JP2001144687A - Light output control circuit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an optical output control circuit capable of controlling an optical output level to be reduced when an output terminal of an optical connector is opened, and to return the optical output level to an original state when the output terminal of the optical connector is terminated. provide. SOLUTION: Driving means 4 to 5 for controlling the amplification degree of an optical amplifier 1, optical output detecting means 2, 7 to 8 for converting a part of an optical signal output from the optical amplifier into an electric signal, optical output detecting means Feedback control means 6 for controlling the driving means so that the optical output level of the optical amplifier becomes a predetermined level based on the output signal of the optical amplifier, and reflected light detecting means 3, 9 to 11 for converting the reflected light from the light output side into an electric signal. Comparing means 12 for comparing the output signal of the light output detecting means with the output signal of the reflected light detecting means. The comparing means controls the feedback control means to increase the light output of the optical amplifier when the output level of the reflected light detecting means increases. When the output level of the optical amplifier is decreased, and subsequently the output level of the reflected light detecting means is decreased, the optical output level of the optical amplifier is controlled to a predetermined level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical output control circuit for controlling an optical output level of an optical amplifier constituting an optical communication system. The present invention relates to an optical output control circuit capable of automatically lowering the optical output level when the output terminal of the optical connector is open, and automatically returning the optical output level to the original level when the output terminal of the optical connector is terminated.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of a conventional light output control circuit. The optical output control circuit includes an optical amplifier 51 for amplifying an optical signal from an optical transmitter 50 serving as an optical signal source, and a first amplifier for branching the amplified optical signal at a constant ratio.
And a second optical splitter 53 for splitting the optical signal split by the optical splitter 52 at a fixed ratio and further splitting the reflected light from the output side at a fixed ratio. ing.

The reflected light from the output side is small when the output end is terminated, that is, when the optical connector at the output end is normally connected to the device, and when the output end is open, that is, when the output end is open. When the optical connector at the end is not connected to the device, it increases due to Fresnel reflection.

The optical amplifier 51 is connected to a laser diode 54 for excitation, and includes a laser diode driving section 55 for driving the laser diode 54 and an APC section 56 for controlling the laser diode driving section 55.

[0005] Further, an optical signal receiving element 57 for converting the sub optical signal branched by the optical splitter 52 into an electric signal, an amplifying section 58 for amplifying the converted electric signal, and reflection from the output side split by the optical splitter 53. A light reflecting / receiving element 59 for converting light into an electric signal and an amplifying section 60 for amplifying the converted electric signal are provided.

Further, an addition / subtraction unit 61 for adding / subtracting the output signals of the amplification units 58 and 60 compares the output signal of the addition / subtraction unit 61 with the reference voltage from the reference voltage source 62 to determine whether the output terminal of the optical connector is open. An optical connector disconnection detecting unit 63 for determining whether the terminal is the terminal or a set / reset circuit (hereinafter, referred to as an SR circuit) which is set when the optical output connector end is open and issues a drive stop command of the excitation laser diode to the APC unit 56. 64, a reset switch 65 for releasing the set stop command.

Next, the operation of the light output control circuit thus configured will be described. First, an optical signal output from an optical transmitter 50 as a signal source is optically amplified by an optical amplifier 51, and several percent of the main optical signal is branched by an optical splitter 52 and supplied to an optical signal receiving element 57. . The sub optical signal supplied to the optical signal light receiving element 57 is converted into an electric signal, further amplified by the amplification section 58 and input to the addition / subtraction section 61.

The optical signal passing through the optical splitter 52 is
After a few percent of the main optical signal is further split by the optical splitter 53,
Output to the outside as optical output. The branched optical signal and the reflected light from the output end of the optical connector are supplied to the light reflection light receiving element 59. The optical signal supplied to the light reflection light receiving element 59 is converted into an electric signal, further amplified by the amplifier 60 and input to the addition / subtraction unit 61.

