuit 203 sets the drive current level of the probe light source 202. The set level is notified to the gain calculation circuit 213.

  Further, the optical amplifying apparatus 2 further branches a branch coupler 208 that branches the combined light 54 to the output side of the optical amplifier (EDFA) 251 and one of the combined lights branched by the branch coupler 208 (the combined light 55). A branch coupler 209.

  Then, the optical amplifying apparatus 2 separates the probe light 61 by inputting one of the combined lights branched by the branch coupler 209 (the combined light 56) to the probe light separation filter 210. The probe light 61 is electrically converted into a probe current 57 by the photodiode 212. The probe current 57 is monitored by the gain calculation circuit 213.

  The optical amplifying apparatus 2 calculates the gain of the optical amplifier (EDFA) 251 by causing the gain calculation circuit 213 to monitor the probe current 57. Further, the gain calculation circuit 213 performs not only calculation of gain but also control for making the current output to the pumping light source 207 constant and making the gain of the optical amplifier 251 (EDFA) constant.

  Further, the optical amplifying device 2 causes the photodiode 211 to monitor the level of the other combined light 62 (including all components of the light) branched by the branch coupler 209. That is, the photodiode 211 electrically converts the combined light 62 and outputs a combined current 58.

  The branching ratio of the combined light 55 in the branch coupler 209 is set in advance so that the current corresponding to the probe light output included in the combined current 58 is equal to the probe current 57.

  With this configuration, the level of all components of light (the combined current 58), the level of the probe current 57 obtained via the gain calculation circuit 213, and the gain of the optical amplifier (EDFA) 251 obtained from the gain calculation circuit 213 Therefore, the input light level calculation circuit 214 can calculate the level of the input light, and even when the input light is weak, it is possible to monitor the accurate input light level that is not affected by the dark current.

  Next, the configuration of the optical amplification device 2 will be described in detail. The optical amplifying device 2 includes an optical amplifier (EDFA) 251. The optical amplifier (EDFA) 251 includes an EDF 205, an excitation light source 207 that excites the EDF 205, and a WDM coupler 206.

  Further, the optical amplifying apparatus 2 combines the probe light source 202 for measuring the gain of the optical amplifier (EDFA) 251 and the probe light 52 of the probe light source 202 with the input light 51 and inputs the combined light 53 into the EDF 205. And a multiplexing coupler 201.

  The optical amplifying apparatus 2 further includes a branch coupler 208 that branches the multiplexed light 54 amplified by the optical amplifier (EDFA) 251 and a branch coupler 209 that further branches the multiplexed light 55 branched by the branch coupler 208.

  The optical amplifying apparatus 2 further includes a photodiode 211 that receives the combined light 62 branched by the branch coupler 209 and performs photoelectric conversion.

  Further, the optical amplifying apparatus 2 electrically converts the probe light separation filter 210 that transmits only the wavelength component of the probe light 61 from the combined light 56 branched by the branch coupler 209 and the separated probe light 61, thereby obtaining a probe current 57. And a photodiode 212 that outputs as follows.

  The excitation light source 207 of the optical amplifier (EDFA) 251 optically converts the input current from the gain calculation circuit 213 and outputs it to the WDM coupler 206.

  The gain calculation circuit 213 inputs a predetermined drive current to the excitation light source 207. The gain calculation circuit 213 calculates the gain of the optical amplifier (EDFA) 251 from the level of the probe current 57 electrically converted by the photodiode 212 and the level of the probe light 52 input to the EDF 205. The above “from the level of the probe light 52 input to the EDF 205” is precisely “from the level of the drive current obtained from the probe light source 202 via the input light level control circuit 203”. Further, the gain calculation circuit 213 controls the pumping light source 207 so that the gain of the optical amplifier (EDFA) 251 is constant.

  The input light level calculation circuit 214 subtracts the level of the probe current 57 from the level of the combined current 58 detected by the photodiode 211, and the subtraction result is the gain of the optical amplifier (EDFA) 251 obtained by the gain calculation circuit 213. Based on the above, the level of the input light 51 before being multiplexed by the multiplexing coupler 201 is calculated.

  Next, the operation of the optical amplifying device 2 will be described. The optical amplifying apparatus 2 includes a probe light source 202 for measuring the gain of an optical amplifier (EDFA) 251.

