JPH11162221A - Ase light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To notify an uncontrollable state by comparing output signal light detected by an output light monitor and a target value thereof to control excited light to be supplied from excited light supplying means to a light amplification optical fiber so as to reduce its difference, and outputting an abnormal signal if its difference is greater than a given value. SOLUTION: An output light level detected by an output light monitor 7 and an error signal from a comparator 11 to which a target value 10 thereof is inputted controls excited light of an excitation semiconductor laser 2 driven by a laser driving circuit 3. The excited light is injected into a light amplification optical fiber 1, and natural emitted light in which an output is constantly controlled is outputted. A control state signal of a control state detecting circuit 9 having a comparator and a resistor or the like where an error signal from a comparator 11 is an output of a high level when a control state is normal and an output of a low level when it is abnormal. Therefore, if a state of an output constant control is abnormal, danger of continuing operation in an unstable output state is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ASE light source device that monitors the output control state of a light source device that outputs spontaneous emission light (ASE light) using an optical amplification optical fiber.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional ASE light source device. Pumping light generated by the pumping semiconductor laser 35 driven by the drive circuit 36 is injected into the pumping optical fiber (EDF) 31 and output as ASE light according to the optical power of the pumping light. ASE from change of pumping light of pumping semiconductor laser due to temperature change and aging
Although the output of the light source device fluctuates, control for keeping the output constant (output constant control) is required. In order to control the output to be constant, it is realized by comparing the signal of the output signal light monitor with a target value which is a fixed value, and driving the semiconductor laser 35 for excitation with the error signal. Usually this ASE
The light has a spectrum having a wavelength of 1530 to 1560 nm and can be used as a light source.

[0003]

The conventional constant output control is a method of controlling the semiconductor laser for excitation so as to always keep the output signal light level constant. However, there is a limit to the output power of the semiconductor laser for pumping, and if an attempt is made to increase the target value of the output signal light, an uncontrollable state in which the output signal light is not emitted enough to keep the output signal level constant may occur. It is very important for the operation to know whether or not such an out-of-control condition has occurred.However, the conventional technology does not have such a function. And there is a danger that the operation will be continued without the output signal level being stabilized.
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide a means for knowing whether or not the control has fallen into an uncontrollable state and to have a function of notifying the state.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and the present invention is directed to supplying spontaneous emission light (ASE) by supplying excitation light to an optical amplification optical fiber from excitation light supply means.
And a target value for controlling an output signal light detected by an output light monitor for monitoring an output signal light of the ASE light source device, the target value and the detected output signal light. And a control circuit for controlling the pumping light from the pumping light supply means so as to reduce the difference between the output signal light compared with the target value and the target value. An ASE light source device configured to output an abnormal signal when a difference between the output signal light and the target value is larger than a certain value.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an ASE light source device according to a first embodiment of the present invention, and FIG. 2 is a block diagram of an ASE light source device according to a second embodiment of the present invention.
FIG. 3 is a detailed block diagram of a control state detection circuit used in the ASE light source device of the present invention. The ASE light source device of FIG. 1 includes an ASE light source device and an output light monitor 7 for monitoring output signal light. A target value 10 of the output signal light is input to a comparator 11 and detected by the output light monitor 7. By controlling the pumping light of the pumping semiconductor laser 2 with the error signal compared with the output signal light level, constant output control is realized. Further, the configuration is such that an error signal output from the comparator 11 is input to the control state detection circuit 9 so that the control state can be monitored. The output of the control state detection circuit 9 is a binary logic of a high level or a low level, and the control state signal, which is the output of the control state detection circuit 11 when the control state is normal, becomes a high level output. Is a low level output.

Next, the operation of the signal level detection circuit will be described with reference to FIG. The output light monitor signal, which is the output from the output light monitor 7, and the target value 10 are compared by a comparator 11, and the output is connected to the laser drive circuit 3. C1 is a capacitor for phase compensation of the constant output control loop. The output of the comparator 11 is connected to the control state detection circuit 9 and compared with the voltage V2 obtained by dividing Vcc by the resistors R5 and R6 by the comparator IC3. When the control state is operating normally, the input terminal voltages of the positive phase and the negative phase of IC1 become almost equal, and the voltage becomes V1. However, if V1 is the current I flowing through the semiconductor laser 2 for excitation, it is substantially equal to IR2. The current limiting resistor R1 is provided so that the current I is not more than the maximum allowable current Imax of the semiconductor laser 2 for excitation and not more than Imax.

When the output of the ASE light source device falls below the value set at the target value 10, the output light monitor signal is set to a voltage higher than the set voltage of the target value. Will also be higher. When the output voltage of the comparator 11 becomes equal to or higher than Imax.R2, the control state is abnormal, and the control state detection circuit 9 detects this state.

[0008] The output of the comparator 11 is connected to the comparator IC3 of the control state detection circuit 9 and compared with the voltage V2.
Since V2 = Imax · R2 is set,
When the output voltage of the comparator 11 is abnormal in the control state larger than V2, the control state signal output from the comparator IC3 becomes low level. Next, referring to FIG.
An example will be described. This is a configuration in which the output light monitor in the first embodiment is replaced with an excitation light monitor. An excitation light monitor 7 for monitoring the excitation light of the excitation semiconductor laser 2 is provided. A target value 10 of the excitation light is compared with the excitation light detected by the excitation light monitor 7 by a comparator 11 and an error signal is generated. The constant output control is realized by controlling the excitation light of the semiconductor laser 2 for use. Further, the configuration is such that an error signal output from the comparator 11 is input to the control state detection circuit 9 so that the control state can be monitored. The control state detection circuit 9 has the same configuration as that described in the first embodiment.

[0009]

As described above, according to the present invention, the output signal from the ASE light source device and its target value are compared by the comparator.
When the difference is greater than a certain value, the output control state of the ASE light source device constant output control is output as a signal that is considered to be abnormal, so that there is no danger of continuing operation with the output state being unstable. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ASE light source device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an ASE light source device according to a second embodiment of the present invention.

FIG. 3 is a detailed block diagram of a control state detection circuit used in the ASE light source device of the present invention.

FIG. 4 is a block diagram of a conventional ASE light source device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber for optical amplification 2 Semiconductor laser for excitation 3 Laser drive circuit 4 Isolator 5 Optical splitter 6 Output signal light 7 Output light monitor 8 Control state signal 9 Control state detection circuit 10 Target value 11 Comparator

Claims (2)

[Claims] 1. An ASE light source device which supplies excitation light to an optical fiber for optical amplification from excitation light supply means and outputs spontaneous emission light (ASE light). A comparing means for setting a target value for controlling the output signal light detected in the step (c) and comparing the target value with the detected output signal light; and the output signal light and the target value compared by the comparing means. And a control circuit for controlling the pumping light from the pumping light supply means so as to reduce the difference between the output signal light and the target value. A that outputs spontaneous emission light characterized by being output
SE light source device. 2. An ASE light source device for supplying excitation light to an optical fiber for optical amplification from excitation light supply means and outputting spontaneous emission light (ASE light), wherein the excitation light for monitoring the excitation light from said excitation light supply means. A comparison means for setting a target value for controlling the excitation light detected by the monitor and comparing the target value with the detected excitation light, and a comparison between the excitation light compared by the comparison means and the target value A control circuit for controlling the pumping light from the pumping light supply means so as to reduce the difference, and outputting an abnormal signal when the difference between the pumping light and the target value is larger than a certain value. ASE light source device for outputting spontaneous emission light characterized by the following: