JPH0865267A - Optical wdm information distributing network - Google Patents

Abstract

PURPOSE: To provide the optical WDM information distributing network with which the fluctuation or the like of communication demand can be flexibly dealt with. CONSTITUTION: Optical signals outputted from plural optical transmitters 1 are synthesized at a star coupler 5 and distributed out to the reception side. A multichannel wavelength selecting means 93 selects the plural signal beams of a prescribed wavelength out of the distributed out wavelength multiplexed beams, and the selected signal beams are simultaneously amplified by an optical amplifying means 94. This amplified output is distributed to plural outputs by an optical distributing means 95, outputted and supplied to an optical WDM receiver. At each optical WDM receiver, only the signal beam of the wavelength of a receiving object is passed through a tunable optical filter 98 and demodulated to an electric signal at an optical receiver 99.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a star type optical WDM in which signal light is wavelength division multiplexed / plurality distributed by a star coupler.
It relates to an information distribution network.

[0002]

2. Description of the Related Art Wavelength division multiplexing (WDM)
FIG. 9 shows the configuration of an optical WDM information distribution network using the ision multiplexing technology. In this figure, 1 ₁ , 1 ₂ ...
Reference numeral 1 _n denotes N optical transmitters to which optical signals of wavelengths λ _{1 to} λ _n are assigned. Also, 4 ₁ , 4 ₂ ... 4
_n and 6 ₁ , 6 ₂ ... 6 _n is an optical fiber, 5 is N multiplexed /
It is an N × N star coupler with N branches. In addition, 9 ₁ , 9 ₂
.. 9 _n is an optical WDM receiver, which includes a tunable optical filter 98 and an optical receiver 99, respectively.

Each of the optical transmitters 1 ₁ to 1 _n modulates an optical signal of an assigned wavelength with arbitrary information, and the modulated light is respectively transmitted to the star coupler 5 via the optical fibers 4 ₁ to 4 _n. Output. The star coupler 5 multiplexes these optical signals and equally outputs the results to the optical WDM receivers 9 _{1 to} 9 _n via the optical fibers 6 _{1 to} 6 _n . That is, the N-wave multiplexed signal lights of wavelengths λ _{1 to} λ _n propagate in the optical fibers 6 _{1 to} 6 _n , respectively.

The wavelength-multiplexed signal light incident on the optical WDM receivers 9 _{1 to} 9 _n via the optical fibers 6 _{1 to} 6 _n includes only one wave required for each of the tunable optical filters 98 _{1 to} 98 _n. The selected information is demodulated by the optical receivers 99 _{1 to} 99 _{n to} be communicated. For example, the optical WDM receiver 9 ₁ selects only the signal light of wavelength λ ₁ and demodulates it. Here, the wavelength of the signal light to be selected can be changed by adjusting the tunable optical filters 98 _{1 to} 98 _n.
Each of the receivers 9 _{1 to} 9 _n can demodulate any one piece of information among the N pieces of information.

Next, when the conventional optical WDM information distribution network described above is applied to the transmission of a wideband video signal (2.4 Gb / s) in a television station (Shimizu et al.
"Basic characteristics of M optical network" (refer to 1994 IEICE Spring Conference B1044).

FIG. 10 is a diagram showing a configuration example of the applied optical WDM information distribution network. In this figure, 1A,
1X and 1W are studios, and 9A, 9Y and 9Z are editing rooms. Here, six optical transmitters 1 ₁ to 1 ₆ are provided in the studio 1A.
And six TV cameras (not shown) connected to them, respectively, and the optical transmitters 1 ₁ to ₁₆ modulate the transmission light with the video signals of the corresponding TV cameras. Similarly, two optical transmitters 1 _i and 1 _j are provided in the studio 1X, and are connected to two TV cameras, respectively.
In addition, one optical transmitter 1 _n is provided in the studio 1W, and one TV camera is connected thereto.

On the other hand, in the editing room 9A, 6 optical WDM receivers 9 ₁ , 9 ₂ ... 9 ₆ and 6 TV monitors (not shown) respectively connected to them are provided. Cage, optical WDM
The receivers 9 _{1 to} 9 ₆ select and demodulate the video signal supplied from the received light to the corresponding monitor. Similarly, editing room 9Y the ten optical WDM receiver _{9 a ', 9 b' ···} 9 j ' is deployed at the same time utilize ten TV monitor. Further, one optical WDM receiver 9z is provided in the editing room 9Z and one TV monitor is used.

[0008]

By the way, between the studios 1A, 1X, 1W ... In FIG. 10 and the star coupler 5, as many optical fibers as the number of TV cameras used at the same time are installed. There is a need. Similarly, between the star coupler 5 and each of the editing rooms 9A, 9Y, 9Z, ..., It is necessary to install as many optical fibers as the number of TV monitors used at the same time. That is, when deploying a conventional optical WDM information distribution network in a television station, optical fibers must be installed in advance according to the number of TV cameras and TV monitors required in the studio and the editing room. I won't.

[0009] In this, for example studio 1A, by connecting the optical fiber 4 ₇ an optical receiver and additional other one, you can utilize the TV camera at the same time up to seven, or more eight If it becomes necessary to simultaneously use the TV camera, the optical fiber has to be newly laid, and the construction cost is high.

