JP2001168844A - Optical time division multiplex module and optical time division multiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical time division multiplex module that can extract desired even number multiplex signal, without causing conventional noise problems. SOLUTION: This optical time division multiplex module 10 is provided with an input port 12, a plurality of output ports 16a, 16b, a branching means 13 that divides an optical carrier received by the input port 12, a couple of modulation means 14, 15 that modulate respective branched carriers obtained by the branch means with respective modulation signals, delay means 18a, 18b that give a mutual phase difference to a modulated light, a composting means 17 that combines both the modulated lights to which the phase difference is given, and a division means 17 that divides the multiplex signal light obtained through the compositing forward the two output ports 16a, 16b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical signal multiplexing module suitable for use in an optical time division multiplex transmission system (OTDM) of optical communication and an optical multiplexing apparatus using the module.

[0002]

2. Description of the Related Art In an optical time division multiplex transmission system of optical communication, for example, an optical carrier pulse of 10 GHz is divided into two systems,
The optical carrier pulse of each system is modulated by a data signal of, for example, 10 Gbit / sec. After one of the two modulated carrier pulse lights is given a phase difference of a half cycle (π) compared to the other, the two modulated carrier pulses are combined. By this interleaving processing, for example, 10 GHz
Is transmitted as an optical signal of 20 Gbit / sec.

For the multiplexing of the optical signal, a duplex module having a single input port and a single output port is used. Based on this duplex module, by combining a plurality of duplex modules, it is possible to realize a multiplexer capable of obtaining a desired even-multiplex (two-, four-...) Multiplex signal. it can. For example, in a four-multiplexer, after one output light (two-multiplex) of a pair of duplex modules passes through a time delay element,
The light is combined with the output light (two multiplexes) of the other multiplexing module.
Four multiplexed light, that is, four multiplexed light is output.

[0004]

By the way, in a multiplexing apparatus in which conventional duplex modules are combined, the optical output of each duplex module is output from a single output port as light combined by combining means. Is output. Therefore, for example, when a four-multiplexer is used to obtain a two-multiplex signal from this, in order to extract a stable double signal in response to the modulation signal of one of the double modules from the above-described combining means. It is necessary to keep inputting a "0" signal to the other duplex module as a modulation signal of the other duplex module. Moreover, in this case, the noise component passing through the other duplexing module is superimposed on the two multiplexed signals extracted from the combining means via the single output port. It has been strongly desired to reduce the amount.

An object of the present invention is to provide an optical time division multiplexing module capable of extracting a desired even-multiplexed signal without causing a noise problem as in the prior art, and an optical time division multiplexing module using this optical time division multiplexing module. It is to provide a division multiplexing device.

[0006]

SUMMARY OF THE INVENTION The basic concept of the present invention is to provide an optical time division multiplexing module with at least two output ports.

In order to realize this basic concept, an optical time division multiplexing module according to the present invention comprises an input port and a plurality of output ports, a branching means for splitting an optical carrier input to the input port, A pair of modulating means for modulating each of the branch carriers obtained by the branching means with a respective modulating signal; a delay means for giving a mutual phase difference to the modulated modulated light; And a splitting means for splitting the multiplexed signal light obtained by the synthesis toward at least two of the output ports. I do.

In the module according to the present invention, the two-multiplexed signal light combined by the combining means is distributed to at least two output ports by the dividing means.
Accordingly, it is possible to use the multiplexed signal light from one output port for the subsequent multiplexing processing as necessary, and to use the two multiplexed light from the other output port as necessary. it can.

Even if another optical signal is combined with the two-multiplexed signal light from the one output port via, for example, combining means, the influence is exerted on the two-multiplexed light from the other output port. However, it is possible to extract a good two-multiplex signal with little noise from the other output port.

The synthesizing means and the dividing means can be constituted by half mirrors which also have the functions of the two means.
The modules can be used in pairs. In this case, the arrangement of the input ports and the output ports of the pair of modules is made to be line-symmetrical between the pair of modules. Above, desirable. The modulation means may be a reflection type modulation means whose input port also serves as its output port. As the reflection type modulation means, a reflection type, for example, an electroabsorption type optical modulator can be used. In the case where a reflection type modulation unit is used, the branching unit, the synthesizing unit, and the dividing unit can be configured by a half mirror that also functions as each of these units.

