Abstract:
An optical amplification device includes: an optical module that outputs an amplified light; and a controller that makes the optical module emit a light when an emission command is input into the controller, wherein the controller cancels an inputting of the emission command until a predetermined time passes, when a protection for forbidding a light emission of the optical module is canceled.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2013-104558, filed on May 16, 2013, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    A certain aspect of embodiments described herein relates to an optical amplification device and a method of controlling an optical module. 
       BACKGROUND 
       [0003]    In an optical communication between stations, an optical module for optical amplification amplifies an optical signal in order to amplify a maximum output of the optical signal, For example, Japanese Patent Application Publications No. 2005-244305 (hereinafter referred to as Document 1) and No. 2010-279956 (hereinafter referred to as Document 2) disclose a countermeasure against an erroneous light emission. 
         [0004]    However, Document 1 and Document 2 lack in safety measure during canceling an light emission. 
       SUMMARY 
       [0005]    According to an aspect of the present invention, there is provided an optical amplification device including: an optical module that outputs an amplified light; and a controller that makes the optical module emit a light when an emission command is input into the controller, wherein the controller cancels an inputting of the emission command until a predetermined time passes, when a protection for forbidding a light emission of the optical module is canceled. 
         [0006]    According to another aspect of the present invention, there is provided a method of controlling an optical module comprising canceling inputting of an emission command until a predetermined time passes, when a protection for forbidding a light emission of an optical module that outputs an amplified light when a light emission command is input is canceled. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1A  and  FIG. 1B  illustrate a schematic view of an optical transmission system to which an optical amplification device in accordance with an embodiment is applied; 
           [0008]      FIG. 2  illustrates a structure of an optical amplification device; 
           [0009]      FIG. 3  illustrates a flowchart of an operation example of a control device; 
           [0010]      FIG. 4  illustrates a time chart of an operation of a control device; 
           [0011]      FIG. 5A  and  FIG. 5B  illustrate a register-write test; 
           [0012]      FIG. 5C  and  FIG. 5D  illustrate a case where a plurality of estimations are sequentially performed. 
           [0013]      FIG. 6  illustrates a flowchart of another example of an operation of a control device; 
           [0014]      FIG. 7  illustrates a flowchart of another example of an operation of a control device; and 
           [0015]      FIG. 8A  and  FIG. 8B  illustrate a time chart of an operation of a flowchart of  FIG. 7 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0016]      FIG. 1A  and  FIG. 1B  illustrate a schematic view of an optical transmission system to which an optical amplification device in accordance with an embodiment is applied. As illustrated in  FIG. 1A , the optical transmission device has a structure in which an optical transmission device  200  provided in each station is coupled with each other via an optical fiber. As illustrated in  FIG. 1B , the optical transmission device  200  has an optical amplification device  101 , a process device  102 , an optical amplification device  103 , and so on. The optical amplification device  101  amplifies an optical signal received from the optical transmission device  200  of another station to a power which the process device  102  can process. The process device  102  processes the optical signal amplified by the optical amplification device  101 . The optical amplification device  103  amplifies the optical signal processed by the process device  102  to a power allowing a transmission of the optical signal to a next station. 
         [0017]      FIG. 2  illustrates a structure of the optical amplification device  103 . As illustrated in  FIG. 2 , the optical amplification device  103  has an optical module  10 , a control device  20 , a CPU  30  and so on. The optical module  10  is a module for outputting an amplified light, and has an optical amplifier  11 , a light source  12  and so on. The optical amplifier  11  amplifies a signal from the process device  102  with use of a light from the light source  12 . For example, the optical amplifier  11  is a semiconductor optical amplifier. The light source  12  is, for example, a laser diode. The control device  20  is a control unit for controlling the optical module  10 . The control device  20  is, for example, structured with a FPGA (Field Programmable Gate Array) or the like. The CPU  30  is a Central Processing Unit. The CPU  30  performs a control of each device, collects an alarm or the like, and writes a command in a register of the control device  20  in accordance with an instruction from an outer component. 
         [0018]    The command written in the control device  20  by the CPU  30  includes a protection cancel command, an emission command and so on. The projection cancel command is a command for cancelling a protection prohibiting an emission of the optical module  10 . The emission command is a command for making the light source  12  emit a light. In  FIG. 2 , the protection cancel command and the emission command are written in a register of the control device  20 . 