  The probe light 52 of the probe light source 202 is combined with the input light 51 by the combining coupler 201 and the combined light 53 is input to the EDF 205. A part of the combined light 54 amplified by the optical amplifier (EDFA) 251 is branched by the branch coupler 208 to obtain the combined light 55. Further, the combined light 55 is branched by the branch coupler 209 to obtain the combined light 56. Then, the combined light 56 is input to the probe light separation filter 210 to separate the wavelength component of the probe light 61. Then, the probe light 61 is received by the photodiode 212.

  The gain calculation circuit 213 calculates the gain of the optical amplifier (EDFA) 251 based on the ratio between the drive current level of the probe light source 202 and the output level of the probe current 57 electrically converted by the photodiode 212. The drive current level of the probe light source 202 is the current level obtained through the input light level control circuit 203 (that is, the level of the probe light 52 input to the optical amplifier (EDFA) 251). Further, the output level of the probe current 57 electrically converted by the photodiode 212 is the level of the probe light output from the optical amplifier (EDFA) 251. Further, the gain calculation circuit 213 controls the excitation light source 207 so that the gain of the optical amplifier (EDFA) 251 is constant.

  On the other hand, it is possible to obtain the combined current 58 amplified by the optical amplifier (EDFA) 251 by receiving the other combined light 62 branched by the branch coupler 209 by the photodiode 211. That is, since the level of the combined current 58 is much higher than the level of the dark current of the photodiode 211, it is possible to calculate the input light level with high accuracy without being affected by the dark current.

  That is, in the fourth embodiment, the inputs to the photodiodes 211 and 212 are the combined light 62 and the probe light 61 amplified by the optical amplifier (EDFA) 251. Therefore, the photodiodes 211 and 212 monitor light at a level much higher than the dark current (for example, 100 times or more of the dark current). For this reason, in the fourth embodiment, it is possible to monitor the input light with higher accuracy than the method of directly monitoring a part of the input light by the photodiode 102 as in the optical amplifying device 5 shown in FIG.

  Also, unlike the related art in which a part of the input light to the optical amplifying device 5 shown in FIG. 8 is branched to monitor the input light, in the fourth embodiment, all of the input light 51 is sent to the optical amplifier (EDFA) 251. Since it can be input, it is possible to overcome the disadvantage of the related art that the noise figure of the optical amplifier decreases due to the decrease in input.

  As described above, according to the fourth embodiment of the present invention, the weak input light is not directly monitored, but the gain of the optical amplifier (EDFA) 251 is calculated and amplified using the probe light. The input light level is converted by measuring the probe current 57 and the combined current 58 on the output side.

  For this reason, in the fourth embodiment, the current monitored by the photodiodes 211 and 212 is 100 times or more of the dark current, which enables calculation of input light with high accuracy without being affected by the dark current.

  Further, in the fourth embodiment, since the loss of the signal line of the combining coupler 201 in the input unit is suppressed to a low level, it is possible to monitor the input light with high accuracy without degrading the noise figure of the optical amplifier (EDFA) 251. Become.

  Next, a fifth embodiment of the present invention will be described. FIG. 6 is a configuration diagram of a fifth embodiment of an optical amplifying device according to the present invention.

  Referring to the figure, the optical amplifying apparatus 3 includes a multiplexing coupler 301, a probe light source 302, an optical amplifier (EDFA) 351, and an optical demultiplexer 352.

  Further, the optical amplifying device 3 includes an input light level conversion circuit 303, an input light level constant control circuit 304, and a gain calculation circuit 313.

  Further, the optical amplifying device 3 includes an input light level calculation circuit 314, a main control circuit 317, and a program storage unit 318.

  On the other hand, the optical amplifier (EDFA) 351 includes an erbium-doped optical fiber (EDF) 305, a WDM coupler 306, and a pumping light source 307.

  The optical demultiplexer 352 includes a branch coupler 308, a branch coupler 309, a probe light separation filter 310, and photodiodes 311 and 312.

  The optical amplifier 3 includes an input terminal 319 on the input side and an output terminal 320 on the output side.

  Further, in addition to the fourth embodiment shown in FIG. 5, the optical amplifying device 3 branches a part of the output light of the probe light source 302 arranged in the input unit by the branch coupler 315 and receives it by the photodiode 316. The input light level conversion circuit 303 monitors the current conversion value of the probe light.

  Further, the constant input light level control circuit 304 controls the drive current of the probe light source 302 so that the probe light level becomes constant. The current monitored by the input light level conversion circuit 303 is input to the gain calculation circuit 313.