The addition / subtraction unit 61 offsets the output signal of the amplification unit 60 with reference to the output signal of the amplification unit 58. Then, the output signal of the addition / subtraction unit 61 and the reference voltage from the reference voltage source 62 are compared by the optical connector disconnection detection unit 63 to determine whether the output end of the optical connector is open or terminated.

When the reflected light is large (when the output end of the optical connector is open), the optical connector disconnection detecting section 63 outputs the SR
The set signal is input to the circuit 64. When the SR circuit 64 is set, a drive stop command for the excitation laser diode is issued to the APC unit 56, and the optical output in the optical amplifier 51 is stopped. The stop command set in the SR circuit 64 is released by pressing the reset switch 65.

[0011]

When the open state occurs at the output end of the optical connector, the above-described conventional optical output control circuit checks and repairs the open end, and further presses the reset switch 65 manually. Therefore, there is a problem that it is necessary to cancel the stop instruction and rely on artificial work.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem. When an output end of an optical connector is opened, the optical output of an optical amplifier is automatically reduced, and The present invention is to provide an optical output control circuit that can automatically return to a predetermined optical output level when the output end of the optical output terminal is left in an open state.

[0013]

An optical output control circuit according to the present invention comprises: an optical amplifier for amplifying an optical signal; driving means for controlling the degree of amplification of the optical amplifier; and a part of the optical signal output from the optical amplifier. Optical output detecting means for converting the optical signal into an electric signal; feedback control means for controlling the driving means so that the optical output level of the optical amplifier becomes a predetermined level based on the output signal of the optical output detecting means; and reflection from the optical output side. A reflected light detecting means for converting light into an electric signal, and a comparing means for comparing an output signal of the light output detecting means and an output signal of the reflected light detecting means, wherein the comparing means increases the output level of the reflected light detecting means. The feedback control means is controlled to reduce the optical output level of the optical amplifier, and subsequently, when the output level of the reflected light detection means is reduced, the feedback control means is controlled to control the optical output level of the optical amplifier. And controls to a predetermined level.

With this configuration, when the detection level of the reflected light increases, the feedback control means is controlled to reduce the light output level, and when the detection level of the reflected light decreases, the light output level can be restored. .

Further, the feedback control means in the optical output control circuit of the present invention includes an amplifier circuit capable of changing the amplification degree, and the comparison means includes an amplification circuit of the amplification circuit of the feedback control means when the output level of the reflected light detection means increases. To reduce the optical output level of the optical amplifier, and when the output level of the reflected light detecting means subsequently decreases, the amplification degree of the amplifier circuit of the feedback control means is increased to control the optical output level of the optical amplifier to a predetermined level. Is what you do.

With this configuration, when the detection level of the reflected light increases, the amplification degree of the amplifier circuit constituting the feedback control means is reduced to lower the optical output level of the optical amplifier. By returning the amplification degree of the amplifier circuit to the original level, the optical output level can be restored.

Further, the amplifier circuit of the feedback control means in the optical output control circuit of the present invention has a configuration in which the amplification degree changes by switching the feedback resistor of the operational amplifier by the switch means.

With this configuration, when the detection level of the reflected light increases, the feedback resistor of the operational amplifier is switched by the switch means to obtain an amplification degree corresponding to the low output operation. The original amplification degree can be obtained by selecting the feedback resistor with the switch means.

Further, the amplifier circuit of the feedback control means in the optical output control circuit of the present invention has a configuration in which the amplification degree is changed by switching the resistance value of the feedback resistor formed into an electronic volume of the operational amplifier. .

With this configuration, when the detection level of the reflected light increases, the amplification degree corresponding to the low output operation is obtained by changing the resistance value of the feedback resistor formed into an electronic volume of the operational amplifier, thereby detecting the reflected light. When the level decreases, the original amplification degree can be obtained by returning the resistance value of the feedback resistor converted into an electronic volume.

Further, the amplification circuit of the feedback control means in the optical output control circuit of the present invention has a configuration in which the amplification degree changes by switching the outputs of a plurality of amplification circuits having different amplification degrees by the switch means.

According to this configuration, when the detection level of the reflected light increases, the output of the amplification circuit having an amplification degree corresponding to the low output operation is selected from the plurality of amplification circuits by the switch means, and the detection level of the reflection light is increased. When the output drops, the output of the amplifier circuit having the original amplification degree can be selected by the switch means.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of an optical output control circuit according to Embodiment 1 of the present invention. The optical output control circuit according to the present embodiment is an optical amplifier 1 that amplifies the optical input transmitted from the optical transmission device described above.
An optical splitter 2 for splitting the optical signal amplified by the optical amplifier 1 at a constant ratio, and a main optical signal split by the optical splitter 2 at a further constant ratio to output an optical output. An optical splitter 3 for splitting the reflected light from the output side at a fixed ratio.

A laser diode 4 for excitation is connected to the optical amplifier 1, and a laser diode driving unit 5 for driving the laser diode 4, and a laser diode driving unit 5
APC section 6 as feedback control means for controlling the
It has. Drive means is constituted by the laser diode 4 and the laser diode drive unit 5.

The optical output control circuit includes a photodiode 7 for converting a sub optical signal branched by the optical splitter 2 into an electric signal, an amplifying unit 8 for amplifying the electric signal, and an output from the output side split by the optical splitter 3. It includes a photodiode 9 for converting reflected light into an electric signal, and an amplifier 10 for amplifying the electric signal. The optical splitter 2, the photodiode 7, and the amplifier 8 constitute an optical output detection unit.

By the way, since the reflected light fluctuates in light, if the optical signal is converted into an electric signal in this state and further amplified, the electric signal also fluctuates, and a malfunction may occur. Therefore, in order to eliminate this, a differential amplifier, a peak hold amplifier, a bottom hold amplifier, or the like is used as the amplifier 10.

The optical output control circuit compares the output level of the detection level amplification switching section 11 and the output level of the amplification section 10 via the detection level amplification switching section 11 with which the amplification degree can be switched. An optical connector disconnection detection unit 12 is provided as comparison means. The optical splitter 3, the photodiode 9, the amplification unit 10, and the detection level amplification switching unit 11 constitute a reflected light detection unit.

The APC section 6 amplifies an output signal from the amplifier section 8 and outputs the amplified signal to the laser diode driving section 5 as a control signal. The APC section 6 has an operational amplifier 6a. A plurality of feedback resistors 6c and 6d that can be switched are connected.

The detection level amplification switching section 11 amplifies an output signal from the amplification section 10 and outputs the amplified signal to the optical connector disconnection detection section 12, and has an operational amplifier 11a. A plurality of feedback resistors 11c and 11d switched by a switch 11b are connected.

The analog switch 6b of the APC unit 6 and the analog switch 11b of the detection level amplification switching unit 11 are configured to be switched by a control signal from the optical connector disconnection detection unit 12.

Next, the operation of the light output control circuit thus configured will be described. First, the operation when the output end of the optical connector is connected to a receiving device or the like and is not in the open state will be described.

In this case, the optical input optically amplified by the optical amplifier 1 is branched by the optical splitter 2 at a fixed ratio, further split by the optical splitter 3 at a fixed ratio, and output to the outside. The sub optical signal split by the optical splitter 2 is converted into an electric signal by a photodiode 7 and amplified by an amplifier 8.
It is supplied to the unit 6.

The APC section 6 controls the laser diode 4 by controlling the laser diode driving section 5, thereby controlling the optical output of the optical amplifier 1 to be constant. Thus, from the optical amplifier 1 to the laser diode 4
The feedback control is performed by a closed loop leading to.

In this state, when the output end of the optical connector is disengaged from the receiving device or the like and becomes open, the reflected light increases and the output level of the amplifier 10 also increases. As a result, the output level of the amplification unit 10, that is, the output level of the detection level amplification switching unit 11, increases with respect to the output level of the amplification unit 8 input to the optical connector disconnection detection unit 12.

