JPH05227094A - Light receiver - Google Patents

Abstract

PURPOSE:To prevent a faulty operation of the past-stage equipment, confused maintenance, or adverse effect on the normal line due to the noise outputted in this state by interrupting the output signal to the post-stage device when the optical input signal from the transmission line is interrupted or deteriorated. CONSTITUTION:The optical input signal from a transmission line is branched into two by an optical divider 1. The branching output is inputted into a control amplifier section 2. The section 2 inputs an optical signal to output an electric signal at the constant level. Another branching output is inputted to an input light power detector 3. In this case, the disconnection of an input signal or the light power close to the disconnection value is detected. The output signal from the section 2 is inputted to a buffer 4, interrupting the passage of the input signal by means of the detection signal from the input light power detector 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical receiver, and more particularly to an optical receiver which receives an optical signal from a transmission line, converts it into an electric signal and amplifies it.

[0002]

2. Description of the Related Art Conventionally, an optical receiver of this type has the structure shown in FIG. The optical signal from the transmission line is input to the light receiving element 21 and converted into an electric signal here. This electric signal is amplified by the preamplifier 22 and the variable gain amplifier 23 and output to the subsequent device. Part of this output signal is input to the peak detector 24, where the amplitude of the output signal is detected, and the detected signal is amplified by the DC amplifiers 25 and 26 and input to the multiplication factor controller 27. The output of the DC amplifier 25 is also input to the gain control terminal of the variable gain amplifier 23. The output signal of the variable gain amplifier 23 is the multiplication factor controller 2
By controlling the multiplication factor of the light receiving element 21 by 7 and the gain control of the variable gain amplifier, it is controlled so as to maintain a constant level even if the optical power of the optical input signal from the transmission line fluctuates.

[0003]

As described above, in the conventional example, since the level of the output signal is controlled to be constant, when the optical power of the optical input signal decreases, the multiplication factor of the light receiving element increases, In addition, the gain of the variable gain amplifier is controlled to increase. When the optical power of the optical input signal is cut off or decreases close to this, the multiplication factor and the gain become maximum. In this state, the light receiving element emits a huge amount of noise, and the variable gain amplifier amplifies and outputs it with the maximum gain. This noise causes problems such as malfunctions, confusion in maintenance, and adverse effects on normal lines in subsequent devices.

[0004]

An optical receiver according to the present invention has a demultiplexer for branching an optical input signal from a transmission line into two and an optical output signal of the demultiplexer is input to a predetermined level. A control amplification unit that outputs a stabilized electric signal, and an input optical power detector that inputs the other optical output signal of the demultiplexer and detects optical power that is equal to or less than a predetermined value of this input signal, And a buffer for inputting the output electric signal of the control amplification unit and controlling the passage rate of the input signal by the detection signal of the input optical power detector.

[0005]

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. An optical input signal from the transmission line is branched into two by the optical demultiplexer 1, and the branched output is input to the control amplification unit 2. The control amplification unit 2 is equivalent to the optical receiver shown in FIG. 2, and inputs an optical signal and outputs an electric signal stabilized at a constant level. The other branch output of the optical demultiplexer 1 is input to the input optical power detector 3, which detects the interruption of the input signal or the optical power of a value close to this. The output signal of the control amplifier 2 is input to the buffer 4, where the detection signal from the input optical power detector 3 controls the passage of the input signal.

That is, when the optical input signal from the transmission line is cut off or drops to a value close to this, the input optical power detector 3 detects this and outputs a detection signal. The detection signal blocks the output signal of the control amplification unit 2 from passing through the buffer 4 and prevents the output signal from being sent to the subsequent device.

[0007]

As described above, according to the present invention, when the optical input signal from the transmission line is cut off or drops to a value close to this, the output signal to the succeeding device is cut off. You don't have to send the output to subsequent devices.
Therefore, there is an effect of preventing the occurrence of malfunction, confusion in maintenance, and bad influence on the normal line in the subsequent device.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an example.

[Explanation of symbols]

 1 Optical demultiplexer 2 Control amplifier 3 Input optical power detector 4 Buffer

Claims (1)

[Claims] 1. A demultiplexer for branching an optical input signal from a transmission line into two, and a control amplification section for inputting the optical output signal of the demultiplexer and outputting an electric signal stabilized at a predetermined level. And an input optical power detector for inputting the other optical output signal of the demultiplexer and detecting an optical power of the input signal equal to or less than a predetermined value, and inputting an output electric signal of the control amplification section. An optical receiver, comprising: a buffer for controlling a transmission rate of an input signal by a detection signal of the input optical power detector.