An optical time-division multiplexing device according to the present invention using the module includes: at least one pair of the modules; a second branching unit for guiding an optical carrier to each of the input ports of the module; Second delay means for providing a mutual phase difference to the multiplexed light output from one of the output ports of each of the two modules, and second combining means for combining the multiplexed light provided with the phase difference And characterized in that:

According to the optical time-division multiplexing device of the present invention, for example, four multiplexed lights obtained by combining two multiplexed lights from the one output port of both the modules are derived from the second combining means. In parallel with this, two multiplexed lights can be derived from the other output port of each module.

The multiplexed light from the other output port of each module is not affected by the output light from the other module that forms a pair with each other. Are not superimposed.

By providing switching means for selectively taking out the multiplexed light from the other output port of one of the modules and the multiplexed light from the second combining means, for example, two- and four-multiplexed optical signals are provided. Can be selectively taken out.

The switching means includes a coupler for receiving the multiplexed light from the other output port of the one optical module via the transmission path having the same distance from the other output port and the second combining means, and the coupler. And an optical attenuator inserted into each of the two transmission paths to select the multiplexed light output from the optical path.

The module, the second branching means, and the second synthesizing means are arranged on a unit board which can be inserted and inserted in a rack in a rack. By inserting the multiplexed light into the rack, desired even-number multiplexed light can be obtained relatively easily.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. <Example 1> FIG. 1 shows Example 1 of an optical time division multiplexing module 10 (10A and 10B) according to the present invention.
In the example shown in FIG. 1, a pair of optical time-division multiplexing modules 1
0A and 10B are shown.

Each optical time division multiplexing module 10 (10A
And 10B) are a support plate 11, a first half mirror 13 disposed on the support plate for dividing incident light from the input port 12 into two systems, and a first half mirror 13 from one of the half mirrors. First light modulating means 14 for modulating the split light, that is, the light of the first split path, and modulating the other split light, that is, the light of the second split path, from the first split means; Modulating means 15 and a second half mirror 17 for synthesizing the modulated light from both modulating means 14 and 15 and guiding the synthesized multiplexed light to two output ports 16a and 16b. Prepare. The two light modulating means 14 and 15 are arranged in parallel with each other in the example shown in FIG.

Since each of the modules 10A and 10B is the same except for the arrangement of the modulated signal and the components, which will be described later, one of the modules (10A or 10B) will be described for the sake of simplicity. .

Each of the input ports 12 of the optical time division multiplexing module 10 (10A or 10B)
An optical carrier with a basic repetition frequency of 0 Gbit / s (10 Gbps), ie a clock frequency of 10 GHz, is guided. This optical carrier is split into two systems by the first half mirror 13, and one of the carriers is
The light is guided to the input port 14 a of the first light modulation unit 14. The other carrier obtained by splitting by the first half mirror 13 as a branching unit passes through a first prism 18a as a reflecting unit, and then passes through a second modulator 1
5 to the input port 15a.

Each of the optical modulators 14 and 15 receiving the branched carrier waves outputs an electric signal of, for example, an NRZ (non-return-to-zero) type 10 Gbps equal to the clock frequency to a signal input terminal 14b.
And 15b, the respective input ports 14a
And 15a are modulated by the respective input signals (NRZ), and the modulated light (RZ: return to zero) is emitted from the respective output ports 14c and 15c. In the example shown in FIG. 1, the input ports 14a and 15a and the output port 14 are used as the first and second light modulating units 14 and 15, respectively.
A so-called transmissive electroabsorption optical modulator (EA modulator) is used in which c and 15c are linearly arranged at both ends of the modulator body. As a modulation method, for example, ASK modulation is used.

The modulated light output from the output port 14c of the first light modulating means 14 composed of the transmission type electro-absorption type light modulator is directed to the second half mirror 17.
Further, the modulated light output from the output port 15c of the second optical modulation means 15 composed of a transmission type electro-absorption type optical modulator passes through the second prism 18b which is a reflection means, thereby forming the first modulated light. The second half mirror 1 passes through a path orthogonal to the light to be modulated from the output port 14 c of the light modulation unit 14.
Pointed at 7.