When the optical connector detachment detecting unit 12 detects an increase in the output level of the detection level amplification switching unit 11, the APC
The analog switch 6b of the section 6 is controlled to select a feedback resistor that reduces the amplification of the operational amplifier 6a from among the plurality of feedback resistors.

As a result, the output level of the APC unit 6 decreases. By controlling the laser diode driving unit 5 with the reduced output level, control is performed to reduce the amplification of the optical amplification unit 1. As a result, the optical output and amplifying unit 8
Output level decreases.

The optical connector disconnection detection unit 12 controls the analog switch 11b of the detection level amplification switching unit 11 and selects a feedback resistor for reducing the amplification of the operational amplifier 11a from among a plurality of feedback resistors. The output level of the detection level amplification switching unit 11 is reduced. By doing so, the output level of the amplification unit 8 and the output level of the detection level amplification switching unit 11 are balanced.

In this state, if the output end of the optical connector is attached to a receiving device or the like and is not in the open state,
Since the reflected light is reduced, the output level of the amplifier 10 is also reduced. As a result, the output level of the amplifier 10 is higher than the output level of the amplifier 8 input to the optical connector disconnection detector 12.
That is, the output level of the detection level amplification switching unit 11 decreases.

When the optical connector detachment detecting unit 12 detects a decrease in the output level of the detection level amplification switching unit 11, the APC
By controlling the analog switch 6b of the section 6, a feedback resistor for increasing the amplification of the operational amplifier 6a is selected from a plurality of feedback resistors.

As a result, the output level of the APC section 6 increases. By controlling the laser diode driving section 5 with the increased output level, control is performed to restore the amplification degree of the optical amplification section 1.

As a result, the output level of the amplification section 8 increases and returns to the original level. Therefore, the optical connector disconnection detection section 12 controls the analog switch 11b of the detection level amplification switching section 11 to control the plurality of feedback resistors. Then, a feedback resistor for increasing the degree of amplification of the operational amplifier 11a is selected, the output level of the detection level amplification switching unit 11 is increased, and the two output levels are balanced again.

Thus, when the reflected light increases due to the opening of the output end of the optical connector or the like, the light output level is automatically lowered, and after these light reflection factors are eliminated, the light output level is automatically returned to the original light output level again. Can be.

(Embodiment 2) FIG. 2 is a block diagram showing a configuration of an optical output control circuit according to Embodiment 2 of the present invention. The optical output control circuit according to the present embodiment is the same as that of the first embodiment except that the switching means of the feedback resistor of the APC section 6 and the detection level amplification switching section 11 is different. 1 has the same configuration.

That is, the APC section 6 is provided with an electronic volume 6e in place of the analog switch 6b and the feedback resistors 6c and 6d, and the detection level amplification switching section 11 is provided in place of the analog switch 11b and the feedback resistors 11c and 11d. The electronic volume 11e is provided.

Next, the operation of the thus configured light output control circuit will be described. The operation when the output end of the optical connector is connected to the receiving device or the like and is not in the open state is the same as in the above-described first embodiment, and will not be described.

When the output end of the optical connector is released from the receiving device or the like and becomes open, the reflected light increases, and
Output level also increases. As a result, with respect to the output level of the amplifier 8 input to the optical connector disconnection detector 12,
The output level of the amplification unit 10, that is, the output level of the detection level amplification switching unit 11, increases.

Upon detecting an increase in the output level of the detection level amplification switching unit 11, the optical connector disconnection detection unit 12
The electronic volume 6e of the unit 6 is controlled to switch to a resistance value that reduces the amplification of the operational amplifier 6a.

As a result, the output level of the APC section 6 decreases, and the laser diode driving section 5 is controlled based on the reduced output level, thereby performing control to decrease the amplification degree of the optical amplification section 1. As a result, the optical output and amplifying unit 8
Output level decreases.

Further, the optical connector detachment detecting section 12 controls the electronic volume 11e of the detection level amplification switching section 11,
It switches to a resistance value that reduces the amplification degree of the operational amplifier 11a, and lowers the output level of the detection level amplification switching unit 11. By doing so, the output level of the amplification unit 8 and the output level of the detection level amplification switching unit 11 are balanced.