In the star coupler 5, a distribution loss of at least 3 k [dB] is unavoidable in the case of 2 ^k distribution, and the optical power per wavelength after distribution becomes less than the receiving sensitivity of the optical WDM receiver 9. In this case, reception becomes impossible, so the number of distributions of the star coupler 5, that is, the total number of connectable optical fibers 4 or 6 is limited. Therefore, when the number of studios is large, the number of fibers that can be deployed in each studio is extremely limited. That is, the number of TV cameras that can be used simultaneously in one studio is extremely limited. Similarly, in the editing room, the number of monitors that can be used simultaneously is limited.

As described above, when the conventional optical WDM information distribution network (FIG. 9) is provided, the number of TV cameras used in each studio and the number of TV monitors used in each editing room are strictly predicted in advance and the optical fiber is used. And the like, and the number of layable parts is limited by the performance of the star coupler 5. Therefore, there is a drawback that it is extremely difficult to flexibly deal with the increase or decrease or the relocation of the TV camera or the TV monitor.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical WDM information distribution network that can flexibly cope with fluctuations in communication demand and the like in view of the above circumstances.

[0013]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a conventional optical WDM information distribution network in which an M star wave required for an output of an optical star coupler among N wave length multiplexed lights. A multi-channel wavelength selecting means for selecting and transmitting only the signal light of (2 ≦ M <N), an optical amplifying means for inputting the output of the multi-channel wavelength selecting means, and an output of the optical amplifying means. Its most main feature is that it has a light distributing means for distributing.

That is, the light W according to claim 1 of the present invention.
The DM information distribution network, in order to flexibly cope with the increase and decrease in the number of optical WDM receivers, receives a plurality of optical transmitters that output lights of different wavelengths and outputs the output lights of the plurality of optical transmitters. An optical star coupler, at least one multi-channel wavelength selecting means for selectively outputting signal lights of a plurality of predetermined wavelengths from the distributed output of the optical star coupler, and an optical amplifier for amplifying the selected output light of the multi-channel wavelength selecting means. Means and
Optical distribution means for distributing a plurality of amplified outputs of the optical amplification means, a plurality of tunable optical filters for selecting a predetermined wavelength from a plurality of distributed outputs of the optical distribution means, and outputs of the plurality of tunable optical filters. And a plurality of optical receivers for respectively demodulating signals from light.

An optical WDM according to claim 2 of the present invention.
In addition to the above, the information distribution network, in order to flexibly respond to the increase or decrease of the number of optical transmitters, provides a plurality of optical transmitters that output lights of different wavelengths and an arbitrary output light of the plurality of optical transmitters. At least one optical multiplexing means for multiplexing, an optical star coupler for receiving and distributing and outputting the output light of the optical multiplexing means, and at least one for selectively outputting signal light of a plurality of predetermined wavelengths from the distributed output of the optical star coupler. One multi-channel wavelength selecting means, an optical amplifying means for amplifying the selective output light of the multi-channel wavelength selecting means, an optical distributing means for distributing a plurality of amplified outputs of the optical amplifying means, and a plurality of distributing of the optical distributing means. A plurality of tunable optical filters for selecting a predetermined wavelength from the output and a plurality of optical receivers for respectively demodulating signals from the output lights of the plurality of tunable optical filters are provided.

An optical WDM according to claim 3 of the present invention.
In the information distribution network, the optical multiplexing means of the transmitter according to the second aspect has wavelength selectivity in order to prevent the interference ripple when the transmitter fails.

An optical WDM according to claim 4 of the present invention.
In order to more flexibly cope with the increase in the number of optical WDM receivers, the information distribution network newly includes a second optical distribution means between the optical star coupler and the multi-channel wavelength selection means of the invention of claims 1 to 3. Prepared for

Further, an optical WD according to claim 5 of the present invention.
The M information distribution network, in order to more flexibly cope with an increase in the number of optical transmitters and the number of optical WDM receivers, the information distribution network according to claim
In addition to providing a plurality of the optical star couplers of the invention, an optical switch for selecting the plurality of star couplers is newly provided.

[0019]

In the optical WDM information distribution network according to the first aspect of the present invention, the newly provided multi-channel wavelength selection means first selects only the light of the wavelength to be received from the wavelength multiplexed light. Then, the lights of the selected plural wavelengths are inputted to the optical amplifying means and are collectively amplified. After that, it is demodulated into an electric signal in each optical WDM receiver through the optical distribution means. Here, since only the optical signal of the truly required wavelength is selected by the multi-channel wavelength selection means and input to the optical amplification means, a large amplification gain can be obtained without saturating the output of the optical amplification means. In this way, it becomes possible to increase the number of distributions in the light distribution means as desired.

Further, in the optical WDM distribution network according to the second aspect of the present invention, in addition to the above, the output of a plurality of optical transmitters having different wavelengths is provided by at least one newly provided optical multiplexer having wavelength selectivity. Are combined and then transmitted to an optical star coupler. In this way, it is possible to flexibly deal with the increase or decrease or the relocation of the optical transmitter.

In the optical WDM information distribution network according to the third aspect of the present invention, by providing the optical multiplexing means of the transmitter with wavelength selectivity, the transmitter that outputs the wavelength out of allocation due to a failure or the like is different. It is possible to prevent the transmission of the transmitter from being disturbed.

Further, in the optical WDM information distribution network according to the fourth aspect of the present invention, by providing the optical distribution means before the multi-channel wavelength selection means, more optical WDM receivers can be installed.

