JPH05199185A - Light direct amplifier repeater - Google Patents

Abstract

PURPOSE:To provide the light direct amplifier repeater capable of detecting the interruption of the light input signals only by adding a simple circuit. CONSTITUTION:This system having a light amplifier section 130 amplifying the I/O light signal excited by the output light from a light source 190 for excitation, a light source driving section 180 driving the light source for excitation, and a light source 190 for excitation is provided with a light branching section 120 branching light signals to be inputted to the light amplifier section 130, average value detection section 160 outputting the average value of the input signals after the branched output light of the light branching section 120 is inputted and converted into an electric signal, and a signal interruption discriminating section 170 comparing the average value of the output of the average value detection section 160 with the set reference value and when the average value becomes less than the reference value, discriminating the interruption of the input signal and outputting control signals to stop the driving of the light source 190. Thus, the output of the light source 190 is stopped at the interruption of the input signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical direct amplification repeater for directly amplifying an optical signal, and more particularly to an input signal disconnection detection circuit.

In an optical communication system using an optical direct amplification repeater, if the optical input signal to the optical direct amplification repeater is cut off, if left unattended, noise is amplified by the optical output stabilizing circuit, and it is transmitted to the subsequent stage. An erroneous optical signal will be transmitted to the connected optical direct amplification repeater, etc., and it is difficult to obtain an accurate result especially in a loopback test. Therefore, in the optical direct amplification repeater, the disconnection of the optical input signal is detected. In this case, an optical direct amplification repeater capable of detecting the disconnection of the optical input signal only by adding a simple circuit is desired. ing.

[0003]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of a conventional optical regenerator. Fig. 4 shows so-called 3R functions (Reshaping, Retiming, Regeneratin) that have been used conventionally.
The configuration of the optical regenerator having g) is shown. In the figure, when an optical signal is received from an optical transmission line, it is converted into an electric signal by a photodiode (hereinafter referred to as PD) 1 and then an equalization amplification unit 2 Amplifies the pulse signal that has been attenuated and deteriorated to the extent that the presence or absence of a pulse can be determined (Reshaping function). Then, the output is branched and added to the identification reproduction unit 3 and the non-linear clock extraction unit 6 in the timing circuit.

A nonlinear clock extraction unit 6 differentiates the rising and falling portions of the input signal and outputs a signal having a differentiated waveform, which is added to a bandpass filter (hereinafter referred to as BPF) 7 and only the frequency component of the main signal is extracted. And output. The sine wave signal output from the BPF 7 is amplified by the amplifier 8 and then converted into a pulse waveform clock signal by the limiter amplifier 9,
In addition to the above-mentioned identification reproducing section 3 (timing function).

The identification reproduction section 3 performs identification reproduction on the signal input from the equalization amplification section 2 by the above-mentioned clock signal (Regenerating function), and outputs the output signal of the identification reproduced pulse to the laser diode drive section (hereinafter referred to as a laser diode drive section). In addition to the LD driving unit 4), the LD 5 is driven by this signal to be converted into an optical signal and transmitted to the optical transmission line (optical fiber).

On the other hand, the sine wave signal output from the amplifier 8 is branched and added to the peak detection section 10 in the input signal break detection circuit to detect the peak voltage value of the input sine wave signal. Then, the comparator 11 compares this peak voltage value with a preset reference voltage (Vref), outputs an output cutoff signal when the peak voltage value is smaller than the reference voltage (Vref), and outputs it to the LD drive unit 4 described above. In addition, stop driving the LD5.
In this way, the input signal disconnection is detected in the optical direct amplification repeater having the 3R function.

[0007]

However, in the optical direct amplification repeater having no timing circuit, there is a problem that the above-mentioned method of detecting the input signal loss cannot be used.

Therefore, an object of the present invention is to provide an optical direct amplification repeater capable of detecting an optical input signal break by simply adding a simple circuit.

[0009]

The above problems can be solved by the structure of the circuit shown in FIG. That is, in FIG. 1, an optical amplification unit 130 that is excited by the output light of the excitation light source 190 and amplifies and outputs an input optical signal, a light source drive unit 180 that drives the excitation light source 190, and a light source drive unit. In the optical direct amplification repeater having a light source 190 for pumping, which is driven by the section 180 and outputs light for pumping the optical amplifier 130, 120 is an optical branch for branching an optical signal input to the optical amplifier 130. It is a department.

Reference numeral 160 denotes an average value detection unit that receives the output light branched by the optical branching unit 120, converts it into an electric signal, and then calculates and outputs the average value of the input signal. 170 is the average value detector 16
Compare the average value of the output of 0 and the preset reference value,
When the average value becomes smaller than the reference value, it is determined that the input signal is disconnected, and a signal disconnection determination unit that outputs a control signal for stopping the driving of the excitation light source 190 to the light source drive unit 180.

Then, when the input signal is cut off, the light source for excitation 19
Configure to turn off 0 output.

[0012]

In FIG. 1, the average value detecting section 160 is provided with an optical branching section.
After the 120 branched output lights are input and converted into electric signals, an average value of the input signals is obtained and output using, for example, a low-pass filter.

This average value is added to the signal disconnection judging section 170 and compared with a preset reference value. Then, when the average value becomes smaller than the reference value, it is determined that the input signal is disconnected, and the excitation light source is used.
A control signal for stopping the driving of 190 is output to the light source driving unit 180, and the output of the excitation light source 190 is stopped.

As a result, in the optical direct amplification repeater,
The conventional high-speed electric circuit becomes unnecessary, and the signal disconnection detection can be realized only by adding a simple circuit.

[0015]

2 is a block diagram showing the construction of an optical direct amplification repeater according to a first embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of an optical direct amplification repeater according to the second embodiment of the present invention. The same reference numerals denote the same objects throughout the drawings.

In FIG. 2, an optical signal input from an optical transmission line (optical fiber) is branched by an optical coupler 12, one of them is added to an erbium-doped fiber amplifier 13, and the other is newly provided input signal loss detection. Add to PD (photodiode) 15 in the circuit. In the erbium-doped fiber amplifier 13, a wavelength division multiplexer (hereinafter referred to as WDM)
The erbium-doped fiber amplifier 13 itself is excited by the optical power of the output of the LD 19 for excitation applied via 14, and the optical signal at the input is amplified and output.

On the other hand, when an optical signal is input to the PD 15 in the input signal disconnection detection circuit, it is converted into an electric signal and then the output is formed by a parallel combination of a resistor R and a capacitor C. In addition to (16), it outputs a voltage value Vo proportional to the average power of the input optical signal. This voltage value Vo is applied to one input terminal of the comparator 17, and compared with the threshold voltage value Vth preset by the comparator 17, and when the voltage value Vo becomes smaller than the threshold voltage value Vth, the optical input signal is disconnected. To determine. And at this time, LD for excitation
L control signal (output disconnection signal) to stop the optical output of 19
D drive unit 18 is added. When the LD drive unit 18 receives this control signal (output disconnection signal), it stops driving the LD 19 for excitation described above.

When the input signal disconnection detection circuit does not detect the disconnection of the optical input signal, nothing is output from the comparator 17,
The LD drive unit 18 drives the pumping LD 19, and the LD 19 continues to output the optical power for pumping the erbium-doped fiber amplifier 13.

As a result, in the optical direct amplification repeater,
The conventional high-speed electric circuit becomes unnecessary, and the input signal disconnection detection circuit can be realized only by adding the resistor R, the capacitor C, and the DC circuit (comparator).

Next, a second embodiment will be described with reference to FIG. FIG. 3 shows the structure of an optical direct amplification repeater that directly amplifies an input optical signal by an LD 21 and outputs the optical signal. The input optical signal is branched by an optical coupler 12 and one of them is set to L
In addition to D21, the other is added to PD15 in the input signal disconnection detection circuit as in the case of the first embodiment.
The LD 21 normally amplifies and outputs the input optical signal by the drive voltage (or current) from the LD drive unit 20.

On the other hand, in the PD 15 described above, after converting the optical signal into an electric signal, the voltage value Vo proportional to the average power of the input optical signal is obtained in addition to the LPF 16 constituted by the resistor R and the capacitor C. This voltage value Vo is applied to one input terminal of the comparator 17, and this voltage Vo is compared with the threshold voltage value Vth applied to the other input terminal. When the voltage value Vo is smaller than Vth, the input signal is disconnected. Then, a signal for disconnecting the output is added to the LD drive unit 20. When the LD drive unit 20 receives this output disconnection signal, it stops driving the LD 21 and
21 stops emitting light.

As a result, in the second embodiment, as in the case of the first embodiment, the optical direct amplification repeater does not require the conventional high-speed electric circuit, and the resistor R, the capacitor C, and The input signal disconnection detection circuit can be realized simply by adding a DC circuit (comparator).

The input signal disconnection detection circuits of the first and second embodiments of the present invention can be applied to the optical regenerator described in the prior art.

[0025]

As described above, according to the present invention, in the optical direct amplification repeater, the conventional high-speed electric circuit is not required, and the input signal disconnection detection can be performed by adding a simple circuit. Can be realized.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention,

FIG. 2 is a block diagram showing a configuration of an optical direct amplification repeater according to a first embodiment of the present invention,

FIG. 3 is a block diagram showing a configuration of an optical direct amplification repeater according to a second embodiment of the present invention,

FIG. 4 is a block diagram showing a configuration of a conventional optical regenerator.

[Explanation of symbols]

Reference numeral 120 is an optical branching unit, 130 is an optical amplifying unit, 160 is an average value detecting unit, 170 is a signal disconnection determining unit, 180 is a light source driving unit, and 190 is a pumping light source.

Claims (1)

[Claims] 1. An optical amplifier section (130) for amplifying and outputting an input optical signal by being excited by the output light of a pumping light source (190).
A light source drive unit (180) for driving the excitation light source,
In an optical direct amplification repeater having a pumping light source (190) that is driven by the light source driver and outputs light for pumping the optical amplifier, an optical signal to be input to the optical amplifier is branched. Optical branch (12
0), an average value detection unit (160) that inputs and outputs the branched output light of the optical branching unit, calculates an average value of the input signal, and outputs the average value detection unit. Is compared with a preset reference value, and when the average value becomes smaller than the reference value, it is determined that the input signal is cut off, and the driving of the excitation light source (190) is stopped. An optical signal characterized by being provided with a signal disconnection determination unit (170) that outputs a control signal to the light source drive unit (180), and stopping the output of the excitation light source (190) when the input signal is disconnected. Direct amplification repeater.