The second half mirror 17 is arranged at the intersection of the orthogonal paths of the modulated light, and
One half of the modulated light from the fourth output port 14c is reflected light, and guided to one output port 16a provided in a posture and position orthogonal to the output port 14c.
Further, the second half mirror 17 is connected to the first light modulating unit 1.
The other half of the modulated light from the fourth output port 14c is guided as transmitted light to the other output port 16b provided at the matching position of the output port 14c.

Further, the second half mirror 17 is
From the output port 15a of the light modulation means 15 to the prism 18
b, and guides one half of the modulated light as transmitted light to the one output port 16a.
The other half of the modulated light from the second modulating means 15 that has passed through is guided as reflected light to the other output port 16b.

Therefore, each optical time division multiplexing module 10
(10A and 10B), the second half mirror 17
As a result, the modulated lights from the respective light modulating units 14 and 15 are combined with each other, and the combined modulated lights are divided into output ports 16a and 16b, respectively. From this, the second half mirror 17 functions as a combining unit that combines the modulated waves from both the light modulating units 14 and 15, and also combines the modulated waves from the two light modulating units 14 and 15 into both. It functions as dividing means for dividing the output ports 16a and 16b.

Each optical time division multiplexing module 10
In (10A and 10B), the first and second prisms 18a and 18b inserted into the other branch path reach the second half mirror 17 from the first half mirror 13 via the first light modulating means 14 to the second half mirror 17. Branch path, first half mirror 13 to prism 18a, second light modulating means 1
5 and the second half mirror 17 through the prism 18b.
Between the second branch path and the second branch path, the optical signal passing through both paths has a path difference that generates an odd multiple of a half cycle (π) of the reference clock cycle.

Therefore, both prisms 18a and 18b
Substantially functions as delay means for giving a phase difference to the light passing through both branch paths. For example, 10 G synthesized by the second half mirror 17 due to the shift of the phase difference.
The 2 bps modulated light is interleaved with each other to form an RZ 20 Gbps multiplexed signal light, that is, a 2 multiplexed signal light (2RZ).
And 16b.

Output signals (2RZ) from both output ports 16a and 16b do not interfere with each other,
Are separated from each other. Of the multiplexed light (2RZ) from these two output ports 16a and 16b, for example, the multiplexed signal light (2RZ) from one output port 16a is used as a signal for further multiplexing, and in parallel with the other, Multiplexed signal light (2R
Z) can be effectively used as it is as the two-multiplex signal light.

The two multiplexed signals are further multiplexed,
Thus, in order to obtain even multiplex signals (four multiplex signals, six multiplex signals, eight multiplex signals...) Such as four multiplex signals, a pair of optical time division multiplex modules 10 (10
A and 10B) are preferably used.

For example, mutually different modulated signals (NRZ)
The two multiplexed signals from one optical time-division multiplexing module 10A input to the respective signal input terminals 14b and 15b of both optical modulation means 14 and 15, and another modulated signal (NRZ) different from each other 2 from the other optical time-division multiplexing module 10B input to the signal input terminals 14b and 15b of the modulating means 14 and 15, respectively.
To obtain a 4-multiplex signal by multiplexing with a multiplex signal, it is necessary to further combine both 2-multiplex output signals as described later.

For this combination, as shown in FIG. 1, both optical time division multiplexing modules 10 (10A and 10B)
Components (12, 13, 14, 15, 16a, 16)
b, 17, 18a and 18b) are represented by imaginary lines 19
Is desirably line-symmetric. This symmetrical arrangement allows the two output ports 16a to face each other, so that no special direction means for changing the direction in order to combine the multiplexed lights from the two output ports 16a is required. For this reason, it is advantageous to arrange the pair of optical time-division multiplexing modules 10 (10A and 10B) in a line-symmetrical arrangement as described above, from the viewpoint of simplifying the configuration and downsizing the device.

