JP6485901B2 - Control method of optical device - Google Patents

Description

  The present invention relates to an optical device control method.

  An optical amplification device including an optical amplifier such as a semiconductor optical amplifier (SOA) may be provided between devices that perform optical transmission communication. In this optical amplifying device, the output light from the optical transmitter is detected by the detecting means, and the optical amplifier is controlled (APC: Automatic Power Control) to obtain a desired optical output. Here, since the intensity of the light input to the optical amplifier is not constant, the light is once attenuated in order to obtain an optical output amplified to a desired gain range.

  For example, Patent Document 1 discloses a front-stage optical amplifier and a rear-stage optical amplifier that amplify an optical signal, a variable optical attenuator positioned between the front-stage optical amplifier and the rear-stage optical amplifier, and the intensity of light output from the front-stage optical amplifier. A first photodetector that detects the intensity of light, a second photodetector that detects the intensity of light output from the variable optical attenuator, and a third photodetector that detects the intensity of light output from the subsequent optical amplifier. An optical amplifying device having the following is disclosed.

JP-A-8-248455

  In the optical amplifying device as described above, the optical amplification amount of the front-stage optical amplifier and the rear-stage optical amplifier and the optical attenuation amount of the variable optical attenuator are respectively adjusted according to the detection results of the first to third optical detectors. ing. In this case, since a plurality of light detection results are used, a complicated calculation is required to obtain a desired light output. Moreover, since the first to third photodetectors are included in the optical amplifying device, the size of the device is increased.

  An object of the present invention is to provide a method of controlling an optical device that can easily obtain a desired light output and can contribute to miniaturization.

  An optical device control method according to an aspect of the present invention includes an optical attenuator to which signal light is input, an optical amplifier that amplifies signal light output from the optical attenuator, and signal light output from the optical amplifier. A first step of setting the attenuation factor of the optical attenuator to a first predetermined value; and a second step of setting the amplification factor of the optical amplifier to a second predetermined value. And a third step of lowering the attenuation rate of the optical attenuator so that the intensity of light approaches the target value based on the detection result of the intensity of light input to the detection means via the optical attenuator and the optical amplifier. In the third step, when the optical attenuator does not attenuate the light intensity and the detected light intensity does not reach the target value, the amplification factor of the optical amplifier is set to a value larger than the second predetermined value. And a fourth step of setting.

  ADVANTAGE OF THE INVENTION According to this invention, the control method of the optical apparatus which can obtain a desired optical output easily and can contribute to size reduction can be provided.

FIG. 1 is a schematic diagram illustrating a usage example of an optical amplifying device included in the optical device according to the present embodiment. FIG. 2 is a block diagram of the optical device according to the present embodiment. FIG. 3 is a plan sectional view showing a detailed configuration of the optical amplifying device. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a flowchart illustrating a method for controlling the optical device according to the first embodiment. FIG. 6 is a graph showing the relationship between the current value flowing through the optical amplifier and the amplification factor of the light amplified by the optical amplifier. FIG. 7 is a block diagram of an optical device according to a comparative example. FIG. 8 is a flowchart illustrating a method of controlling the optical device according to the second embodiment. FIG. 9 is a graph showing a change in intensity of light transmitted through the optical amplifying device.

[Description of Embodiment of Present Invention]
First, the contents of the embodiments of the present invention will be listed and described. An embodiment of the present invention includes an optical attenuator to which signal light is input, an optical amplifier that amplifies the signal light output from the optical attenuator, and detection means that detects the intensity of the signal light output from the optical amplifier. A first step of setting the attenuation factor of the optical attenuator to a first predetermined value, a second step of setting the amplification factor of the optical amplifier to a second predetermined value, and an optical attenuator And a third step of lowering the attenuation rate of the optical attenuator so that the intensity of light approaches the target value based on the detection result of the intensity of light input to the detection means via the optical amplifier, and When the optical attenuator does not attenuate the light intensity and the detected light intensity does not reach the target value, the amplification factor of the optical amplifier is set to a value larger than the second predetermined value. And a method for controlling the optical device.

