JP2002094466A - Optical receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical receiver which can eliminate noise components from a returned light signal overlaid with noise, when amplifying the returned light signal. SOLUTION: The return light 25, overlaid with noise, is converted into a current signal by means of a photodiode 1 and then is converted into a voltage signal 9 by means of a current/voltage (I-V) conversion section 7. The voltage signal 9 is inputted into an inversing input terminal 4 of an operational amplifier 2 and at the same, is inputted also to a filter 8. The filter 8 extracts low-frequency noise components from the voltage signal and then inputs the components into a non-inverting input terminal 6. The operational amplifier 6 eliminates only the low-frequency in-phase noise components from the inputted signal and the conducts amplification operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical receiving device,
In particular, the present invention relates to an optical receiving device that receives return light from an optical output connector end connected to an optical transmission line and detects that the optical output connector has deviated from the optical transmission line.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional optical receiving apparatus for receiving return light from the end of an optical output connector connected to an optical transmission line and detecting the departure of the optical output connector from the optical transmission line.
As shown in FIG. 1, there is known an optical receiving device including an optical branching element 22a for branching return light from the optical output connector 23a, a photodiode 1a for converting the return light into an electric signal, and an operational amplifier 2a.

In the conventional optical receiver shown in FIG. 9, return light from the end of an optical output connector 23a is transmitted to an optical branching element 22a.
And is incident on the photodiode 1a. The photodiode 1a converts the return light into a current signal, and inputs this to the current / voltage converter 7a. Current / voltage converter 7a
Converts the input current signal into a voltage signal 9a,
This is input to the inverting input terminal 4a of the operational amplifier 2a.
The operational amplifier 2a amplifies the voltage signal 9a input to the inverting input terminal 4a with the amplification determined by the feedback resistor R. The conventional optical receiving device can detect the detachment of the optical output connector 23a from the optical fiber based on the signal amplified by the operational amplifier 2a.

[0004]

However, in the above-mentioned conventional optical receiver, an irregular noise component is superimposed on the return light from the end of the optical output connector 23a. When the signal is amplified by the operational amplifier 2a and the disconnection of the optical output connector 23a is detected, there is a fear that an erroneous detection may be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and an optical receiver capable of removing a noise component from a return optical signal on which noise is superimposed when amplifying the return optical signal. It is intended to provide.

[0006]

According to a first aspect of the present invention, there is provided an optical receiving apparatus for receiving return light from an optical output connector connected to an optical transmission line and performing photoelectric conversion. Return light receiving means, and extracting means for extracting a predetermined frequency component from the electric signal generated by the return light receiving means, and using the frequency component signal extracted by the extracting means, Removing means for removing frequency components.

The optical receiving apparatus according to a second aspect of the present invention is the optical receiving apparatus according to the first aspect, further comprising a signal adding means for adding a predetermined voltage to a signal of the frequency component extracted by the extracting means. The removing means removes the frequency component from the electric signal using the signal of the frequency component added by the signal adding means.

According to a third aspect of the present invention, in the optical receiving device according to the first or second aspect, the phase of the electric signal generated by the return light receiving unit and supplied to the removing unit, and Phase adjusting means for adjusting at least one phase so that the phase of the frequency component signal extracted by the extracting means matches.

Further, an optical receiving apparatus according to a fourth aspect is the optical receiving apparatus according to the first, second or third aspect, wherein the extracting means has a plurality of filters for extracting frequency components in different frequency bands. Then, a signal obtained by synthesizing the frequency components extracted by each filter is output.

In the optical receiving apparatus according to the present invention, the return light receiving means receives the return light from the optical output connector connected to the optical transmission line, photoelectrically converts the return light, and the extraction means includes:
A predetermined frequency component is extracted from the electric signal generated by the return light receiving unit, and the removing unit removes the frequency component from the electric signal using the signal of the frequency component extracted by the extracting unit. Therefore, when the frequency component extracted by the extraction means contains much noise, the noise can be removed from the electric signal by the removal means,
Detachment of the optical output connector from the optical transmission line can be stably detected without erroneous detection.

Further, in the optical receiving apparatus according to the second aspect, the signal adding means adds a predetermined voltage to the signal of the frequency component extracted by the extracting means, and the removing means removes the frequency component added by the signal adding means. , The frequency component is removed from the electric signal. Therefore, when the operational amplifier is used as the removing means, even if the power supply voltage of the operational amplifier is limited, the disconnection of the optical output connector from the optical transmission line can be detected stably without erroneous detection, and the system noise can be reduced. Since the influence can be reduced, the detachment can be detected more stably.