<Example 2> FIG. 2 shows an optical time division multiplexing apparatus 20 using a pair of optical time division multiplexing modules 10A and 10B shown in FIG. The optical time-division multiplexing device 20 guides a carrier wave to a substrate 21, a pair of optical time-division multiplexing modules 10A and 10B disposed on the substrate, and the input port 12 of each of the modules 10A and 10B. A second delay means 23 for giving a phase difference between the two multiplexed lights output from the one output port 16a of each of the modules 10A and 10B, and a double multiplexing means. A second synthesizing unit for synthesizing light. As the second delay means 23 for delaying the optical signal, a conventionally well-known optical delay element including an optical element such as lithium niobate can be appropriately used.

The optical time-division multiplexing device 20 has, for example, a 10 Gbps (10 Gbps)
(Hz), the carrier is guided to the second branching means 22 through the input port 25. The second branching unit 22 can be constituted by, for example, a half mirror arranged at an angle in the incident light path. The second branching means 22 composed of a half mirror guides one half of the carrier wave from the input port 25 to the input port 12 of one of the optical time division multiplexing modules 10A as transmitted light. Further, the second branching means 22 includes an input port 25.
The other half of the carrier wave from is transmitted as reflected light to the input port 12 of the other optical time division multiplexing module 10B.

The 10 Gbps transmission carrier guided to one optical time-division multiplexing module 10A is converted into, for example, a 20 Gbps two-multiplex signal as described in the first embodiment by using both output ports 16a of the multiplexing module 10A. And 16b. The two multiplexed signal of 20 Gbps from one output port 16a is guided to the first spare output port 26a of the optical time division multiplexing device 20, so that the two modulating means 14a of the multiplexing module 10A.
And 15 (see FIG. 1), for example, 20 Gbps 2
Multiplexed signals can be derived from the first spare output port 26a. On the other hand, the two multiplexed signal of 20 Gbps from the other output port 16b of the multiplexing module 10A is provided with a second delay means 23 which gives the signal a phase delay of an odd multiple of a quarter period (π / 2). Through the second synthesizing means 24
Will be guided to.

The other optical time division multiplexing module 1
0B, the reflected light from the second branching means 22 is, as in the module 10A, 20 Gb.
The multiplexing module 10B
Are output from both output ports 16a and 16b. The two multiplexed signal from one output port 16a is guided to the second spare output port 26b of the optical time division multiplexing device 20, so that the two multiplexed signals of
A multiplexed signal according to a and 15b can be derived from the second spare output port 26b. On the other hand, the two multiplexed signals from the other output port 16b of the multiplexing module 10B are passed through the second combining means 24 without passing through the phase delay means.
Will be guided to.

The second synthesizing means 24 which receives the two multiplexed signals from the respective output ports 16a of the multiplexing modules 10A and 10B has passed through the second delay means 23 from one of the optical time division multiplexing modules 10A. One half of the two-multiplexed signal is guided to the first output port 27a as transmitted light, and the other half is guided to the second output port 27b as reflected light. The second combining means 24 guides one half of the two multiplexed signal from the other optical time division multiplexing module 10B to the first output port 27a as reflected light, and the other half as transmitted light to the second output port 27a. Guide to output port 27b.

Therefore, each of the first and second output ports 2
7a and 27b have two optical time division multiplexing modules 1
Since the 20 Gbps double multiplexed light from 0A and 10B is guided, and the 20 Gbps double multiplexed light from both the first and second output ports 27a and 27b, the second delay means 23 Since the phase difference of a quarter cycle is given to each other, the interleaving of the two multiplexed lights from each of the first and second output ports 27a and 27b causes the first and second output ports 27a and 27b to , 40 Gbps can be derived.

Accordingly, if necessary, four multiplex signals can be extracted from at least one of the first and second output ports 27a and 27b. If necessary, two multiplexed signals from the multiplexing modules 10A and 10B can be extracted from the spare output ports 26a and 26b.

When taking out a two-multiplexed signal from one of the spare output ports 26a or 26b, the two-multiplexed signal is output from the pair of optical time-division multiplexing modules 10A and 10B. One of the extracted optical time-division multiplexing modules 10A or 10A
It is not affected by the operation of the other module 10B or 10A different from OB. Therefore, according to the optical time division multiplexing device 20, in addition to being able to obtain four multiplexed lights, if necessary, regardless of the operation of one of the optical time division multiplexing modules 10 (10A or 10B), Since the superposition of noise from the other module is not received, a good multiplex signal having a large SN ratio can be extracted from the other optical time division multiplexing module 10 (10B or 10A).