  According to the control method of the optical device, after setting the attenuation rate of the optical attenuator to the first predetermined value, based on the detection result of the intensity of light input to the detection means via the optical attenuator and the optical amplifier, The attenuation factor of the optical attenuator can be lowered so that the intensity of the light approaches the target value. This makes it easy to adjust the attenuation factor of the optical attenuator so that the intensity of the light output from the optical amplifier approaches the target value even when the intensity of the output light from the optical attenuator is not detected. Can do. That is, even if the optical device does not include a plurality of detection means, the attenuation factor of the optical attenuator can be easily adjusted. In addition, in the third step, even if the optical attenuator does not attenuate the light intensity and the detected light intensity does not reach the target value, the amplification factor of the optical amplifier is set to the second step. By setting the value larger than the predetermined value, the intensity of the light can be brought close to the target value. Therefore, it is possible to suppress an increase in size of the optical device and easily obtain a desired light output by the optical amplifier.

  Further, the first predetermined value set in the first step may be a value that makes the detection means unable to detect the light intensity. In this case, the detection unit detects light in the first step, and the control unit is prevented from operating.

[Details of the embodiment of the present invention]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are used for the same elements or elements having the same functions, and redundant description is omitted.

(First embodiment)
FIG. 1 is a schematic diagram illustrating a usage example of an optical amplifying device included in the optical device according to the first embodiment. As shown in FIG. 1, the optical amplifying apparatus 1 is provided between an optical transmitter 2 and an optical receiver 3. The optical amplifying apparatus 1 includes an optical fiber 4 to which a connector 4a is attached and an optical fiber 5 to which a connector 5a is attached. The connector 4a is provided so as to be connected to the connector 6a of the optical fiber 6 connected to the optical transmitter 2, for example. The connector 5a is provided so as to be connected to the connector 7a of the optical fiber 7 connected to the optical receiver 3, for example. Therefore, for example, light propagating through the optical fibers 4 and 6 is input to the optical amplifying apparatus 1. The optical amplifying apparatus 1 outputs light propagating through the optical fibers 5 and 7 to the optical receiver 3, for example.

  FIG. 2 is a block diagram of the optical device according to the first embodiment. As shown in FIG. 2, the optical device 30 includes an optical amplification device 1 and a control unit 21 that controls the optical amplification device 1. The optical amplifying apparatus 1 includes an optical attenuator (VOA) 12, an optical amplifier (SOA) 13, a splitter 14, and a light detection unit (detection means) 15 that detects the intensity of light. Have. For example, the light (input light) L 1 is input to the optical attenuator 12 and the light L 2 is output, and the light (output light) L 3 is output from the optical amplifier 13. A part of the light L3 passes through the splitter 14 and is emitted to the outside. The other part of the light L 3 is reflected by the splitter 14 and input to the light detection unit 15. The lights L1 to L3 are, for example, signal light or adjustment light. The light L2 corresponds to the light L1 transmitted through the optical attenuator 12, and the light L3 corresponds to the light L2 transmitted through the optical amplifier 13.

  The optical attenuator 12 absorbs the input light and attenuates the intensity of the light. The optical attenuator 12 has a semiconductor laminated structure, for example, a structure in which a cladding layer, an optical attenuation layer, a cladding layer, a contact layer, and an electrode are laminated in order. The light attenuation layer may have, for example, a quantum well structure (MQW: Multi Quantum Well).

  The optical amplifier 13 amplifies the input light. The optical amplifier 13 has a semiconductor laminated structure like the optical attenuator 12, and has a structure in which, for example, a clad layer, an optical amplification layer, a clad layer, a contact layer, and an electrode are laminated in order. The optical amplification layer has, for example, a quantum well structure.

  The control unit 21 sets the attenuation rate of the optical attenuator 12 to a predetermined value (first predetermined value). This predetermined value is, for example, the maximum rate that can be attenuated by the optical attenuator 12. The control unit 21 controls the attenuation rate of the optical attenuator 12 to change from the predetermined value based on the detection result of the intensity of the light L3 by the light detection unit 15. For example, the control unit 21 performs control so that the attenuation rate of the optical attenuator 12 is gradually decreased (the intensity of the light L2 output from the optical attenuator 12 is increased) based on the detection result of the light detection unit 15. The change in the attenuation factor of the optical attenuator 12 by the control unit 21 is control by feedback, and is performed after setting the attenuation factor of the optical attenuator 12 and the amplification factor of the optical amplifier 13 (the optical amplifier 13 will be described later). ).