         [0019]    The control device  20  prohibits the emission of the optical module  10  until a predetermined condition of the emission is satisfied, when the control device  20  receives a protection cancel command from the CPU  30 . In concrete, the control device  20  activates an output enable for a predetermined time after a predetermined time passes after receiving the protection cancel command from the CPU  30 . The activation of the output enable is performed by an On/Off timer unit of the control device  20 . The control device  20  inputs an emission command that is input for a time when the output enable is activated into the light source  12 , and cancels the emission command that is input for a time when the output enable command is not activated. The light source  12  inputs a light into the optical amplifier  11  when the emission command is input from the control device  20 . As mentioned above, in the embodiment, a predetermined condition relating to an emission is that the emission command is input for a time when the output enable is activated. And, the optical module  10  emits a light when the predetermined condition is satisfied. 
         [0020]      FIG. 3  illustrates a flowchart of an operation example of the control device  20 . As illustrated in  FIG. 3 , the control device  20  holds it until a protection cancel command is input by the CPU  30  (Step S 1 ). When the protection cancel command is input, the control device  20  determines whether an output enable is activated or not 
         [0021]    (Step S 2 ). When it is determined as “No” in the Step S 2 , the control device  20  cancels an emission command input by the CPU  30  (Step S 3 ). After the Step S 3 , the Step S 2  is executed again. 
         [0022]    When it is determined as “Yes” in the Step S 2 , the control device  20  determines whether an emission command is input or not (Step S 4 ). When it is determined as “No” in the Step S 4 , the Step S 2  is executed again. When it is determined as “Yes” in the Step S 4 , the control device  20  determines whether the output enable is activated or not (Step S 5 ). When it is determined as “No” in the Step S 5 , the control device  20  cancels the emission command confirmed in the Step S 4  (Step S 6 ). After the Step S 6 , the Step S 1  is executed again. When it is determined as “Yes” in the Step S 5 , the control device  20  inputs an emission signal into the light source  12  (Step S 7 ). Thus, the light source  12  outputs a light to the optical amplifier  11 . Accordingly, the optical amplifier  11  amplifies the light and outputs the amplified light. 
         [0023]      FIG. 4  illustrates a time chart of an operation of the control device  20 . As illustrated in  FIG. 4 , the control device  20  activates an output enable for a predetermined time after a predetermined time passes after inputting of a protection cancel command. In  FIG. 4 , the output enable is activated in a period A. An emission command for a period when the output enable is not activated is canceled. The control device  20  inputs an emission signal into the light source  12  when an emission command is input in the period A. When the emission signal is output from the control device  20 , the optical module  10  starts outputting of an optical signal. When the optical outputting of the optical module  10  is started, the optical module  10  continues the optical outputting even if a period of the output enable is terminated. 
         [0024]    In accordance with the embodiment, the optical module  10  cancels an emission command until a predetermined time passes after the protection is canceled. Thus, the emission is forbidden. Accordingly, a safety measure is taken when the emission is allowed. For example, an erroneous emission is prevented in a continuous access such as a register-write test. When a plurality of estimations are performed continuously, an emission command is canceled even if the emission command is input in a second estimation under a condition that a protection is missed in a first estimation, because an emission enable is limited to a predetermined period after a predetermined time passes. Therefore, an erroneous emission is prevented in a continuous test or the like. 
         [0025]      FIG. 5A  and  FIG. 5B  illustrate the register-write test. As illustrated in  FIG. 5A , when an emission command is input sequentially after a protection cancel command in the register-write test, an optical module emits a light under ordinary circumstances when an emission command is input. In contrast, in the embodiment, as illustrated in  FIG. 5B , the emission command is canceled until a predetermined time passes after a protection is canceled. In this case, the optical module does not emit a light in a continuous access. Therefore, an erroneous emission is prevented. 
         [0026]      FIG. 5C  and  FIG. 5D  illustrate a case where a plurality of estimations are sequentially performed. As illustrated in  FIG. 5C , in ordinary circumstances, the optical module emits a light when an emission command is input, in a case where the emission command is input in a second estimation under a condition that a protection is missed in a first estimation. In contrast, in the embodiment, as illustrated in  FIG. 5D , an emission command is canceled even if the emission command is input in a second estimation under a condition that a protection is missed in a first estimation. That is, a cancelling of the protection is required in every estimation. Therefore, an erroneous light emission is prevented. 