In the above description, an example has been shown in which the modulation means uses a light transmission type modulator in which the input port and the output port are functionally separated. However, as the modulator, the input port and the output port are functional. A reflection-type modulator having an input / output port integrated with the optical modulator can be used.

<Embodiment 3> FIG. 3 shows a reflection type modulator 14 '.
Time division multiplexing module 30 using
(30A, 30B). The multiplexing module 30 shown in FIG. 3 comprises a pair of reflection type light modulating means 14 ′ and 15 ′, for example, an electro-absorption type light modulator arranged on the support plate 11, and the module 30. The optical carrier guided to the port 12 is reflected by the two modulation means 1 of the reflection type.
A half mirror 13 'for guiding to each of ports 4d and 15d of 4' and 15 '.

The half mirror 13 'guides one half of the optical carrier from the port 12 as reflected light to the port 14d of one of the reflective modulators 14'. The half mirror 13 'guides the other half of the optical carrier wave from the port 12 to the other reflective modulator 15' as transmitted light. Port 1 from half mirror 13 'to one reflective modulator 14'
Between the optical path length reaching 4d and the optical path length from the half mirror 13 'to the port 15d of the other reflection type modulator 15', the optical carrier passing through both optical paths has a repetition frequency of, for example, four quarters of 10 Gbps. The path difference necessary to give the phase difference of the period (π / 2) is given. In the reflection type, since the optical carrier reciprocates along this path difference, as a result, FIG.
As in the transmission type shown in FIG. 2, a phase difference of a half cycle (π) is provided. Therefore, in Example 3,
This path difference constitutes the same delay means as described above.

Each of the reflection type modulators 14 'and 15' modulates the respective optical carriers inputted to the ports 14d and 15d in accordance with the modulation signals of the respective signal input terminals 14b and 15b, and then modulates the signals. Modulated light to port 1
Return to 4d and 15d respectively. Therefore, in the reflection type modulators 14 'and 15', the ports 14d and 15d
Functions as an input / output port which also functions as an input port and an output port.

Therefore, the reflected light guided from the half mirror 13 'to the reflection type modulator 14' is modulated by the modulator, and the modulated wave is returned to the half mirror 13 '. One half of the modulated wave from the reflection type modulator 14 is guided from the half mirror 13 'to the output port 16 of the optical time division multiplexing module 10 as transmitted light. The other half of the modulated wave from the reflection type modulator 14 is returned to the port 12 as reflected light from the half mirror 13 '.
The transmitted light guided from the half mirror 13 'to the reflection type modulator 15 is modulated by the modulator, and the modulated wave is returned to the half mirror 13'. One half of the modulated wave from the reflection type modulator 15 is the half mirror 1
The light is guided from 3 'to the output port 16 of the optical time division multiplexing module 10 as reflected light. Further, the reflection type modulator 15
Is returned to the port 12 as transmitted light from the half mirror 13 '.

Due to the splitting action of the half mirror 13 ', the modulated waves from the reflection type modulators 14' and 15 'are distributed to the port 12 and the output port 16, respectively. The modulated waves guided to the both ports 12 and the output port 16 reciprocate on the path provided with the path difference described above, thereby being given a phase difference of a half cycle (π) and synthesized. From the port 12 functioning as each input / output port and the output port 16
Multiplexed light can be respectively extracted.

As described above, by using the reflection type modulation means 14 'and 15', the half mirror 13 '
In addition, the function of the branching unit 13, the synthesizing unit, and the dividing unit 17 shown in FIG.
Since the reflection means such as 8a and 18b is not required, the configuration can be simplified, whereby the optical time-division multiplexing module 30 can be provided at a lower cost.

