JPH0669168B2 - Switching the optical line without interruption - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for switching a line portion of a switching target section in a working optical line to a switching optical line without interruption.

"Prior art" As is known, tens of percent or more of the communication cables in urban areas have experienced changes to the laying route due to obstacles to this, or due to relocation, there is a high demand for switching to detour routes. .

By the way, when the working optical line is switched, the working information transmission should not be hindered, and therefore, line switching without interruption is required.

A novel method shown in FIGS. 8 to 10 has been proposed as such a hitless switching method.

The method will be briefly described below.

In FIG. 8, the working optical line 1 consisting of an optical cable is
It is laid across one station and the other station (not shown).

A beam splitter 2 required for line switching is inserted at each connection point of the optical line 1, and therefore the beam splitters 2 are located at both ends of the section line portion 1x to be switched of the active optical line 1.

Further, the variable optical attenuator 3 is inserted in the section line portion 1x.

In the above, if the beam splitter 2 is simply inserted at the connection point of the working optical line 1, an insertion loss of 3 dB occurs,
In order to reduce or eliminate this, a folding terminal 4 is connected to the beam splitter 2.

Further, a variable optical attenuator 5 is inserted in the folding terminal 4.

The return terminal 4 does not affect the current information signal by keeping it short.

By the way, the transmission speed of light in the optical cable is as high as 100 Mbps, and the 1 pulse width at this time is 2 m,
When the difference in optical path length exceeds the one pulse width, a bit error occurs.

Therefore, in FIG. 9, when the switching optical line 6 is connected across the beam splitters 2 at both ends of the section line portion 1x and the section line portion 1x is switched to the switching optical line 6 without interruption, these sections are The phase difference caused by the optical path length difference between the line portion 1x and the switching optical line 6 must be compensated.

Therefore, the following measures are taken in FIG.

That is, in FIG. 9, the switching optical line 6 connected as described above is provided with a variable optical attenuator 7, a variable optical wavelength transmission type optical filter 8 and a variable delay device 9.

Further, the folding terminal 4 is separated from each beam splitter 2, and one beam splitter 2 has an electric / optical converter.
10, a pulse generator 11 is connected, and an optical / electrical converter 12 and a pulse motor 13 are connected to the other beam splitter 2.

At this time, as the optical filter 8, a filter that does not transmit the currently used wavelength is used.

Then, an optical signal having a wavelength other than the working wavelength is sent from the pulse generator 11, the phase difference of the optical signal passing through the predetermined system is measured by the pulse monitor 13, and the phase difference is compensated by the variable delay device 9.

Next, the optical filter 8 is replaced with a working wavelength transmission type to disconnect the switching target section line section 1x, and further, the electric / optical converter 10, the pulse generator 11, the optical / electrical converter 12, the pulse monitor 13, etc. After removing the above, the return terminal 4 is connected to each beam splitter 2, and the predetermined non-interruption switching is completed in the state of FIG.

[Problems to be Solved by the Invention] In the method shown in FIGS. 8 to 10, the cost is high because the beam splitter 2 needs to be inserted at each connection point of the working optical line 1, and the beam splitter 2 has four side surfaces. Since the rod lens is arranged in the space, the space of the connecting portion becomes large.

In addition, the optical filter 8 is provided on the switching optical line 6 after the switching is completed.
Since the variable delay device 9 and the like remain, this also causes a cost increase, and extra connection loss occurs in the optical line 6 due to these remaining devices.

In view of the above-mentioned problems, the present invention provides a method for switching the optical line without interruption, which has a small additional cost and does not cause a change in connection loss due to switching.

[Means for Solving the Problems] In order to achieve the intended purpose, the present invention has a plurality of section line parts which are optically connected between these adjacent terminals with a separation interval interposed therebetween. A method for switching the section line section to be switched in the optical line in the order of the temporary optical line and the switching optical line, and at the time of predetermined optical line switching, an optical pulse generating means and an optical wavelength position A means for measuring the phase difference, a variable delay device for compensating for the phase difference, a working wavelength optical transmission type optical filter, a working wavelength non-transmission type optical filter, and a desorption of these optical filters. Is a method using a variable optical attenuator and a beam splitter, wherein a temporary optical line is provided with a variable delay device and a variable optical attenuator, and a switching optical line is also provided with a variable optical attenuator. That is the way Characterize.