  The control unit 21 sets the amplification factor of the optical amplifier 13 to a predetermined value (second predetermined value). This predetermined value is in a range (setting range) in which, for example, the intensity of light input to the optical amplifier 13 can be stably amplified. The maximum value of the predetermined value is, for example, 15 dB. Further, the control unit 21 controls the amplification factor of the optical amplifier 13 to change from the predetermined value based on the detection result of the intensity of the light L3 by the light detection unit 15. For example, the control unit 21 can set the amplification factor of the optical amplifier 13 to a value larger than a predetermined value. As a specific example, when it is determined that the setting range of the predetermined value of the optical amplifier 13 is 5 dB to 15 dB and the amplification factor of the optical amplifier 13 is 15 dB, the intensity (gain) of the light L3 is insufficient. 21 may set the amplification factor of the optical amplifier 13 in the range of 16 dB to 20 dB. The change of the amplification factor of the optical amplifier 13 by the control unit 21 is control by feedback, and is performed after the control of the optical attenuator 12 is completed.

  By controlling the optical attenuator 12 and the optical amplifier 13 of the control unit 21 as described above, the intensity of the light L3 output from the optical amplifying apparatus 1 is brought close to the target value. This target value is the intensity of light output from the optical amplifying apparatus 1, which is obtained by the optical receiver 3 in FIG. 1.

  Next, a detailed configuration of the optical amplifying apparatus 1 will be described with reference to FIGS. 3 and 4. FIG. 3 is a plan sectional view showing a detailed configuration of the optical amplifying apparatus 1. 4 is a cross-sectional view taken along line IV-IV in FIG. As shown in FIGS. 3 and 4, the optical amplifying apparatus 1 includes an optical amplifier 13 and a package 40 that houses the optical amplifier 13, a first optical connection unit 41, a second optical connection unit 42, and lenses 43 and 44. Prepare.

  The package 40 is a hollow member having a substantially rectangular parallelepiped appearance. The package 40 has side walls 40a and 40b facing each other, and side walls 40c and 40d facing each other and extending in a direction perpendicular to the side walls 40a and 40b. The package 40 includes a bottom plate 40i and a top plate 40j. The package 40 is made of, for example, an Fe—Ni—Co alloy except for the bottom plate 40i. The bottom plate 40i is made of, for example, a CuW alloy having excellent thermal conductivity. The side wall 40a includes a joint surface 40e on the outer surface. A first optical connection portion 41 to be described later is fixed to the joint surface 40e. An opening 40g is formed in the side wall 40a. A lens 43 is fixed to the opening 40g, and an optical axis D1 extending from one end of the optical attenuator 12 passes through the lens 43. Side wall 40b includes joint surface 40f on the outer surface. Further, an opening 40h is formed in the side wall 40b. A lens 44 is fixed to the opening 40 h, and an optical axis D <b> 2 extending from one end of the optical amplifier 13 passes through the lens 44.

  In addition to the optical attenuator 12 and the optical amplifier 13, the package 40 includes a subcarrier 45, a first collimating lens 46, a second collimating lens 47, a thermistor 48, carriers 49a and 49b, and a temperature control unit (TEC: Thermo Electric Cooler). ) Contains T. The optical attenuator 12 is mounted on the carrier 49a. On the carrier 49b on the temperature control unit T, a subcarrier 45 on which the optical amplifier 13 is mounted, a first collimating lens 46, a second collimating lens 47, and a thermistor 48 are mounted.

  The optical attenuator 12 is sandwiched between the lens 43 and the first collimating lens 46. The first end surface 12 a of the optical attenuator 12 is optically coupled to the lens 43. The second end face 12 b of the optical attenuator 12 is optically coupled to the first collimating lens 46.

  The optical amplifier 13 is sandwiched between the first collimating lens 46 and the second collimating lens 47. The first end face 13 a of the optical amplifier 13 is optically coupled to the first collimating lens 46. The second end face 13 b of the optical amplifier 13 is optically coupled to the second collimating lens 47. In order to reduce the return light from the first end surface 13a and the second end surface 13b of the optical amplifier 13, the first end surface 13a and the second end surface 13b are inclined with respect to the surfaces perpendicular to the optical axis D1 and the optical axis D2. Facing each other.

  The subcarrier 45 is a member on which the optical amplifier 13 is mounted, and is made of, for example, AlN. The temperature control unit T is, for example, a Peltier element. The thermistor 48 is installed in the vicinity of the optical amplifier 13 in order to detect the temperature of the optical amplifier 13.

  An opening is formed in the side wall 40d, and a feedthrough 50 is provided in the opening. For example, metal wires 52 a to 52 h are provided in the feedthrough 50, and the metal wires 52 a to 52 h are electrically connected to the temperature control unit T, the optical attenuator 12, the optical amplifier 13, and the thermistor 48, respectively. The feedthrough 50 is further provided with external terminals 53a to 53h connected to the metal wirings 52a to 52h, respectively. The external terminals 53a to 53h are used as a drive terminal for the optical amplifier 13, a drive terminal for the optical attenuator 12, a terminal for the temperature control unit T, and a terminal for the thermistor 48, for example. The optical attenuator 12, the optical amplifier 13, and the thermistor 48 are connected to the outside of the optical amplifying apparatus 1 (for example, the control unit 21 shown in FIG. 2) via the metal wirings 52a to 52h and the external terminals 53a to 53h. Send and receive electrical signals. The feedthrough 50 is made of, for example, ceramic, and the metal wirings 52a to 52h and the external terminals 53a to 53h are made of, for example, Au.

  The first optical connecting portion 41 is made of, for example, stainless steel, is fixed to the joint surface 40e of the package 40 by welding or the like, and passes the optical axis D1 extending from the first end surface 12a of the optical attenuator 12. The first optical connection unit 41 is, for example, an optical receptacle. A stub 61 is accommodated inside the first optical connecting portion 41, and an optical cable 62 that accommodates an optical fiber is attached. The stub 61 is optically coupled to the lens 43. The stub 61 is an optical coupling component for an optical receptacle, and is made of, for example, ceramic. The optical cable 62 is optically coupled to the stub 61.

  The second optical connection portion 42 is made of, for example, stainless steel, is fixed to the joint surface 40f of the package 40 by welding or the like, and allows the optical axis D2 extending from the second end surface 13b of the optical amplifier 13 to pass therethrough. A stub 63 is accommodated inside the second optical connection portion 42, and an optical cable 64 that accommodates an optical fiber is attached.

  Next, an example of an optical device control method according to the first embodiment will be described with reference to FIG. FIG. 5 is a flowchart illustrating a method for controlling the optical device according to the first embodiment.

  As shown in FIGS. 2 and 5, first, as a first step, the control unit 21 sets the attenuation factor of the optical attenuator 12 to a predetermined value (first predetermined value) (step S1). For example, the attenuation rate of the optical attenuator 12 is set by applying a predetermined voltage to the optical attenuator 12. The attenuation rate of the optical attenuator 12 in the first embodiment is the maximum rate that can be attenuated by the optical attenuator 12. The voltage applied to the optical attenuator 12 is, for example, a reverse bias (less than 0V). In step S1, the amplification factor of the optical amplifier 13 is preferably zero. That is, it is preferable that the predetermined value set in step S1 is a value that makes the light detection unit 15 unable to detect the light intensity. In this case, the current flowing through the optical amplifier 13 is 0 mA, which is preferable because spontaneous emission amplified light (ASE) from the optical amplifier 13 is suppressed.

  Next, as a second step, light is input to the optical attenuator 12 (step S2). This light is, for example, adjustment light used when the optical amplifying apparatus 1 is inspected before shipment or is driven. Since the optical attenuator 12 is set so as to attenuate the light input in step S <b> 1, all or most of the light is absorbed by the optical attenuator 12.