According to a third aspect of the present invention, in the optical receiving apparatus, the phase adjusting means includes a phase of the electric signal generated by the return light receiving means and a frequency component extracted by the extracting means, which are supplied to the removing means. So that the phases of the signals match
At least one phase is adjusted. Therefore, it is possible to improve the accuracy of removing noise components and the like superimposed on the voltage signal by the removing means, and to accurately measure the magnitude of the return light from the optical output connector. Detection can be performed more stably.

Further, in the optical receiving apparatus according to the fourth aspect,
The extracting means has a plurality of filters for extracting frequency components in different frequency bands, and outputs a signal obtained by synthesizing the frequency components extracted by each filter. Therefore, even if the return light from the optical output connector has noise in a wide frequency band, the removing means can remove such noise, so that the disconnection of the optical output connector can be detected more stably. it can. For example, in the case where there is a first filter for extracting a frequency component in a low frequency band and a second filter for extracting a frequency component in a high frequency band, the removing unit includes not only power supply noise (low frequency component) but also Noise (high-frequency components) generated from a processor or the like that operates with a high-speed clock can also be removed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of an optical receiver according to the present invention will be described with reference to [first embodiment], [second embodiment], [third embodiment], and [fourth embodiment]. Embodiment], [Fifth Embodiment], [Sixth Embodiment], and [Seventh Embodiment] will be described in detail in this order with reference to the drawings. The optical receiving device according to these embodiments receives return light from an optical output connector end connected to an optical transmission line such as an optical fiber, and disconnects the optical output connector from the optical transmission line based on the amount of received light. Is to be detected.

FIG. 1 shows a first embodiment of the present invention.
It is a lineblock diagram showing the optical receiving device concerning an embodiment. In the figure, an optical receiving apparatus according to the present embodiment includes an optical input connector 20 for inputting an optical signal, an optical amplifier 21 for amplifying the input optical signal, and an optical output connector 23 for outputting an optical signal.
And splits the optical signal amplified by the optical amplifier 21 and supplies it to the two optical output connectors 23.
A light splitting element 22 for splitting the return light from the photodiode, and in particular, the photodiode 1 corresponding to the return light receiving means, the current / voltage converter 7, and the operational amplifier 2 corresponding to the removing means. , A filter 8 corresponding to the extracting means
It is comprised including. In FIG. 1, reference numeral 24 denotes an optical signal amplified by the optical amplifier 21;
Reference numeral 5 denotes a return light signal obtained by branching the return light from the optical output connector 23 by the optical branching element 22. Reference numeral 4 denotes an inverting input terminal (-) of the operational amplifier 2, reference numeral 6 denotes a non-inverting input terminal (+), and reference numeral 5 denotes an output terminal.

First, the photodiode 1 receives a return optical signal branched by the optical branching element 22 and converts it into a current signal. Further, the current / voltage conversion unit 7
It converts a current signal from the photodiode 1 into a voltage signal. The voltage signal 9 converted by the current / voltage converter is input to the inverting input terminal 4 of the operational amplifier 2. The filter 8 extracts a low-frequency noise component from a voltage signal 9 representing a return light signal on which a noise component is superimposed. The extracted low frequency noise component signal is supplied to the operational amplifier 2
Is input to the non-inverting input terminal 6. Further, the operational amplifier 2 is a differential amplifier circuit that amplifies the difference between the voltage signal 9 input to the inverting input terminal 4 and the signal of the low-frequency noise component input to the non-inverting input terminal 6. Is determined by the feedback resistor R.

The operation of the optical receiver according to the present embodiment will be described below. It is assumed that a noise component is superimposed on the return optical signal 25 from the optical output connector 23 due to the connection state of the optical output connector 23 to the external optical connector, a change in the amount of light reflection attenuation at the end of the optical output connector 23, or the like. I do. The return light signal 25 is converted to a current signal by the photodiode 1, and is converted to a voltage signal 9 by the current / voltage converter 7. The voltage signal 9 is input to the inverting input terminal 4 of the operational amplifier 2 and to the filter 8. The filter 8 extracts a low frequency noise component of the voltage signal 9 and inputs the extracted low frequency noise component to the non-inverting input terminal 6 of the operational amplifier 2. After removing only the low frequency noise component from the voltage signal 9 input to the inverting input terminal 4, the operational amplifier 2 amplifies the signal.