<Embodiment 4> FIG. 4 shows an optical time division multiplexing apparatus 40 using the reflection type optical time division multiplexing modules 30A and 30B shown in FIG. The optical time division multiplexing device 40 includes a substrate 21, a pair of optical time division multiplexing modules 30A and 30B disposed on the substrate, and a half for guiding a carrier wave to the input / output port 12 of each of the modules. And a mirror 22 '. The optical path length from the half mirror 22 'to the input / output port 12 of one reflection type optical time division multiplexing module 30A, and the input / output port 12 of the half mirror 22' from the other reflection type optical time division multiplexing module 30B. The path difference required for giving a repetition frequency, for example, a phase difference of 8 half periods (π / 4) of 10 Gbps to the optical carrier passing through both optical paths is provided between the optical path length and the optical path length. Therefore, Example 4
In this embodiment, the path difference constitutes a delay unit that performs the same function as the delay unit 23 shown in FIG.

When the optical time-division multiplexing device 40 receives a carrier wave of, for example, 10 Gbps as described above at its input port 25, this carrier wave is guided to the half mirror 22 'via the input port 25. In the example shown in FIG. 4, an optical isolator 41 for preventing return of multiplexed light toward the input port 25 is provided as described later.

The half mirror 22 ′ uses the half of the carrier wave from the input port 25 as transmitted light and transmits and receives the half of the carrier wave from the input / output port 12 of one of the reflection type optical time division multiplexing modules 30 A.
To guide. The half mirror 22 ′ guides the other half of the carrier wave from the input port 25 as reflected light to the input / output port 12 of the other reflection type optical time division multiplexing module 30 </ b> B.

The 10 Gbps transmitted carrier guided to the one optical time division multiplexing module 30A is converted into, for example, a 20 Gbps two-multiplexed signal as described in the third embodiment by using the input / output port 12 of the multiplexing module 30A. And output port 16. 20 returned to the input / output port 12 of the optical time division multiplexing module 30A
The 2-Gbps multiplex signal is transmitted by the half mirror 22 '.
One half of the light is guided to the output port 27 of the optical time division multiplexer 40 as reflected light. The other half of the 20 Gbps 2-multiplexed signal returned to the input / output port 12 is guided as transmitted light toward the input port 25, but the optical isolator 41 prevents return to the input port 25.
Further, the two-multiplexed signal guided to the output port 16 of the optical time-division multiplexing module 30A is
0 to the first spare output port 26a.

On the other hand, the 10 Gbps reflected carrier guided to the other optical time-division multiplexing module 30B is converted into, for example, a 20 Gbps two-multiplexed signal by the multiplexing module 30B as in the module 30B. The input / output port 12 and the output port 16 are distributed. The half multiplexed signal of 20 Gbps returned to the input / output port 12 of the optical time-division multiplexing module 30B is guided to the output port 27 by a half mirror 22 'as transmitted light. Also, the input / output port 12
The other half of the 20 Gbps 2-multiplex signal returned to the input port 25 is guided as reflected light toward the input port 25.
Return to the home is prevented. Further, the two-multiplexed signal guided to the output port 16 of the optical time-division multiplexing module 30B is connected to the second spare output port 2 of the optical time-division multiplexing device 40.
6a.

Therefore, in the optical time division multiplexing device 40, the two optical time division multiplexing modules 30 are connected to the output port 27.
A and 30B are guided by two multiplexed lights of 20 Gbps, and both these two multiplexed lights have a half mirror 2
Since a phase difference of a quarter cycle is given to each other by a path difference generated while going back and forth from 2 'to each input / output port, a 40 Gbps 4-multiplexed signal can be derived from the output port 27.

Further, if necessary, the two multiplexed signals from the multiplexing modules 30A and 30B can be transmitted to the spare output ports 26a and 26a without affecting each other.
b.

According to the optical time division multiplexer 40, the half mirror 22 'is connected to the second branching means (22) and the second mirror 22'.
Example 2 because it also functions as the synthesizing means (24)
Can be simplified.

In the example shown in FIG. 4, an example is shown in which an optical isolator 41 is inserted between the input port 25 and the second branching means 22 'to prevent the return of the multiplexed light to the input port 25. However, this isolator is not required, so that the input port 25 can have a function of extracting the second output port of the four-multiplex signal.

<Embodiment 5> FIG. 5 shows still another optical time division multiplexing apparatus 50 according to the present invention using a pair of reflection type optical time division multiplexing modules 30A and 30B. The optical time-division multiplexing device 50 receives the optical carrier from the input port 25 via the optical isolator 41 disposed on the substrate 21 and the same half mirror 22 ′ as described above, and the transmitted light from the half mirror 22 ′ and Optical time-division multiplexing modules 30A and 30B respectively receiving the reflected light are provided.