  Next, as a third step, after the second step, the amplification factor of the optical amplifier 13 is set to a predetermined value (second predetermined value) (step S3). For example, the gain of the optical amplifier 13 is set by setting the control unit 21 so that a current in a predetermined range flows through the optical amplifier 13. FIG. 6 is a graph showing an example of the relationship between the current value flowing through the optical amplifier 13 and the amplification factor of the optical amplifier 13. In FIG. 6, the vertical axis represents the amplification factor of the optical amplifier 13, and the horizontal axis represents the current value IS flowing through the optical amplifier 13. Based on the graph shown in FIG. 6, for example, by setting the current flowing through the optical amplifier 13 to 30 mA to 70 mA, the amplification factor of the optical amplifier 13 can be set in the range of 5 dB to 15 dB.

  Next, as a fourth step, it is confirmed whether or not the intensity of the light output from the optical amplifier 13 has exceeded a target value (step S4). When the intensity of the light output from the optical amplifier 13 does not exceed the target value (step S4: NO), as the fifth step, the intensity of the light output from the optical amplifier 13 is detected by the light detection unit 15, and this Based on the detection result, the attenuation factor of the optical attenuator 12 is lowered (step S5). For example, the intensity of the light output from the optical amplifier 13 is brought closer to the target value by gradually decreasing the attenuation rate of the optical attenuator 12 based on the detection result of the light intensity by the light detector 15. Step S4 is performed again after step S5.

  When the intensity of the light output from the optical amplifier 13 exceeds the target value (step S4: YES), the light detection unit 15 detects the intensity of the light output from the optical amplifier 13 as a sixth step, The amplification factor of the amplifier 13 is lowered (step S6). In step S6, for example, automatic output control (APC) by the control unit 21 is performed. If step S6 does not need to be performed, step S6 may be omitted.

  The effects obtained by the method for controlling the optical device 30 according to the first embodiment described above will be described. FIG. 7 is a block diagram of an optical device according to a comparative example. The optical amplifying device 100 included in the optical device 130 of the comparative example shown in FIG. 7 includes an optical attenuator 12 and an optical amplifier 13. In addition, the optical amplifying device 100 includes splitters 101 to 103 and photodiodes 104 to 106. The intensity of the light L1 input to the optical amplifying device 100 is detected by the splitter 101 and the photodiode 104. Further, the intensity of the light L 2 attenuated by the optical attenuator 12 is detected by the splitter 102 and the photodiode 105. The intensity of the light L3 output from the optical amplifier 13 is detected by the splitter 103 and the photodiode 106. The control unit 21 controls the optical attenuator 12 and the optical amplifier 13 based on the detection results of the photodiodes 104 to 106. In such an optical amplifying apparatus 100, a desired light output can be easily obtained by the control of the control unit 21, but there is a problem that the optical amplifying apparatus 100 is enlarged by the splitters 101 to 103 and the photodiodes 104 to 106. Moreover, since the control part 21 uses the detection result of the photodiodes 104-106, in order to control the optical attenuator 12 and the optical amplifier 13, a complicated calculation is needed.

  In contrast, in the optical device 30 having the optical amplifying device 1 and the control unit 21 according to the first embodiment, for example, the output light from the optical attenuator 12 using the splitter 101 and the photodiode 104 of the optical amplifying device 100 is used. Even when the intensity or the like is not detected, the attenuation factor of the optical attenuator 12 can be easily adjusted so that the intensity of the light output from the optical amplifier 13 approaches the target value. That is, the attenuation factor of the optical attenuator 12 can be easily adjusted even if the optical amplifying apparatus 1 does not include a plurality of light detection units 15. Therefore, it is possible to suppress the enlargement of the optical device 30 and to easily obtain a desired light output by the optical amplifier 13.

  Further, the first predetermined value set in step S1 may be a state where the light detection unit 15 cannot detect the light intensity. In this case, it is suppressed that the light detection part 15 detects light in step S1, and the control part 21 operate | moves.

  Further, step S2 for inputting light to the optical attenuator 12 after step S1 and before step S3 may be further included. In this case, for example, light that is not attenuated by the optical attenuator 12 during adjustment of the optical amplifying device 1 is not input to the optical amplifier 13. Thereby, it is possible to suppress light having excessive intensity from being output from the optical amplifier 13 and input to the optical receiver 3 or the like shown in FIG.

  Further, the predetermined value set in step S <b> 1 may be a maximum rate that can be attenuated by the optical attenuator 12. In this case, light leakage from the optical attenuator 12 can be suppressed in step S1.