Moreover, the method of the present invention includes, as the first switching step, between the light incident terminal of the section line portion to be switched and the light emission terminal of the section line section adjacent thereto, and of the section line section to be switched. Insert a beam splitter between the light output terminal and the light input terminal of the section line section adjacent to it, and install a temporary optical line in which a working wavelength optical opaque optical filter is inserted in the variable optical attenuator. After connecting to these beam splitters, connecting the optical pulse generating means to one beam splitter and connecting the phase difference measuring means to the other beam splitter respectively, switch the optical signal of different wavelength to the working wavelength light from the optical pulse generating means. While transmitting to the target section line section and the temporary optical line, the optical signals of the different wavelengths transmitted through the section line section and the temporary optical line are measured by the phase difference measuring means, and The difference is compensated by the variable delay device attached to the temporary optical line, and then the working wavelength light non-transmissive type optical filter inserted in the variable optical attenuator of the temporary optical line is used. And the optical signal of the working wavelength is also transmitted to the temporary optical line.In the next switching step, the section line section to be switched is removed from the working optical line between both beam splitters, and After connecting the switching optical line in which a non-transmissive optical filter is inserted in the variable optical attenuator to the place where the section line section to be switched is removed, an optical signal of a different wavelength from the working wavelength light is connected. While transmitting from the optical pulse generation means to the temporary optical line and the switching optical line,
The optical signals of the different wavelengths transmitted through the temporary optical line and the switching optical line are measured by the phase difference measuring means, and the phase difference is compensated by the variable delay device attached to the temporary optical line, and then the switching is performed. Replace the working wavelength optical non-transmissive type optical filter inserted in the variable optical attenuator of the working optical line with the working wavelength optical transmitting type optical filter and transmit the working wavelength optical signal to the switching optical line. Then, as the subsequent switching process, the temporary optical line, the beam splitter, the optical pulse generating means,
It is characterized in that the phase difference measuring means is removed from the working optical line.

[Examples] Examples of the method of the present invention will be described below with reference to the drawings.

FIG. 1 shows a working optical switching line 20 in the present invention.

The working optical switching line 20 is composed of an optical cable and is laid across one station and the other station (not shown).

Each connection point of the optical line 20, that is, the section line portions 20L, 2
Rod lenses 21a, 21b, 21c, on both ends of 0M, 20N ...
21d ... are respectively attached, and rod lenses 21a and 21b and 21c and 21d adjacent to each other are opposed to each other with an appropriate interval.

Further, a variable optical attenuator 22 to which an optical filter is attachable / detachable is inserted in each section line portion (see 20M).

In the working optical line 20, for example, when the section line section 20M is switched to a switching line described later, the section line section 20M
As shown in FIG. 2, beam splitters 23M and 23N are inserted between the rod lenses 21b and 21c at both ends of the rod lens 21a and 21d adjacent to the rod lenses 21b and 21c, respectively. From each beam splitter 23M, 2
Rod lenses 21e, 21f, 21g, and 21h are arranged corresponding to 3N.

Next, a temporary optical line having a variable optical attenuator 24 and a variable delay device 25 in which an optical filter that does not transmit the working wavelength is inserted.
As shown in FIG. 3, 26 is connected over the rod lenses 21e and 21f, the remaining rod lens 21g is connected to the electric / optical converter 27 and the pulse generator 28, and the remaining rod lens 21h is connected. Is connected to an optical / electrical converter 29 and a pulse monitor 30.

After that, the amount of attenuation of the temporary optical line 26 is kept to a minimum via the variable optical attenuator 24, and an optical signal of a wavelength different from the working wavelength is transmitted from the pulse generator 28 to the electrical / optical converter 27 via the section line. The phase difference between the pulses transmitted to the section 20M and the temporary optical line 26 and transmitted through the section line section 20M, the temporary optical line 26, and the optical / electrical converter 29 is measured by the pulse monitor 30, and the phase difference is measured. It is compensated through the variable delay device 25.

After compensating for the phase difference in this way, the optical filter inserted in the variable optical attenuator 24 is replaced with a working optical wavelength transmitting type to minimize the amount of attenuation of the temporary optical line 26.

By doing so, the optical signal of the working wavelength is also transmitted to the temporary optical line 26.

On the other hand, the section line section 20M to be switched has its attenuation amount maximized through the variable optical attenuator 22 as shown in FIG. 4 to make the light of the working wavelength impermeable, and then the working optical line 20 Separated from.

At this point, the non-instantaneous switching by the temporary optical line 26 of the section line portion 20M ends.

Next, as shown in FIG. 5, a switching optical line having a variable optical attenuator 40 in which an optical filter which does not transmit an optical signal of a working wavelength is inserted in the line and rod lenses 41b and 41c at both ends thereof.
42 is connected across the beam splitters 23M and 23N,
Similarly to the above, after the phase difference between the temporary optical line 26 and the switching optical line 42 is measured and compensated by an optical signal having a wavelength different from the working wavelength, the working wavelength optical non-transmissive optical filter is used to shift the working wavelength optical non-transmissive type optical filter. The attenuation amount of the switching optical line 42 is kept to a minimum via the variable attenuator 40 exchanged with the optical filter of (1), whereby the optical signal of the working wavelength is transmitted to the switching optical line 42.

After that, the temporary optical line 26 maximizes the amount of attenuation of the temporary optical line 26, and is separated from between the beam splitters 23M and 23N in a state where the light of the working wavelength is not transmitted.
7, pulse generator 28, optical / electrical converter 29, pulse monitor 3
0, the beam splitters 23M, 23N, etc. are also disconnected, and thus the state of FIG. 6 in which the predetermined non-instantaneous interruption switching is completed, that is, the state equivalent to that of FIG. 1 is obtained.