  The program storage unit 318 stores a program similar to the program storage unit 216 shown in FIG. The main control circuit 317 controls the optical amplifier 351, the gain calculation circuit 313, and the input optical level calculation circuit 314 according to the program stored in the program storage unit 318. Note that the control content of the main control circuit 317 is the same as that of the main control circuit 215 (see FIG. 5), and thus the description thereof is omitted here.

  As described above, in the fifth embodiment of the present invention, a part of the output light of the probe light source 302 is branched by the branch coupler 315 and the branched probe light is electrically converted via the photodiode 316. Then, the level of the probe current after electrical conversion is monitored by the input light level conversion circuit 303. Furthermore, the level of the monitored probe current is made constant by the input light level constant control circuit 304. Therefore, according to the fifth embodiment, since a part of the output probe light is monitored and the gain is calculated based on the monitored output probe light, the gain is calculated based on the input current to the probe light source. As compared with the fourth embodiment (see FIG. 5) for calculating the gain, it is possible to calculate the gain with higher accuracy.

  Next, a sixth embodiment of the present invention will be described. FIG. 7 is a configuration diagram of a sixth embodiment of an optical amplifying device according to the present invention.

  Referring to the figure, the optical amplifying device 4 includes a multiplexing coupler 401, a probe light source 402, an optical amplifier (EDFA) 451, and an optical demultiplexer 452.

  Further, the optical amplifying device 4 includes an input light level conversion circuit 403, an input light level constant control circuit 404, and a gain calculation circuit 413.

  Furthermore, the optical amplifying device 4 includes an input light level calculation circuit 414, a main control circuit 418, and a program storage unit 419.

  On the other hand, the optical amplifier (EDFA) 451 includes an erbium-doped optical fiber (EDF) 405, a WDM coupler 406, and a pumping light source 407.

  The optical demultiplexer 452 includes a branch coupler 408, a branch coupler 409, a probe light separation filter 410, and photodiodes 411 and 412.

  The optical amplifying device 4 includes an input terminal 420 on the input side and an output terminal 421 on the output side, and further includes a branch coupler 415, a photodiode 416, and an input light level conversion circuit 403 similar to those of the fifth embodiment. And an input light level constant control circuit 404.

  Further, in order to reduce the influence of spontaneous emission light that can cause an error, the optical amplifying device 4 calculates the level of spontaneous emission light from the gain of the optical amplifier (EDFA) 451 and the total output light level monitored by the photodiode 411. An emission light calculation circuit 417 is included.

  The input light level calculation circuit 414 subtracts the level of the amplified probe current obtained from the photodiode 412 via the gain calculation circuit 413 from the amplified input current detected by the photodiode 411. Then, the subtraction result is calculated backward based on the gain of the optical amplifier (EDFA) 451 obtained by the gain calculation circuit 413 to calculate the level of the input light before being combined by the multiplexing coupler 401.

  Further, the input light level calculation circuit 414 corrects the level of spontaneous emission light with reference to the information from the spontaneous emission light calculation circuit 417.

  As an example, the spontaneous emission light calculation circuit 417 is provided with a table for measuring the relationship between the gain of the optical amplifier (EDFA) 451, the total output light level monitored by the photodiode 411, and the spontaneous emission light level. That is, the spontaneous emission light calculating circuit 417 selects the level of the combined current from the photodiode 411 and the spontaneous emission level (more precisely, the spontaneous emission current level) with respect to the gain of the optical amplifier (EDFA) 451 from the table, and selects the input light. Output to the level calculation circuit 414.

  Further, the spontaneous emission light calculation circuit 417 outputs the combined current from the photodiode 411 to the input light level calculation circuit 414. The input light level calculation circuit 414 subtracts the spontaneous emission light obtained by the spontaneous emission light calculation circuit 417 from the combined current obtained via the spontaneous emission light calculation circuit 417.

  The program storage unit 419 stores a program similar to the program storage unit 216 shown in FIG. The main control circuit 418 controls the optical amplifier 451, the gain calculation circuit 413, and the input optical level calculation circuit 414 according to the program stored in the program storage unit 419. Since the control content of the main control circuit 418 is the same as that of the main control circuit 215 (see FIG. 5), the description thereof is omitted here.

  As described above, according to the sixth embodiment of the present invention, the input light level calculation circuit 414 calculates the input light in consideration of the spontaneous emission light level calculated by the spontaneous emission light calculation circuit 417. Is possible. Therefore, according to the sixth embodiment, it is possible to calculate the level of input light more accurately than in the fourth and fifth embodiments that do not have the spontaneous emission light calculation circuit 417.