  Further, the control method of the optical device 30 according to the first embodiment includes the step S1 for setting the attenuation factor of the optical attenuator 12 to a first predetermined value and the amplification of the optical amplifier 13 as in the second embodiment described later. Based on the detection result of the intensity of light input to the light detection unit 15 through the optical attenuator 12 and the optical amplifier 13 in step S3 for setting the rate to the second predetermined value, the light intensity is brought close to the target value. When the optical attenuator 12 does not attenuate the light intensity in step S5 and the optical attenuator in step S5, the optical amplifier detects that the detected light intensity does not reach the target value. And a step of setting the amplification factor of 13 to a value larger than the second predetermined value (fourth step). In this case, in addition to the above-described effects, even when the optical attenuator 12 does not attenuate the light intensity and the detected light intensity does not reach the target value, the amplification factor of the optical amplifier 13 Is set to a value larger than the second predetermined value, the intensity of the light can be brought close to the target value.

(Second Embodiment)
Below, the control method of the optical apparatus which concerns on 2nd Embodiment is demonstrated. In the description of the second embodiment, descriptions overlapping with the first embodiment are omitted, and only the parts different from the first embodiment are described. In other words, the description of the first embodiment may be used as appropriate for the second embodiment within the technically possible range.

  FIG. 8 is a flowchart illustrating a method of controlling the optical device according to the second embodiment. As shown in FIG. 8, in the second embodiment, when the intensity of the light output from the optical amplifier 13 does not exceed the target value (step S4: NO), the optical attenuator 12 is light (adjustment light). ) Is attenuated (step S11). When the optical attenuator 12 attenuates light (step S11: YES), step S4 is performed again after performing step S5.

  In the case where the optical attenuator 12 has not attenuated light (that is, the attenuation factor of the optical attenuator 12 is 0) (step S11: NO), the intensity of the light detected by the light detection unit 15 is the target. When the value does not exceed (that is, step S4: NO), the amplification factor of the optical amplifier 13 is set to a value larger than a predetermined value (second predetermined value) (step S12). This step S <b> 12 is performed while detecting the intensity of the light output from the optical amplifier 13 by the light detection unit 15. If it is necessary to perform step S6 after step S12, step S6 is performed, and the operation is terminated.

  Even if it is the control method of the optical apparatus 30 which concerns on 2nd Embodiment mentioned above, there exists an effect similar to 1st Embodiment. In addition, in step S12, even if the optical attenuator 12 does not attenuate the light intensity and the detected light intensity does not reach the target value, the amplification factor of the optical amplifier 13 is set to the second value. By setting the value larger than the predetermined value, the intensity of the light can be brought close to the target value.

  The intensity of the light L3 may be detected by a photodiode (not shown) in the optical receiver 3 connected to the optical amplifying device 1 shown in FIG. In this case, even if no photodiode is provided in the optical amplifying device 1, the optical amplifier 13 can be suitably controlled by feedback according to the intensity of the light L3.

  Here, in the case where the intensity of the light for adjustment is different, an example of the result of performing Steps S1 to S6 and Steps S11 and S12 is shown in Table 1 below. Table 1 below shows the intensity Pin of the light (input light) input to the optical attenuator 12, the attenuation factor VOA: ATT of the optical attenuator 12, the amplification factor SOA: Amp of the optical amplifier 13, and the optical amplifier 13. The intensity Pout of the output light (output light) is shown. The intensity Pout of the output light is a target value and is a constant value. In order to obtain the results shown in Table 1 below, the maximum value of the attenuation factor of the optical attenuator 12 was set to -30 dB, and the intensity Pout of the output light as the target value was set to -5 dBm. In addition, the amplification factor of the optical amplifier 13 in step S3 was 15 dB, and the maximum amplification factor of the optical amplifier 13 in step S12 was 20 dB.

  FIG. 9 is a graph showing a change in intensity of light transmitted through the optical amplifying apparatus 1. In FIG. 9, the vertical axis indicates the intensity of light, and the horizontal axis indicates the position of light. In the horizontal axis of FIG. 9, α is an arbitrary position of light input to the optical attenuator 12, VOAin is a position where light is input to the optical attenuator 12, and SOAin is an optical amplifier 13 in which attenuated light is attenuated. , And β is an arbitrary position of the light output from the optical amplifier 13. The light intensity at α is Pin, and the light intensity at β is Pout. Each graph ah shown in FIG. 9 corresponds to ah in Table 1.