In this state, if the output end of the optical connector is attached to a receiving device or the like and is no longer in the open state,
Since the reflected light is reduced, the output level of the amplifier 10 is also reduced. As a result, the output level of the amplification unit 10, that is, the output level of the detection level amplification switching unit 11 is lower than the output level of the amplification unit 8 input to the optical connector disconnection detection unit 12.

When the optical connector detachment detecting unit 12 detects a decrease in the output level of the detection level amplification switching unit 11, the APC
The electronic volume 6e of the unit 6 is controlled to switch to a resistance value that increases the amplification of the operational amplifier 6a.

As a result, the output level of the APC section 6 increases. By controlling the laser diode driving section 5 with the increased output level, control is performed to restore the amplification degree of the optical amplifier section 1 to the original level.

As a result, the output level of the amplification section 8 increases and returns to the original level. Therefore, the optical connector disconnection detection section 12 controls the electronic volume 11e of the detection level amplification switching section 11 to increase the amplification degree of the operational amplifier 11a. The output level of the detection level amplification switching unit 11 is increased by switching to the resistance value to be increased, and the two output levels are balanced again.

In this way, when the reflected light increases due to the opening of the output end of the optical connector or the like, the light output level is automatically lowered, and after these light reflection factors are eliminated, the light output level is automatically returned to the original light output level again. Can be.

(Embodiment 3) FIG. 3 is a block diagram showing a configuration of an optical output control circuit according to Embodiment 3 of the present invention. The optical output control circuit according to the present embodiment is the same as that of the above-described first embodiment except that the configuration for switching the amplification degree of the APC unit 6 and the detection level amplification switching unit 11 is different. 1 has the same configuration.

That is, the APC unit 6 includes the operational amplifier 6
a, analog switch 6b and feedback resistors 6c, 6d
, The output of the two amplifier circuits 6f and 6g having different amplification degrees is selected by the analog switch 6h. The detection level amplification switching unit 11 includes an operational amplifier 11a, an analog switch 11b, and feedback resistors 11c and 11d. Instead, the output of the two amplifier circuits 11f and 11g having different amplification degrees is selected by the analog switch 11h.

Next, the operation of the light output control circuit thus configured will be described. The operation when the output end of the optical connector is connected to the receiving device or the like and is not in the open state is the same as in the above-described first embodiment, and will not be described.

When the output end of the optical connector is released from the receiving device or the like and becomes open, the reflected light increases, so that the amplification section 10
Output level also increases. As a result, with respect to the output level of the amplifier 8 input to the optical connector disconnection detector 12,
The output level of the amplification unit 10, that is, the output level of the detection level amplification switching unit 11, increases.

When the optical connector detachment detecting unit 12 detects an increase in the output level of the detection level amplification switching unit 11, the APC
The analog switch 6h of the section 6 is controlled to switch to the amplifier circuit 6g having a low amplification degree. The amplification degree of the amplifier circuits 6f and 6g is higher in the amplifier circuit 6f.

As a result, the output level of the APC section 6 decreases, and the laser diode driving section 5 is controlled based on the reduced output level, thereby performing control to reduce the amplification degree of the optical amplification section 1. As a result, the optical output and amplifying unit 8
Output level decreases.

The optical connector disconnection detecting section 12 controls the analog switch 11h of the detection level amplification switching section 11 to switch to the amplifier circuit 11g having a low amplification degree. The amplification degree of the amplifier circuits 11f and 11g is higher in the amplifier circuit 11f. By doing so, the output level of the amplification unit 8 and the output level of the detection level amplification switching unit 11 are balanced.

In this state, if the output end of the optical connector is attached to a receiving device or the like and is not in the open state,
Since the reflected light is reduced, the output level of the amplifier 10 is also reduced. As a result, the output level of the amplification unit 10, that is, the output level of the detection level amplification switching unit 11 is lower than the output level of the amplification unit 8 input to the optical connector disconnection detection unit 12.