In the optical WDM information distribution network according to the fourth aspect of the present invention, a plurality of optical star couplers are provided, and an optical switch is provided to switch and use the star couplers, whereby an optical transmitter or an optical WDM receiver is provided. It is possible to add more than the number of wavelength multiplexes.

[0024]

Embodiments of the present invention will now be described in detail with reference to the drawings. <Embodiment 1> FIG. 1 is a block diagram showing Embodiment 1 of an optical WDM information distribution network of the present invention. The optical WDM information distribution network in this figure is provided as a system for handling a wideband video signal (2.4 Gb / s) in a television station, as in the conventional example described with reference to FIG. The same reference numerals are given to the portions corresponding to, and the description thereof will be omitted.

In the editing room 9A of FIG. 1, numeral 93 is a multi-channel wavelength selecting means, which is constituted by combining, for example, an optical demultiplexer, an optical multiplexer and a plurality of optical switches (described later). Further, 94 is an optical fiber amplifier for amplifying the optical signal, and 95 is 1 × for distributing one optical signal to eight optical signals.
The signal light from the optical fiber 6 ₁ laid in the editing room 9A is an 8-tree coupler, and multi-channel wavelength selecting means 93 is used.
And the tree coupler 95 via the optical fiber amplifier 94.
Is supplied to. Further, in the editing room 9A, 6 units of the TV monitor (not shown) are provided corresponding to the optical WDM receiver 91 _to 93 _6, the tree coupler 95 to the optical WDM receiver 91 _to 93 ₆ 6 out of the 8 outputs are connected.

In the editing room 9Y, 92 is 1 × 2.
It is an optical coupler and splits the signal light from the optical fiber 6y laid in the editing room 9Y into two. Distribution light of the optical coupler 92, respectively multichannel wavelength selection means 93 _a, 9
1 × through 3 _b and the optical fiber amplifier 94 _a, 94 _b
It is supplied to the 8-tree couplers 95 _a and 95 _b . Then, eight division output of tree couplers 95 _a is eight optical WDM receiver 9a respectively ', 9b' are input to the · · · 9h ', 2 a respective light among the eight outputs of the tree coupler 95 _b It is input to the WDM receivers 9a "and 9b", respectively. Also, the above optical WDM receivers 9a'-9h ', 9
The outputs of a "and 9b" are supplied to ten TV monitors provided correspondingly.

On the other hand, the optical fiber 6z is laid up to the editing room 9Z in which one TV monitor is installed, and an optical WDM
It is connected to the receiver 9z.

FIG. 2 shows multi-channel wavelength selecting means 93, 9
3 shows an example of the configuration of _a, 93 _b. In this figure, 934 is an optical demultiplexer, 935 is an optical multiplexer, 938 _{1 to} 938 _n are optical fibers, and 939 _{1 to} 939 _n are optical switches, and these constituent elements operate as follows.

Wavelengths λ ₁ and λ ₂ input to the optical demultiplexer 934
The 32 wavelength-multiplexed signals of λ _n are demultiplexed for each wavelength, and the optical fibers 938 ₁ , 938 _2, ...
Propagate through 938 _n . Optical switches 939 _{1 to} 939 _n are provided in the middle of the optical fibers 938 _{1 to} 938 _n , respectively, and only the switches corresponding to the light of the wavelength to be selected are turned on. The signal light that has passed through the optical switch in the ON state is multiplexed again by the optical multiplexer 935 and output. That is, the signal light of the wavelength selected by the optical switches 939 _{1 to} 939 _n is output as the multiplexed signal light.

A method of realizing the functions of the optical demultiplexer 934 and the optical multiplexer 935 in FIG. 2 with one arrayed waveguide diffraction grating type optical multiplexer / demultiplexer has been proposed by Tachikawa et al. Japanese Patent Application No. 5-233874, Japanese Patent Application No. 4-260222
reference).

Next, the operation of the first embodiment of the present invention shown in FIG. 1 will be described. First, when an image taken in the studio 1A is monitored in the editing room 9A, that is, the output light from the optical transmitters 1 ₁ to ₁₆ is changed to _six optical WDM receivers 9 ₁
To 9 in the case of each demodulated is _6, the optical switch 939 _{1 to 931 6} multi-channel wavelength selection means 93 (see FIG. 2) O
Set to N state and turn off other optical switches 939 _{7 to} 931 _n
State.

As a result, the optical fiber 61 shown in FIG.
Of the 32 wavelength-multiplexed signal lights transmitted through the optical transmitters, only the optical signals of the _six wavelengths λ _{1 to} λ 6 output by the optical transmitters 1 ₁ to ₁₆ are selected / multiplexed to select multi-channel wavelengths. It is output from the means 93. This 6-wavelength multiplexed signal is collectively amplified by an optical fiber amplifier, and then the tree coupler 95.
And are guided to the optical WDM receivers 9 _{1 to} 9 ₆ . In the optical WDM receiver, a tunable optical filter in each receiver selects only one wave to be received from the six waves and demodulates it in the optical receiver in the receiver. Then, for example, the image captured by the TV camera connected to the optical transmitter 1 ₁ is reproduced on the monitor connected to the optical WDM receiver 9 ₁ .