The above-mentioned variable optical attenuator may be any one that is configured so that the connection distance can be changed by using a V-groove connector and that an optical filter can be inserted between the connection parts.

As an example of the variable delay device, as shown in FIG. 7, a variable delay device having a slidable input side optical fiber 43, an output side optical fiber 44, a reflection mirror 45 for multiple reflection, and the like can be given.

[Effects of the Invention] As described above, in the case of the method of the present invention, after connecting the temporary optical line that bypasses the section line section over both ends of the section line section to be switched, the section line to be switched By removing the section and connecting the switching optical line to the section, and then removing the temporary optical line, it is possible not only to perform the predetermined non-interruptible switching, but also to change the optical line situation before and after the line switching. In addition, no expensive optical parts remain in the switched optical line, and the connection loss does not increase due to the remaining parts, and the set of temporary optical lines and equipment necessary for switching can be repeatedly used. Since the connection space of is limited to the connector connection, it is possible to avoid requiring a large space.

Therefore, according to the method of the present invention, it is possible to perform the non-instantaneous switching of the optical line with a slight additional cost and without causing problems such as connection loss and connection space.

[Brief description of drawings]

FIGS. 1 to 6 are stepless switching process diagrams of the optical line in the method of the present invention, FIG. 1 is an explanatory diagram showing a main part of the working optical switching line, and FIG. An explanatory view of a state in which a beam splitter is inserted at a connection point and a rod lens is arranged, FIG. 3 is an explanatory view of a state in which a temporary optical line is connected to a predetermined section of the optical line, and FIG. 4 is switching from the optical line. FIG. 5 is an explanatory view showing a state in which a target section line portion is separated, FIG. 5 is an explanatory view showing a state in which a switching optical line is connected to a predetermined section of the optical line, and FIG. 6 is a state in which a temporary optical line is separated from the optical line. FIG. 7 is an explanatory view illustrating a variable delay device in the method of the present invention, and FIGS. 8 to 10 are non-interruption switching steps of the optical line in the proposed example of the prior art of the present invention. It is explanatory drawing shown according to the switching order. 20 …… Current optical line 20M …… Section line section to be switched 21a-21h, 41b, 41c …… Rod lens 22, 24,40 …… Variable optical attenuator 23M, 23N …… Beam splitter 25 …… Variable delay Device 26 …… Temporary optical line 27 …… Electric / optical converter 28 …… Pulse generator 29 …… Optical / electrical converter 30 …… Pulse monitor 42 …… Switching optical line

Claims (1)

[Claims] 1. In a working optical line in which a plurality of section line sections are optically connected between these adjacent terminals with a separation gap interposed, the section line section to be switched is a temporary optical line and is switched. A method for switching the optical lines in order, and at the time of switching the predetermined optical lines, a means for generating an optical pulse, a means for measuring the phase difference of the optical wavelengths, and a variable for compensating the phase difference. A delay device, a working wavelength transmission type optical filter, a working wavelength light non-transmission type optical filter, a variable optical attenuator capable of desorption of these optical filters, a method using a beam splitter, and, It is a method in which a variable delay device and a variable optical attenuator are provided in the temporary optical line, and a variable optical attenuator is also provided in the switching optical line. Na Between the light incidence terminal of the section line portion and the light emission terminal of the section line portion adjacent thereto, and between the light emission terminal of the section line portion to be switched and the light incidence terminal of the section line portion adjacent thereto Insert a beam splitter between them, connect the temporary optical line where the working wavelength optical opaque optical filter is inserted in the variable optical attenuator to these beam splitters, and connect the optical pulse generating means to one of the beam splitters, After connecting the phase difference measuring means to the other beam splitter respectively, transmit the optical signals of different wavelengths to the working wavelength light from the optical pulse generating means to the switching target section line section and the temporary optical line, and Section, the optical signal of the different wavelength transmitted through the temporary optical line is measured by the phase difference measuring means, and the phase difference is compensated by the variable delay device attached to the temporary optical line, and then, The working wavelength optical opaque type optical filter inserted in the variable optical attenuator of the working optical line is replaced with the working wavelength optical transmitting type optical filter, and the working wavelength optical signal is also transmitted to the temporary optical line. As the next switching step in the above method, the section line section to be switched is removed from the working optical line from between the beam splitters, and the working wavelength optical opaque optical filter is inserted in the variable optical attenuator. After connecting the switching optical line to the location where the section line section to be switched is removed, transmit an optical signal of a different wavelength to the working wavelength light from the optical pulse generator to the temporary optical line and the switching optical line. Along with
The optical signals of the different wavelengths transmitted through the temporary optical line and the switching optical line are measured by the phase difference measuring means, and the phase difference is compensated by the variable delay device attached to the temporary optical line, and then the switching is performed. Replace the working wavelength optical non-transmissive type optical filter inserted in the variable optical attenuator of the working optical line with the working wavelength optical transmitting type optical filter and transmit the working wavelength optical signal to the switching optical line. That is, as the subsequent switching step in the above method, a temporary optical line, a beam splitter, an optical pulse generating means,
A method for switching the optical line without interruption, wherein the phase difference measuring means is removed from the working optical line.