When the optical connector disconnection detecting section 12 detects a decrease in the output level of the detection level amplification switching section 11, it detects the APC.
The analog switch 6h of the section 6 is controlled to switch to the amplifier circuit 6f having a high amplification degree.

As a result, the output level of the APC section 6 increases, and by controlling the laser diode driving section 5 with the increased output level, control is performed to restore the amplification degree of the optical amplifier section 1 to the original level.

As a result, the output level of the amplification unit 8 increases and returns to the original level. The optical connector disconnection detection unit 12 controls the analog switch 11h of the detection level amplification switching unit 11 to control the amplification circuit 11f having a high amplification degree. To increase the output level of the detection level amplification switching unit 11 so that the two output levels are balanced again.

In this way, when the reflected light increases due to the opening of the output end of the optical connector or the like, the light output level is automatically lowered, and after these light reflection factors are eliminated, the original light output level is automatically restored again. Can be.

[0068]

As described above, according to the present invention, when the level of the reflected light from the output terminal increases, such as when the output terminal of the optical connector is opened, the optical output level of the optical amplifier is reduced. By automatically lowering, for example, it is possible to prevent a high-level laser beam from directly looking at the worker when performing work such as detaching and attaching an optical connector, and the open state of the output terminal is eliminated when the connection of the optical connector is completed. In such a case, it is possible to provide an optical output control circuit that can automatically return to the original optical output level.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a light output control circuit according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a light output control circuit according to a second embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a light output control circuit according to a third embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of a conventional light output control circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical amplifier 2, 3 Optical splitter 4 Laser diode 5 Laser diode drive part 6 APC part 6a Operational amplifier 6b, 6h Analog switch 6c, 6d Feedback resistor 6e Electronic volume 6f, 6g Amplification circuit 7, 9, Photodiode 8, 10 Amplifier 11 Detection level amplification switching unit 11a Operational amplifier 11b, 11h Analog switch 11c, 11d Feedback resistor 11e Electronic volume 11f, 11g Amplification circuit 12 Optical connector disconnection detection unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/17 10/16

Claims (5)

[Claims] An optical amplifier for amplifying an optical signal; a driving unit for controlling an amplification degree of the optical amplifier; and an optical output detecting unit for converting a part of the optical signal output from the optical amplifier into an electric signal. Feedback control means for controlling the driving means so that the light output level of the optical amplifier becomes a predetermined level based on the output signal of the light output detection means; and reflection for converting reflected light from the light output side into an electric signal. Light detecting means, and comparing means for comparing an output signal of the light output detecting means and an output signal of the reflected light detecting means, wherein the comparing means is configured to output the feedback control means when an output level of the reflected light detecting means increases. To control the optical output level of the optical amplifier, and when the output level of the reflected light detecting means subsequently decreases, the feedback control means is controlled to control the optical power level. An optical output control circuit for controlling an optical output level of the width unit to the predetermined level. 2. The feedback control means includes an amplifier circuit having a variable amplification degree, and the comparison means reduces the amplification degree of the amplification circuit of the feedback control means when the output level of the reflected light detection means increases. Then, when the optical output level of the optical amplifier is decreased, and subsequently, the output level of the reflected light detecting means is decreased, the amplification degree of the amplifier circuit of the feedback control means is increased to reduce the optical output level of the optical amplifier to the predetermined level. 2. The light output control circuit according to claim 1, wherein the light output is controlled to a level. 3. The optical output control circuit according to claim 2, wherein the amplification circuit of the feedback control means has a configuration in which the amplification degree changes by switching a feedback resistor of the operational amplifier by a switch means. 4. The amplification circuit according to claim 2, wherein the amplification circuit of the feedback control means has a configuration in which the amplification degree is changed by switching a resistance value of a feedback resistor formed into an electronic volume of the operational amplifier. Light output control circuit. 5. The light according to claim 2, wherein the amplification circuit of the feedback control means has a configuration in which the amplification degree changes by switching the outputs of a plurality of amplification circuits having different amplification degrees by a switch means. Output control circuit.