Similarly, when it is desired to reproduce the images of the ten TV cameras connected to the optical transmitters 1a, 1b ... 1j on the ten TV monitors installed in the editing room 9Y, it is often necessary. The channel wavelength selecting means 93a selects / combines the optical signals of the eight wavelengths λ _a ′, λ _b ′, ... λ _h ′, and the multi-channel wavelength selecting means 93 _b selects the optical signals of the two wavelengths λ _a ′ and λ _b ′. Are selected / combined,
Each optical switch group 939 (FIG. 2) is set.

As a result, the wavelength-multiplexed signal light transmitted through the optical fiber 6y is split into two in the optical coupler 92, and the eight wavelengths λ _a ′ to λ _h ′ of the eight wavelengths in the multi-channel wavelength selecting means 93 _a . The optical signals are selected / combined. The eight-wavelength multiplexed signal is the optical fiber amplifier 94.
is 8 distributed in a tree coupler 95 _a in after being collectively amplified at _a, and, in each of the optical WDM receiver 9 _a '~9 _h', select only one wave to be received, performs demodulation. Similarly, in the multi-channel wavelength selecting means 93 _b , only the optical signals of the two wavelengths λ _a ″ and λ _b ″ are selected from the wavelength multiplexed signal which is the other output of the optical coupler 92, and the optical WDM receiver 9 is selected. _They are selected / demodulated in _a "and _9b ", respectively.

On the other hand, in the editing room 9Z, λn desired to be received by the tunable optical filter in the optical WDM receiver 9z.
Of the signal light is selected and demodulated by the optical receiver in the optical WDM receiver 9z, and then the image is reproduced on the TV monitor.

Next, the roles played by the multi-channel wavelength selecting means 93 and the optical fiber amplifier 94 in the studio 9A having a plurality of TV monitors will be described with reference to FIG.

FIG. 3 shows an optical WDM from the optical transmitter 1 _{1 of} FIG.
6 is a level diagram showing how the optical signal power of wavelength λ ₁ changes in the optical path to the receiver 9 ₁ . The signal light power, which was +3 dBm at the output of the optical transmitter 1 ₁ , receives a loss of 3 dB due to fiber propagation loss, fiber connection loss, etc. before reaching the star coupler 5.
Since the star coupler 5 is distributed in 32, it receives a total loss of 18 dB including a distribution loss of 15 dB and an excess loss of 3 dB. The excess loss is assumed to be the worst value in consideration of the influence of variations due to the ports of the star coupler 5. Then, while propagating from the star coupler 5 to the editing room 9A, a loss of 3 dB is incurred due to fiber propagation loss, fiber connection loss and the like. In this way, the optical signal of wavelength λ ₁ that reaches each editing room becomes -21 dBm with a total loss of 24 dB.

Here, the receiving sensitivity of the optical WDM receiver is -2.
If it is 3 dBm, it is the optical WDM like the editing room 9Z.
When connected to the receiver directly to the optical fiber ₆₁ is able to demodulate select the desired signal. But,
An optical fiber amplifier is indispensable in an editing room having a plurality of optical WDM receivers like the editing room 9A. This is because the power of .lambda.1 reaching each editing room is -21 dBm, and even if only two distributions are made, it becomes -24 dBm or less and cannot be received by the optical WDM receiver having a receiving sensitivity of -23 dBm.

In addition, a multi-channel wavelength selecting means is indispensable before the fiber amplifier 94 in order to prevent saturation of the optical fiber amplifier. This is because, for example, when the multi-channel wavelength selecting means 93 is not provided in the editing room 9A, 32 wavelength multiplexed signals are input to the optical fiber amplifier 94. Here, when the saturation output power of the optical fiber amplifier 94 is +5 dBm, the optical power per wave in the amplifier output can be expected to be only about -13 dBm at worst in consideration of the variation in the power for each wavelength. Therefore, if the output of this optical amplifier is divided into eight by the tree coupler 95, the worst case is about -25 dBm per wave in consideration of the loss variation between the ports of the tree coupler.
Thus, the optical WDM receiver having the receiving sensitivity of -23 dBm cannot receive the signal. This state is shown by a broken line in FIG.

However, as shown in FIG. 1, the multi-channel wavelength selecting means 93 is provided in front of the optical fiber amplifier 94, and only the wavelengths required for reception (maximum 8 waves) are selected from the 32 wavelength multiplexed signals. Then, by inputting to the optical fiber amplifier 94, it is improved as shown by the solid line in FIG. That is, when the saturated output power of the optical fiber amplifier 94 is +5 dBm, the optical power per wave at the output of the optical fiber amplifier can be expected to be about -7 dBm even if the variation in the power for each wavelength is taken into consideration. Therefore, even if this output is divided into eight by the tree coupler 95, about -19 dBm per wave can be secured. Thus, the reception sensitivity-
The optical WDM receiver of 23 dBm can be selectively received. If the number of distributions in the tree coupler 95 is increased to 16, for example, there is a possibility that optical power per wave may not be -23 dBm due to an increase in distribution loss and excess loss. In other words, T which can be added in Studio 9A
The number of V monitors is about eight.

Next, the role played by the optical coupler 92, which is the second light distributing means, in the studio 9Y in which more than eight TV monitors are installed will be described.

As described above, the multi-channel wavelength selecting means 9
3, the total number of optical WDM receivers 9 that can be added using the optical amplifier 94 and the tree coupler 95 is about eight. However, it is possible to add up to 16 units by previously dividing the optical coupler 92 into two and separately providing a multi-channel wavelength selecting means, an optical amplifier, and a tree coupler. Of course, if the optical coupler 92 is changed to a tree coupler having a larger distribution number, it is possible to add more than 16 units.