  In the present invention, backward excitation is illustrated as an excitation method for EDFs 205, 305, and 405, but the same effect can be obtained by forward excitation or bidirectional excitation method. In the present invention, the case where the optical amplifiers (EDFA) 251, 351, and 451 are configured in one stage is shown, but the same effect can be obtained even in a multistage configuration.

1 is a configuration diagram of a first embodiment of an optical amplifying device according to the present invention. FIG. It is a flowchart which shows operation | movement of 1st Embodiment of the optical amplifier which concerns on this invention. It is a block diagram of 2nd Embodiment of the optical amplifier which concerns on this invention. It is a flowchart which shows operation | movement of 2nd Embodiment of the optical amplifier which concerns on this invention. It is a block diagram of 4th Embodiment of the optical amplifier which concerns on this invention. It is a block diagram of 5th Embodiment of the optical amplifier which concerns on this invention. It is a block diagram of 6th Embodiment of the optical amplifier which concerns on this invention. It is a block diagram of an example of a related optical amplifier.

Explanation of symbols

1-4 Optical amplifier
11 Combined part
12 Optical amplifier 251, 351, 451 Optical amplifier
13 First branch
14 Second branch
15 Gain calculation circuit
16 filters
17 Input light level calculation circuit
21 Optical demultiplexer
25 Input light level control circuit
26 Light source for probe 252, 352, 452 Optical demultiplexer 201, 301, 401 Combined coupler 202, 302, 402 Light source for probe
203 Input light level control circuit 205, 305, 405 Erbium-doped optical fiber (EDF)
206, 306, 406 WDM coupler 207, 307, 407 Excitation light source 208, 209, 308 Branch coupler 309, 315, 408 Branch coupler
409, 415 Branch coupler 210, 310, 410 Probe light separation filter 211, 212, 311 Photo diode 312, 316, 411 Photo diode
412, 416 Photodiode 213, 313, 413 Gain calculation circuit 214, 314, 414 Input light level calculation circuit 215, 317, 418 Main control circuit 216, 318, 419 Program storage unit 217, 319, 420 Input terminal 218, 320, 421 Output terminal
303 Input light level conversion circuit
304, 404 Input light level constant control circuit
403 Input light level conversion circuit
417 Spontaneous emission calculation circuit

Claims (18)