         [0027]      FIG. 6  illustrates a flowchart of another example of an operation of the control device  20 . The flowchart of  FIG. 6  is executed when the optical module  10  starts to emit a light in the flowchart of  FIG. 3 . In the flowchart of  FIG. 6 , an output enable is activated again for a predetermined time when a predetermined time (for example, one minute) passes after the last output enable is inactivated. As illustrated in  FIG. 6 , the control device  20  determines whether the above-mentioned predetermined time passes or not after an emission signal is output (Step S 11 ). When it is determined as “No” in the Step S 11 , the Step S 11  is executed again. 
         [0028]    When it is determined as “Yes” in the Step S 11 , the control device  20  determines whether an output enable is activated or not (Step S 12 ). When it is determined as “No” in the Step S 12 , the control device  20  stops the light emission of the optical module  10  (Step S 13 ). After that, the execution of the flowchart is terminated. When it is determined as “Yes” in the Step S 12 , the control device  20  determines whether an emission command is input in a period when the output enable is activated (Step S 14 ). 
         [0029]    When it is determined as “No” in the Step S 14 , the Step S 13  is executed. When it is determined as “Yes” in the Step S 14 , the control device  20  continues the light emission (Step S 15 ). After that, the execution of the flowchart is terminated. After the execution of the Step S 15 , the flowchart of  FIG. 6  is executed again. In this way, an erroneous continuation of the light emission of the optical module  10  is prevented by confirming whether a predetermined condition of the light emission is satisfied at predetermined intervals when the optical output of the optical module  10  is started. 
         [0030]      FIG. 7  illustrates a flowchart of another example of an operation of the control device  20 . A flowchart of  FIG. 7  is different from the flowchart of  FIG. 3  in a point that Steps S 41  to S 43  are executed instead of the Step S 4 . In the following description, the Steps S 41  to S 43  are described. When it is determined as “Yes” in the Step S 2 , the control device  20  determines whether an emission command 1 is input or not (Step S 41 ). When it is determined as “No” in the Step S 41 , the Step S 1  is executed again. 
         [0031]    When it is determined as “Yes” in the Step S 41 , the control device  20  determines whether an emission command 2 is input or not (Step S 42 ). When it is determined as “No” in the Step S 42 , the step S 1  is executed again. When it is determined as “Yes” in the Step S 42 , the control device  20  determines whether an emission command  3  is input or not (Step S 43 ). When it is determined as “No” in the Step S 43 , the Step S 1  is executed again. When it is determined as “Yes” in the Step S 43 , the control device  20  executes the Step S 5 . In this way, in the flowchart of  FIG. 7 , the predetermined condition of the light emission is that a plurality of different emission commands are input in a predetermined order for a period when the output enable is activated. 
         [0032]      FIG. 8A  and  FIG. 8B  illustrate a time chart of the operation of the flowchart of  FIG. 7 . As illustrated in  FIG. 8A , the control device  20  activates an output enable only for a predetermined period (a period A) after a predetermined time passes after a protection cancel command is input. An emission command for a period when the output enable is not activated is canceled. When the order of the emission command input in the period A is correct, the control device  20  inputs an emission signal into the light source  12 . When the emission signal is output from the control device  20 , the optical module  10  starts to output an optical signal. 
         [0033]    On the other hand, as illustrated in  FIG. 8B , the order of the emission command input in a period when the output enable is activated is not correct, the control device  20  cancels the emission signal. Thus, an erroneous light emission is prevented. With the structure, a safety countermeasure during a canceling of the light emission can be improved. In the flowchart of  FIG. 7 , the predetermined condition is that a plurality of different emission commands are input in a predetermined order. However, the predetermined condition may be that a plurality of different emission commands are input regardless of the order. In the flowchart of  FIG. 7 , the emission of the optical module  10  may be stopped when a predetermined condition of the emission is confirmed at a predetermined interval and the predetermined condition is not satisfied, as well as the flowchart of  FIG. 6 . 
         [0034]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various change, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.