The loss due to the multi-channel wavelength selecting means 93 and the optical coupler 92 can be tolerated for the following reason.
When receiving without using an optical fiber amplifier like in the editing room 9Z, the receiving sensitivity of the optical WDM receiver 9z is limited by the circuit noise of the optical receiver and stays at about -23 dBm, for example. However, when the optical fiber amplifier is used as in the studio Y, the optical fiber amplifier functions as a preamplifier, so that the minimum light receiving sensitivity at the input of the optical fiber amplifier can be realized up to, for example, about -40 dBm.
Therefore, for example, even if the loss of the multi-channel wavelength selection means 93 in the editing room 9A is 7 dBm, the optical power per channel input to the optical fiber amplifier 94 is −.
It is 28 dBm, which is within the receivable range (see FIG. 3).

Next, it will be described that the optical WDM information distribution network shown in FIG. 1 can flexibly cope with demand fluctuations.

Consider, for example, a case where there are 10 editing rooms in a television station and 22 rooms that may be renovated into editing rooms. In this case, each of the 32 optical fibers 61 to 6n from the optical star coupler 5 may be laid in each of the 32 rooms.

An editing room which initially requires only one monitor may be provided with only one optical WDM receiver like the editing room 9Z in FIG. When a new monitor is added to this room to have 2 to 8 monitors, the multi-channel wavelength selecting means 93, like the editing room 9A,
The optical fiber amplifier 94 and the tree coupler 95 may be introduced. When the number of monitors is increased to 9 or more, the optical coupler 92 may be introduced like the editing room 9Y, and the multi-channel wavelength selecting means 93, the optical fiber amplifier 94, and the tree coupler 95 may be added.

On the other hand, in the conventional optical WDM information distribution network shown in FIG. 10, when the total number of rooms which may become the editing room and the editing room in the future is 32, each room has only one fiber. Cannot be deployed. Therefore, only one TV monitor can be used in each room. Moreover, even if fibers are deployed only in 10 editing rooms,
Since only 3 to 4 monitors can be assigned to each room, the number of monitors that can be used simultaneously in each room is limited to 3 to 4.

As described in detail above, according to the first embodiment shown in FIG. 1, even if the number of monitors changes due to demand fluctuations, it is possible to deal with it by simply adding devices in each editing room.
There is no need to redo the fiber installation work from the optical star coupler to each room.

In the first embodiment (see FIG. 1),
For convenience of explanation, the number of distributions of the star coupler 5 is 32 and the number of distributions of the tree couplers 95, 95a and 95b is 8, but the number of distributions is not limited to this, and the number of editing rooms and optical WDMs are not limited thereto.
Various values can be designed according to the receiving sensitivity of the receiver and the saturation output intensity of the optical fiber amplifier.

In the first embodiment (see FIG. 1), a multi-channel wavelength means composed of an optical multiplexer / demultiplexer and an optical switch is used (FIG. 2), but this is an optical component having a similar function. , For example, an acousto-optic filter may be used (Fukutoku et al., "Study of optical add / drop circuit using polarization-independent acousto-optic filter", IEICE 19
1993 Autumn Conference Lecture Collection B-906).

Further, although the optical fiber amplifier is used in FIG. 1, the present invention is not limited to this as long as it is possible to collectively amplify the wavelength multiplexed optical signal. For example, a semiconductor optical amplifier is used. Good.

<Embodiment 2> FIG. 4 is a block diagram showing another embodiment of the optical WDM information distribution network of the present invention. The optical WDM information communication distribution network in this figure is different from that of the first embodiment (FIG. 1) in that the output light from a plurality of optical transmitters in the same studio has an arrayed waveguide grating type optical multiplexer / demultiplexer having wavelength selectivity. The point is that the signals are input to the optical star coupler 5 after being multiplexed at 2 (described later). The operation of this embodiment is the same as that of the above-described first embodiment except the function of the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer.

In FIG. 4, reference numerals 2 and 2'indicate a 16 × 16 arrayed waveguide diffraction grating type optical multiplexer / demultiplexer provided in the studio. The configuration is shown in FIG. 5 and the multiplexing characteristic is shown in FIG. Sex.

In FIG. 5, reference numeral 23 denotes an input waveguide group, 2
4, 25 are slab waveguides, 26 array waveguide diffraction gratings,
27 is an output waveguide group. In general, the number of waveguides of the input waveguide group 23 and the output waveguide group 27 is arbitrary, but here, 16 waveguides are provided, and I1, I2, ...
..I16 and J1, J2 ...

The arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2 has the input waveguide I1 with the multiplexing characteristic shown in FIG.
To the output waveguide J9 selectively transmits the light of wavelength λ ₁₆ and selectively transmits the light of λ ₁₅ from I2 to J9,
.., selectively transmits the light of λ ₁ from I16 to J9.
Therefore, if the optical signals from the optical transmitters are connected to the input waveguides corresponding to the respective wavelengths and the optical fiber 41 is connected to the output waveguide J9, the signals from the respective optical transmitters 1 are combined. After that, it is sent toward the star coupler 5.