A probe light source for outputting probe light;
An input light level control circuit for driving the probe light source;
A multiplexing unit that combines the input light and the probe light;
An optical amplifier that amplifies the combined light combined by the combining unit;
An optical demultiplexer for branching the combined light amplified by the optical amplifier and separating the probe light from a part of the branched combined light;
The gain of the optical amplifier is calculated based on the level of the probe light before being multiplexed by the multiplexing unit obtained via the input light level control circuit and the level of the probe light separated by the optical demultiplexer A gain calculating circuit to
The multiplexing unit based on the multiplexed light branched by the optical demultiplexer and the level of the separated probe light obtained via the gain calculation circuit and the gain of the optical amplifier calculated by the gain calculation circuit An input light level calculation circuit that calculates the level of the input light before being combined at
An optical amplifying device comprising:   The input light level calculation circuit subtracts the probe light level separated by the optical demultiplexer from the level of the multiplexed light branched by the optical demultiplexer, and the subtraction result is obtained by the gain calculation circuit. 2. The optical amplifying apparatus according to claim 1, wherein the level of the input light before being multiplexed by the multiplexing unit is calculated by performing reverse calculation based on the gain of the optical amplifier. The optical demultiplexer includes a first branching unit that branches the multiplexed light amplified by the optical amplifier;
A second branching part for further branching one of the branched lights branched by the first branching part;
A filter that separates the probe light from one of the branched lights branched by the second branch part;
A first photodiode that electrically converts probe light separated by the filter;
A second photodiode that electrically converts another one of the branched lights branched by the second branching unit;
The optical amplifying device according to claim 1, comprising:   4. The optical amplifying apparatus according to claim 1, wherein the gain calculating circuit includes a function of controlling the gain to be constant.   A third branching unit for branching a part of the probe light combined at the multiplexing unit before multiplexing, and a constant input light level for controlling the level of the light branched at the third branching unit constant 5. The optical amplifier according to claim 1, further comprising a control circuit.   A spontaneous emission light calculating circuit for calculating a level of spontaneous emission light from the level of the other branched light branched by the second branching unit, wherein the input light level calculation circuit calculates the spontaneous emission light during the calculation of the input light level; The optical amplifying apparatus according to claim 3, wherein the level is referred to. A combining step for combining the input light and the probe light;
An optical amplification step for amplifying the combined light combined in the combining step;
An optical demultiplexing step for branching the amplified combined light and separating the probe light from a part of the branched combined light;
A gain calculating step for calculating the gain of the combined light based on the level of the probe light before being combined in the combining step and the level of the probe light separated in the optical demultiplexing step;
The level of the input light before being multiplexed in the multiplexing step is calculated based on the level of the multiplexed light and the separated probe light branched in the optical demultiplexing step and the gain calculated in the gain calculation step. An input light level calculating step,
An input light level calculation method comprising:   The input light level calculation step subtracts the probe light level separated in the optical demultiplexing step from the combined light level branched in the optical demultiplexing step, and the subtraction result is obtained in the gain calculation step. The input light level calculation method according to claim 7, wherein the level of the input light before being combined in the combining step is calculated by performing reverse calculation based on the gain. The optical demultiplexing step includes a first branching step for branching the amplified combined light;
A second branching step for further branching one of the branched lights branched in the first branching step;
A filter step for separating the probe light from one of the branched lights branched in the second branching step;
A first electrical conversion step for electrically converting the probe light separated in the filter step;
A second electrical conversion step of electrically converting another one of the branched lights branched by the second branching unit;
The input light level calculation method according to claim 7 or 8, characterized by comprising:   The input light level calculation method according to claim 7, wherein the gain calculation step includes a function of controlling the gain to be constant.   A third branching step for branching a part of the probe light combined in the multiplexing step before multiplexing; and a constant input light level for controlling the level of the light branched in the third branching step constant The input light level calculation method according to claim 7, further comprising a control step.   A spontaneous emission light calculating step of calculating a level of spontaneous emission light from a level of the other branched light branched in the second branching step, wherein the input light level calculation step includes the spontaneous emission light in calculating the input light level. The input light level calculation method according to claim 9, wherein the input light level is referred to. A probe light source for outputting probe light;
An input light level control circuit for driving the probe light source;
A multiplexing unit for amplifying the input light and the probe light to be combined and input to the optical amplifier;
An optical multiplexer for branching the combined light amplified by the optical amplifier and separating the probe light from a part of the branched combined light;
The gain of the optical amplifier is calculated based on the level of the probe light before being multiplexed by the multiplexing unit obtained via the input light level control circuit and the level of the probe light separated by the optical multiplexer. A gain calculation circuit;
Based on the multiplexed light branched by the optical multiplexer and the level of the separated probe light obtained via the gain calculation circuit, and the gain of the optical amplifier calculated by the gain calculation circuit, An input light level calculation circuit for calculating the level of the input light before being combined;
An optical amplifier control device comprising:   The input light level calculation circuit subtracts the probe light level separated by the demultiplexer from the combined light level branched by the optical demultiplexer, and the subtraction result is obtained by the gain calculation circuit. 14. The optical amplifier control device according to claim 13, wherein the level of the input light before being multiplexed by the multiplexing unit is calculated by performing reverse calculation based on the gain of the optical amplifier. The optical demultiplexer includes a first branching unit that branches the multiplexed light amplified by the optical amplifier;
A second branching part for further branching one of the branched lights branched by the first branching part;
A filter that separates the probe light from one of the branched lights branched by the second branch part;
A first photodiode that electrically converts probe light separated by the filter;
A second photodiode that electrically converts another one of the branched lights branched by the second branching unit;
The optical amplifier control device according to claim 13 or 14, characterized by comprising:   16. The optical amplifier control device according to claim 13, wherein the gain calculation circuit includes a function of controlling the gain to be constant.   A third branching unit for branching a part of the probe light combined at the multiplexing unit before multiplexing, and a constant input light level for controlling the level of the light branched at the third branching unit constant 17. The optical amplifier control device according to claim 13, further comprising a control circuit.   A spontaneous emission light calculating circuit for calculating a level of spontaneous emission light from the level of the other branched light branched by the second branching unit, wherein the input light level calculation circuit calculates the spontaneous emission light during the calculation of the input light level; The optical amplifier control device according to claim 15, wherein the level is referred to.

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