As described above, in the optical receiver of this embodiment, only the low-frequency noise component is extracted from the return optical signal 25 (voltage signal 9) by the filter 8, and the operational amplifier 2 returns the return optical signal 25 (voltage signal 9). Since the signal obtained by removing the low frequency noise component signal extracted by the filter 8 from 9) is output, the signal is not much affected by noise, and the disconnection of the optical output connector 23 can be stably detected without erroneous detection. be able to.

The filter 8 of the present embodiment is a so-called low-pass filter (Low Pa filter) for extracting low-frequency noise components.
ss Filter: LPF), but a high-pass filter that extracts high-frequency noise components (High Pass Filter: HPF)
It may be. Further, the filter 8 may be configured such that a plurality of filters having different passband characteristics of noise are connected in parallel. For example, as shown in FIG. 2, the filter 8 includes a filter 8a having a low-frequency characteristic and a filter 8b having a high-frequency characteristic, and a noise component extracted by the filter 8a and a noise component extracted by the filter 8b are: After being combined, it is input to the non-inverting input terminal 6 of the operational amplifier 2. Therefore, even if the return optical signal 25 has noise components in a wide frequency band, the operational amplifier 2 can remove these noise components from the return optical signal 25 (voltage signal 9).

[Second Embodiment] FIG. 3 shows a second embodiment of the present invention.
It is a lineblock diagram showing the optical receiving device concerning an embodiment. In the figure, the same reference numerals are given to the same parts as those in FIG. 1 (first embodiment), and the description is omitted. The optical receiving device according to the present embodiment is configured to further include a signal adding unit 10 corresponding to a signal adding unit in claims, in addition to the components included in the optical receiving device according to the first embodiment. The signal adder 10 adds the reference voltage Vb to the signal of the low frequency noise component extracted by the filter 8 and adds this signal to the operational amplifier 2.
Is input to the non-inverting input terminal 6. The operational amplifier 2 of the present embodiment removes noise of the voltage signal 9 using the signal from the signal adding unit 10 and amplifies and outputs the voltage signal from which the noise has been removed.

As described above, in the optical receiver according to the present embodiment, the signal adding section 10 adds the reference voltage Vb to the signal of the low-frequency noise component, and this signal is used for removing the noise component in the operational amplifier 2. Therefore, even when the power supply voltage of the operational amplifier 2 is limited, the disconnection of the optical output connector 23 can be stably detected without erroneous detection, similarly to the optical receiver of the first embodiment. further,
Since the influence of system noise in addition to the noise superimposed on the return light signal 25 can be avoided, the detachment of the optical output connector 23 can be detected more stably.

[Third Embodiment] FIG. 4 shows a third embodiment of the present invention.
It is a lineblock diagram showing the optical receiving device concerning an embodiment. In the figure, the same reference numerals are given to the same parts as those in FIG. 1 (first embodiment), and the description is omitted. The optical receiver according to the present embodiment is configured to further include a phase adjuster 11 corresponding to a phase adjuster according to the claims, in addition to the components included in the optical receiver according to the first embodiment. The phase adjuster 11 adjusts the phase of the voltage signal 9 so that the phase of the noise component superimposed on the return light signal 25 matches the phase of the low-frequency noise component signal extracted by the filter 8. is there. The signal output from the phase adjustment unit 11 is input to the inverting input terminal 4 of the operational amplifier 2.

As described above, in the optical receiver of this embodiment, the phase of the noise component superimposed on the voltage signal 9 input to the inverting input terminal 4 of the operational amplifier 2 and the low level input to the non-inverting input terminal 6 Since the phase of the frequency noise component matches, the accuracy of removing the noise component superimposed on the voltage signal 9 in the operational amplifier 2 can be improved. Therefore, the detachment of the optical output connector 23, which can accurately measure the magnitude of the return light signal 25, can be detected more stably.

Note that, as shown in FIG.
May be provided on the output side of the filter 8. At this time, the phase adjustment unit 11 determines that the phase of the noise component superimposed on the return optical signal 25 matches the phase of the signal of the low-frequency noise component extracted by the filter 8, ie, the non-inverting input terminal 6 and the inverting signal. The phase of the low-frequency noise component signal extracted by the filter 8 is adjusted so that the phase of the noise component matches between the input terminals 4. Therefore, the noise component removal accuracy in the operational amplifier 2 can be improved, and the disconnection of the optical output connector 23 can be more stably detected as described above.