With such a configuration, in the studio in which the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2 is installed, a maximum of 16 optical transmitters 1 can be operated via one optical fiber 4. It becomes possible to transmit at the same time. For example, in the studio 1A of FIG. 4, the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2 is used.
Six optical transmitters 11 to 16 are connected to, and the remaining 1
The zero input waveguides 23 (see FIG. 5) are empty. Therefore, 10 more TV cameras can be added to this studio 1A.

Further, since the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2 has the wavelength selectivity shown in FIG. 6, for example,
If the optical transmitter 1 ₂ fails and its output light wavelength deviates to a wavelength different from the original λ ₂ (eg, λ ₁ ), the optical output is removed and output into the fiber 4 _1. There is no such thing. That is, it is possible to prevent the interference with the optical signal of the other optical transmitter 1 caused by the failure of the certain optical transmitter 1.

As described above, according to this embodiment,
It is possible to flexibly add a TV camera without additionally laying the optical fiber 4, and further, when the optical transmitter 1 fails, it is possible to suppress the spread of failures due to the failure.

It should be noted that in FIG.
Although the case where the 6 × 16 arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2 is used has been described, it is of course possible to use optical multiplexers / demultiplexers having different numbers of multiplexing. For example, if a 32 × 32 array waveguide diffraction grating type optical multiplexer / demultiplexer is used, it is possible to add up to 32 optical transmitters in each studio.

Further, an ordinary optical multiplexer may be used instead of the arrayed waveguide diffraction grating type optical multiplexers / demultiplexers 2 and 2 '.
However, in this case, the above-described effect of preventing the failure cannot be obtained.

<Third Embodiment> FIG. 7 shows an optical WD according to the present invention.
It is a block diagram which shows Example 3 of M information distribution network, The same code | symbol is attached to the part corresponding to FIG. 4, and the description is abbreviate | omitted.
This optical WDM information communication distribution network is different from that of the second embodiment (FIG. 4) in that it is provided with a plurality of optical star couplers 51 to 54, and optical switches 3A, 3X, 3 are provided in each studio and editing room.
The point is that W, 7A, 7Y, and 7Z are provided so that the optical star couplers 51 to 54 to be connected can be selected.

In FIG. 7, 3A and 3W are 1 × 4 optical switches, 3X is a 2 × 4 optical switch, 7A and 7Z are 4 × 1 optical switches, and 7Y is a 4 × 2 optical switch. The output of the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2 of the studio 1A is connected to the optical switch 3A, and the four outputs of the optical switch 3A are optical fibers 4 _{1, 1,} 4 _1, 2, 4 ₁ 3, 4 _{1, respectively.}
4 through the optical star coupler 51, 52, 53, 5 respectively
4 is connected. Similarly, the output of the optical transmitter 1 _n of the studio 1W is connected to the optical switch 3W,
The four outputs of W are connected to the optical star couplers 51 to 54 via the optical fibers 4 _n 1 to 4 _n 4, respectively.

Further, the studio 1X is provided with two arrayed waveguide diffraction grating type optical multiplexer / demultiplexers 2'1 and 2'2, and two optical transmitters are connected to each of them. Here, the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2′1, 2′2
Output is connected to a 2x4 optical switch 3X, then 2x
The four outputs of the four optical switch 3X are the optical fibers 4 _i 1 to 4 _i.
4 are connected to optical star couplers 51 to 54, respectively.

On the other hand, one output of each of the optical star couplers 51 to 54 is passed through the optical fibers 6 _{11 to} 6 ₁₄ and edited in the editing room 9A.
4 × 1 optical switch 7A, and one of them is guided to the multi-channel wavelength selecting means 93. Similarly, one output of each of the optical star couplers 51 to 54 is connected to the 4 × 1 optical switch 7Z of the editing room 9Z via the optical fibers 6z1 to 6z4, and any one of them is guided to the optical WDM receiver 9z.

The optical star coupler 5 is connected to the editing room 9Y.
One output of each of 1 to 54 is an optical fiber 6y1 to 6y
4 is connected to the 4 × 2 optical switch 7Y via 4 and the two outputs of the optical switch 7Y are respectively multi-channel wavelength selecting means 9
It is connected to 3 _a, 93 _b.

Next, the roles of the plurality of optical star couplers 51 to 54 and the optical switches 3A, 3X, 3W, 7A, 7Y and 7Z will be described.

The studio 1A of FIG. 7 is connected to the optical star coupler 51 by an optical switch 3A, for example. When the camera image in the studio 1A is edited in the editing room 9A, the optical fiber 6 ₁₁ may be selected by the optical switch 7A. That is, the optical WD including the optical star coupler 51 and functioning in the same manner as in the second embodiment (FIG. 4) described above.
An M information distribution network can be constructed.

In the studio 1X, the optical transmitter 1
The optical signals of wavelengths λ ₉ and λ _{1 0} output from _i 1,1 _j 1 are combined by the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2′1 and guided to, for example, the optical star coupler 51 by the optical switch 3X. Get burned. On the other hand, the wavelength λ output from the optical transmitters 1 _i 2 and 1 _j 2
The optical signals of ₉ and λ ₁₀ are combined by the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2′2 and guided to, for example, the optical star coupler 52 by the optical switch 3X.