  As shown in FIG. 9 and Table 1 above, for example, the light intensity Pin shown in the graph h is 10 dBm, and when it exceeds VOAin, it is attenuated to −20 dBm. As shown in FIGS. 5 and 7, since the amplification factor of the optical amplifier 13 is 15 dB in step S3, the light intensity Pout becomes −5 dBm in step S4. As a result, as shown in FIG. 9 and Table 1 above, light having an intensity of −5 dBm, which is the target value, was output from the optical amplifying apparatus 1.

  For example, the light intensity Pin shown in the graph d is −10 dBm. When the optical attenuator 12 is attenuated to the maximum extent, the attenuation factor of the optical attenuator 12 is −30 dB. Therefore, if it exceeds VOAin, it will attenuate to -40dBm. As shown in FIGS. 5 and 7, since the amplification factor of the optical amplifier 13 is 15 dB in step S3, the light intensity Pout becomes −25 dBm in step S4, and the intensity of light output from the optical amplifier 13 is the target. It was judged that the value was not exceeded. In this case, by setting the attenuation factor of the optical attenuator 12 to −10 dB through step S5, as shown in FIG. 9 and Table 1 above, light having an intensity of −5 dBm, which is the target value, is obtained in the optical amplifying apparatus 1. Was output from.

  For example, the light intensity Pin shown in the graph a is −25 dBm. When the optical attenuator 12 is attenuated to the maximum extent, the attenuation factor of the optical attenuator 12 is −30 dB. Therefore, when it exceeds VOAin, it attenuates to -55 dBm. As shown in FIGS. 5 and 7, since the amplification factor of the optical amplifier 13 is 15 dB in step S3, the light intensity Pout becomes −40 dBm in step S4, and the intensity of light output from the optical amplifier 13 is the target. It was judged that the value was not exceeded. Even if the attenuation factor of the optical attenuator 12 is set to 0 dB through step S5 (that is, the optical attenuator 12 does not attenuate light), the intensity of the light output from the optical amplifier 13 in step S4 exceeds the target value. It was judged that it was not. In this case, since the amplification factor of the optical amplifier 13 is set to 20 dB in step S12, light having an intensity of −5 dBm, which is a target value, is transmitted from the optical amplifying apparatus 1 as shown in FIG. Was output.

  The optical device 30 according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, in the above embodiment, step S1 and step S2 may be performed simultaneously. In the above embodiment, the attenuation rate of the optical attenuator 12 set in step S1 is not necessarily the maximum rate that can be attenuated by the optical attenuator 12. For example, the attenuation rate may be smaller than the maximum rate. Further, when it is not necessary to perform at least one of steps S1 to S6 and steps S11 and S12, the step may be omitted.

  In the above embodiment, the temperature of the optical attenuator 12 may also be controlled. In this case, the carrier 49a on which the optical attenuator 12 is mounted may be mounted on the temperature control unit. Further, a thermistor or the like may be mounted on the carrier 49a.

  DESCRIPTION OF SYMBOLS 1 ... Optical amplifier, 12 ... Optical attenuator, 13 ... Optical amplifier, 14 ... Splitter, 15 ... Optical detection part, 21 ... Control part, 30 ... Optical apparatus, L1, L2, L3 ... Light.

Claims (1)

An optical attenuator to which signal light is input; an optical amplifier that amplifies the signal light output from the optical attenuator; and an intensity of the signal light output from the optical amplifier; In an optical device comprising a single light detector provided only in
A first step of setting the attenuation factor of the optical attenuator to a first predetermined value;
A second step of setting the amplification factor of the optical amplifier to a second predetermined value;
Based on the detection result of the light intensity input to the one light detection unit via the optical attenuator and the optical amplifier, the attenuation rate of the optical attenuator is lowered so that the light intensity approaches a target value. A third step;
In the third step, when the light attenuator does not attenuate the light intensity, and the light intensity detected by the one light detection unit does not reach the target value, the optical amplifier And a fourth step of setting the amplification factor to a value larger than the second predetermined value.

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