[Fourth Embodiment] FIG. 6 shows a fourth embodiment of the present invention.
It is a lineblock diagram showing the optical receiving device concerning an embodiment. In the same figure, the same reference numerals are given to the same parts as those in FIG. 3 (second embodiment), and the description is omitted. The optical receiver according to the present embodiment includes the phase adjuster 11 described in the third embodiment in addition to the components included in the optical receiver according to the second embodiment.
Is further provided. In this embodiment,
The phase adjuster 11 is provided on the inverting input terminal 4 side of the operational amplifier 2 and has a phase of a noise component superimposed on the return optical signal 25 and a low frequency noise component extracted by the filter 8 and superimposed with the reference voltage Vb. The phase of the voltage signal 9 is adjusted so that the phase of the voltage signal 9 matches the phase of the noise component between the non-inverting input terminal 6 and the inverting input terminal 4.

Therefore, the effect provided by the optical receiver of the second embodiment is that the disconnection of the optical output connector 23 is stably detected without erroneous detection even when the power supply voltage of the operational amplifier 2 is limited. And the effect of the optical receiver of the third embodiment, that is, the effect of improving the accuracy of removing the noise component superimposed on the voltage signal 9 can be achieved at the same time.

As shown in FIG. 7, the phase adjuster 11
Is provided on the non-inverting input terminal 6 side of the operational amplifier 2 so that the phase of the noise component superimposed on the return optical signal 25 and the filter 8
The phase of the signal of the low-frequency noise component may be adjusted so that the phase of the signal of the low-frequency noise component on which the reference voltage Vb is superimposed matches the phase of the signal of the low-frequency noise component. Also at this time, the effect of the optical receiving device of the second embodiment and the effect of the optical receiving device of the third embodiment can be simultaneously achieved.
As shown in FIG. 8, the filter 8, the phase adjuster 11, and the signal adder 1 adjust the phase of the signal of the low-frequency noise component extracted by the filter 8 and superimpose the reference voltage Vb.
It may be arranged in the order of 0, and the same effect as above can be obtained.

[0028]

As described above, in the optical receiver according to the present invention, the return light receiving means receives the return light from the optical output connector connected to the optical transmission line and performs photoelectric conversion.
In the extracting means, a predetermined frequency component is extracted from the electric signal generated by the return light receiving means, and in the removing means,
The frequency component is removed from the electric signal using the signal of the frequency component extracted by the extracting means. Therefore, if the frequency component extracted by the extraction means contains a lot of noise, the noise can be removed from the electric signal by the removal means, so that the optical output connector can be safely removed from the optical transmission line without erroneous detection. And can be detected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an optical receiving device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an optical receiving device provided with a plurality of filters having different band characteristics.

FIG. 3 is a configuration diagram illustrating an optical receiving device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating an optical receiving device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing another form of the optical receiver according to the third embodiment of the present invention.

FIG. 6 is a configuration diagram illustrating an optical receiving device according to a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram showing another mode of the optical receiver according to the fourth embodiment of the present invention.

FIG. 8 is a configuration diagram showing another embodiment of the optical receiver according to the fourth embodiment of the present invention.

FIG. 9 is a configuration diagram showing a conventional optical receiving device.

[Explanation of symbols]

 Reference Signs List 1 photodiode 2 operational amplifier 4 inverting input terminal 5 output terminal 6 non-inverting input terminal 7 current / voltage converter 8, 8a, 8b filter 9 voltage signal 10 signal adding unit 11 phase adjusting unit 20 optical input connector 21 optical amplifying unit 22 light Branch element 23 Optical output connector 25 Return optical signal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04B 10/08 17/00 F term (Reference) 5K002 AA03 BA04 CA02 CA12 EA03 FA01 5K042 CA10 CA12 CA16 DA13 FA06 FA25

Claims (4)

[Claims] 1. A return light receiving means for receiving return light from an optical output connector connected to an optical transmission line and performing photoelectric conversion, and extracting a predetermined frequency component from an electric signal generated by the return light reception means. Extraction means, using the frequency component signal extracted by the extraction means,
An optical receiver comprising: a removing unit configured to remove the frequency component from the electric signal. 2. A signal adding means for adding a predetermined voltage to the signal of the frequency component extracted by the extracting means, wherein the removing means uses the signal of the frequency component added by the signal adding means, The optical receiving device according to claim 1, wherein the frequency component is removed from the electric signal. 3. A phase of an electric signal supplied to said removing means, generated by said return light receiving means, and a phase of a signal of a frequency component extracted by said extracting means are matched.
3. The optical receiving device according to claim 1, further comprising a phase adjusting unit that adjusts at least one phase. 4. The apparatus according to claim 1, wherein said extracting means has a plurality of filters for extracting frequency components in different frequency bands, and outputs a signal obtained by combining the frequency components extracted by each filter. 4. The optical receiver according to 2 or 3.