Here, in the editing room 9Y, for example,
The 4 × 2 optical switch 7Y may connect the optical star coupler 51 and the multi-channel wavelength selecting means 93a, and the optical star coupler 52 and the multi-channel wavelength selecting means 93b, respectively. In this case, the optical transmitter of the studio 1A is connected to the optical WDM receiver 9 of the editing room 9A, and two of the studios 1X are sent.
The optical transmitters 1 _i 1, 1 _j 1 can be connected to the eight optical WDM receivers 9 _a ′ to 9 _h ′ in the editing room 9 Y via the optical star couplers 51, respectively, and the above-described embodiment can be used. 2 (FIG. 4), an optical WDM information distribution network equivalent to that of FIG. on the other hand,
The remaining optical transmitters 1 _i 2, 1 _j 2 of the studio 1X,
Two optical WDM receiver 9 _a of the editing room 9Y ", 9 _b"
Can be connected via the optical star coupler 52, and an optical WDM information distribution network similar to that of the second embodiment can be constructed.

Similarly, in the studio 1W and the editing room 9Z, any one of the optical star couplers 51 to 54 used together by the optical switches 3W and 7Z may be selected.

When only one star coupler 5 is used as in the above-described embodiment (FIGS. 1 and 4), the number of signals that can be transmitted by the star coupler 5 (wavelength multiplex number) causes the entire network. While the number of signals that can be transmitted is limited,
According to the third embodiment, by using different optical star couplers 51 to 54 for each studio, or by using a plurality of optical star couplers 51 to 54 in the same studio, the number of wavelengths exceeding the wavelength multiplexing number can be increased. The optical transmitter 1 can be used at the same time. That is, if the wavelength multiplexing number is W and the number of optical star couplers is S, it is possible to use a maximum of W × S optical transmitters at the same time.

Thus, this embodiment is the same as the first and second embodiments.
In addition to the effect described in the above, there is an effect that the number of optical transmitters 1 exceeding the number of wavelength division multiplexes can be added, and the network can be expanded more flexibly.

In this embodiment (see FIG. 7), the optical transmitters 1 _i 1,1 _j 1,1 _i 2,1 _j 2 are connected to the same studio 1.
Although it is deployed in X, it is of course possible to deploy this in a separate studio. That is, the optical transmitters 1 _i 1,1 _j 1 and the arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2′1 are arranged in the studio 1X, while the optical transmitters 1 _i 2,1 _j 2 and the arrayed waveguide are arranged. The diffraction grating type optical multiplexer / demultiplexer 2'2 may be arranged in another studio 1X '(not shown), and the optical switch 3X may be arranged in either studio or in the middle thereof. In this case, there is an advantage that the number of studios can be increased without being limited by the number of distributions in the optical star coupler.

[0074] Similarly, in FIG. 7, includes an optical WDM receiver 9 _a 'to 9 _h', etc. The editing room 9Y, optical WDM receiver 9
_a ", 9 _b" and the like may be provided in a separate editing room 9Y '(not shown). In this case, there is an advantage that the number of editing rooms can be increased without being limited by the number of distributed optical star couplers.

Further, in FIG. 7, the number of star couplers is 4, but this can be freely increased or decreased. Further, in FIG. 7, the studio and the editing room are configured so that they can be connected to all the optical star couplers by optical switches, but if necessary, they may be configured to connect to only some of the optical star couplers. But of course

Further, in the above description using FIG. 7, it was explained that a so-called spatial optical switch is used, in which all wavelength-multiplexed light input to the optical switch is output to any one output as it is. Alternatively, a wavelength selective optical switch may be used instead. Here, the wavelength selective optical switch is an optical switch capable of performing a path switching function by the optical switch separately for each wavelength, and is configured as shown in FIG. 8, for example.

In FIG. 8A, the 2 × 2 wavelength selective switch has two input ends, two corresponding output ends, and a switching input. For example, one input end has λ ₁ , λ. ₂
... The wavelength-multiplexed light of λn has λ ' ₁ , at the other input end,
λ _'2, ..., λ' wavelength-multiplexed light of _n is to each inputted. Here, the switching input of a wavelength lambda _h and the wavelength lambda _k (h,
k) is performed, only the optical signals of the wavelengths λ _h and λ ′ _h and the wavelengths λ _k and λ ′ _k are interchanged and output,
Light of other wavelengths is output from the corresponding output end as it is. That is, it is possible to switch, for each wavelength, whether the two outputs are transmitted through or through.

The 2 × 2 wavelength selective switch having such a function has two demultiplexers 9 as shown in FIG. 8B, for example.
34, n 2 × 2 optical switches 35, and two multiplexers 935. That is, the input wavelength-multiplexed light is demultiplexed by the demultiplexer 934 for each wavelength and input to the n 2 × 2 optical switches. The outputs of the n 2 × 2 optical switches are combined by the combiner 935 and output again as wavelength-multiplexed light. In this way, the function shown in FIG. 8A is realized by switching the 2 × 2 optical switch corresponding to each wavelength to the through or cross state.

Then, for example, in FIG. 7, by using a 2 × 4 wavelength selective optical switch instead of the 2 × 4 optical switch 3X, the outputs of the optical transmitter 1 _i 1 and the optical transmitter 1 _j 2 are made the same. It is also possible to lead to the optical star coupler and simultaneously monitor in the studio 9A. That is, more flexible connection can be realized by using the above-mentioned wavelength selective optical switch instead of the simple spatial optical switch.

[0080]

As described in detail above, the first aspect of the present invention
According to the optical WDM information distribution network of No. 2, the multi-channel wavelength selecting unit newly provided in each receiving side terminal node selects only a plurality of lights having the wavelengths truly required, and then the optical amplifying unit collectively amplifies the plurality of lights. It is possible to arbitrarily increase the number of reception channels without changing the connection with the star coupler by configuring the optical WDM receivers to be distributed and received respectively. Therefore, it is possible to flexibly add an optical receiver.

According to the optical WDM information distribution network of the second aspect, in addition to the above-mentioned effect, the transmitting side terminal is provided with the optical multiplexing means having wavelength selectivity in each transmitting side terminal node. The number of transmitters at the node can be increased arbitrarily without changing the connection with the star coupler, and it becomes possible to flexibly deal with equipment renewal.

Further, according to the optical WDM information distribution network of the third aspect, there is also an effect that it is possible to prevent the propagation of a failure at the time of a transmitter failure by the multiplexing means having wavelength selectivity.

According to the optical WDM information distribution network of the fourth aspect, in addition to the above-mentioned effect, it becomes possible to further increase the number of distributions by the second optical distribution means.

Further, according to the optical WDM information distribution network of the fifth aspect, in addition to the above effects, a plurality of optical star couplers are provided so that the star coupler to be used by the optical switch can be selected. , It becomes possible to use a plurality of optical transmitters of the same wavelength at the same time, and it becomes possible to add the number of transmitters and receivers exceeding the wavelength multiplexing number.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an optical WDM information distribution network according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the configuration principle of the multi-channel wavelength selection means 93 of FIG.

FIG. 3 shows an optical transmitter 1a to an optical WDM receiver 9a in FIG.
It is a figure which shows the change of the optical power of the signal sent to.

FIG. 4 is a configuration diagram showing an optical WDM information distribution network according to a second embodiment of the present invention.

5 is an arrayed waveguide diffraction grating type optical multiplexer / demultiplexer 2 of FIG.
3 is a diagram for explaining the configuration of FIG.

FIG. 6 is a diagram for explaining a multiplexing characteristic of the optical multiplexer / demultiplexer 2.

FIG. 7 is a configuration diagram showing an optical WDM information distribution network according to a third embodiment of the present invention.

FIG. 8 is a diagram for explaining a function (FIG. 8A) and a configuration example (FIG. 8B) of the wavelength selective optical switch.

FIG. 9 is a configuration diagram showing a conventional optical WDM information distribution network.

FIG. 10 is a diagram for explaining a deployment example of a conventional optical WDM information distribution network.

[Explanation of symbols]

1A, 1X, 1W Studio 1 ₁ to 1 _n Optical transmitter 2, 2'Array waveguide Diffraction grating type optical multiplexer / demultiplexer 3A, 3X, 3W, 7A, 7Y, 7Z Optical switch 4 ₁ to 4 _n Optical fiber 5 Optical Star coupler 6 _{1 to} 6 _z optical fiber 9 A, 9 Y, 9 _Z editing room 9 _{1 to} 9 _z optical WDM receiver 92 optical coupler 93, 93 _a , 93 _b multi-channel wavelength selecting means 94, 94 _a , 94 _b optical fiber amplifier 95,95 _a, 95 _b light tree coupler

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H04B 10/20 H04B 9/00 N (72) Inventor Kiyoshi Nosu 1-1-1, Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nippon Telegraph and Telephone Corporation

Claims (5)

[Claims] 1. A plurality of optical transmitters that respectively output lights having different wavelengths, an optical star coupler that inputs and outputs the output light of the plurality of optical transmitters, and a predetermined output from the distributed output of the optical star coupler. At least one multi-channel wavelength selecting means for selectively outputting signal light of a plurality of wavelengths, an optical amplifying means for amplifying selected output light of the multi-channel wavelength selecting means, and an optical distribution for distributing a plurality of amplified outputs of the optical amplifying means Means, a plurality of tunable optical filters for selecting a predetermined wavelength from a plurality of distributed outputs of the optical distributing means, and a plurality of optical receivers for respectively demodulating signals from output lights of the plurality of tunable optical filters. An optical WDM information distribution network comprising: 2. A plurality of optical transmitters that respectively output lights having different wavelengths, at least one optical combining unit that combines arbitrary output lights of the plurality of optical transmitters, and an output light of the optical combining unit. An optical star coupler for inputting and distributing output, at least one multi-channel wavelength selecting means for selectively outputting signal light of a predetermined plurality of wavelengths from the distributed output of the optical star coupler, and a selected output light of the multi-channel wavelength selecting means A light amplifying means for amplifying the light, a light distributing means for distributing a plurality of amplified outputs of the light amplifying means, a plurality of tunable optical filters for selecting a predetermined wavelength from a plurality of distributed outputs of the light distributing means, An optical WDM information distribution network comprising: a plurality of optical receivers for respectively demodulating signals from output lights of a plurality of tunable optical filters. 3. The optical WDM information distribution network according to claim 2, wherein the optical multiplexing means has wavelength selectivity. 4. The optical WDM information distribution network according to claim 1, further comprising a second optical distribution unit between the optical star coupler and the multi-channel wavelength selection unit. 5. A plurality of said optical star couplers are provided, said optical transmitter or said optical multiplexing means and said plurality of optical star couplers are connected via an optical switch, and said plurality of optical star couplers and at least one of said optical star couplers. The optical WDM according to any one of claims 1 to 4, wherein the multi-channel wavelength selecting means is connected through an optical switch.
Information distribution network.