The transmitted light from the half mirror 22 'is guided to the input / output port 12 of one of the optical time-division multiplexing modules 30A, as in the embodiment 4, and the reflected light from the half mirror 22' is , To the input / output port 12 of the other optical time division multiplexing module 30B.

One half of the double multiplexed light returned to the input / output port 12 of the optical time division multiplexing module 30A is guided to the prism 51 as reflected light of the half mirror 22 '. The output port 16 of the optical time division multiplexing module 30A
Are guided to a switching element 53 such as a variable attenuator via a prism 52, and can be guided to a coupler 54 via the switching element.

One half of the two-multiplexed light returned from the optical time-division multiplexing module 30B to its input / output port 12 is:
The light is guided to the prism 51 as light transmitted through the half mirror 22 ′. Further, the two multiplexed light obtained from the output port 16 of the optical time division multiplexing module 30B is
6b.

Each of the two multiplexed lights guided from each of the optical time division multiplexing modules 30A and 30B to the prism 52 is subjected to a half delay with the same path difference as in the specific example 4 shown in FIG. Since the light is synthesized by the synthesizing action of the mirror 22 ′, the light is guided to the switching element 55 such as a variable attenuator through the prism 52 as the four-multiplex light, and can be guided to the optical coupler 54 through the switching element.

Therefore, each of the switching elements 53 and 5
5, the output port 1 of the four-multiplexed light and the optical time-division multiplexing module 30A is supplied to the optical coupler 54.
6 can be selectively guided, so that the output port 27 of the optical coupler 54 is used as the output port of the optical time-division multiplexing device 50, and the two-multiplexed light and the four-multiplexed light can be selectively selected therefrom. Can be taken out. From this, the switching elements 53 and 55 and the optical coupler 54 constitute switching means for selectively extracting two-multiplexed light and four-multiplexed light from the same port.

The optical path length from the output port 16 of one optical time division multiplexing module 30A to the optical coupler 54 via the switching element 53 and the optical path length from the half mirror 22 'to the optical coupler 54 via the switching element 55 are as follows. ,
They are set equal. The average power of each of the two multiplexed lights obtained from the input / output port 12 of each of the optical time division multiplexing modules 30A and 30B is halved by the half mirror 22 'as transmitted light and reflected light. The average power of the four multiplexed light obtained by multiplexing the two two multiplexed lights is the optical time division multiplexing module 30A.
From the output port 16 of Therefore, the output from the output port 27 'is selectively performed by the switching operation of the switching elements 53 and 55.
A large power difference does not occur between the multiplexed light and the four-multiplexed light, and adverse effects on subsequent optical elements in each switching operation due to the power difference are reliably prevented.

Further, each of the switching elements 53 and 55
As, by using a variable optical attenuator such as the variable attenuator capable of gradually decreasing and gradually increasing the output, the switching operation at the time of switching can be performed gradually, thereby suppressing the occurrence of surging at the time of switching, It is possible to reliably prevent the destruction of the optical element in the latter stage due to the surging.

<Embodiment 6> FIG. 6 shows an example of an optical time division multiplexing apparatus in which a pair of optical time division multiplexing modules are incorporated on a unit substrate. Optical time division multiplexer 6 shown in FIG.
0 denotes a unit substrate 61 and a pair of optical time division multiplexing modules 30 '(30') mounted on the unit substrate.
A, 30'B).

Each optical time division multiplexing module 30 '(3
0'A, 30'B), for example, a 20 Gbps optical carrier wave input to the input / output port 12 on the support plate 11 as in the optical time division multiplexing modules 30A and 30B of the third embodiment shown in FIG. And a half mirror 13 'for guiding to a pair of reflective modulators 14' and 15 '. Each of the optical time division multiplexing modules 30'A and 3 'shown in FIG.
At 0'B, the reflected light of the optical carrier by the half mirror 13 'is guided to the first light modulating means 14' via the prisms 62 and 63, and to the signal input terminal 14b of the first light modulating means. A modulated wave modulated by an input modulation signal (NRZ) of, for example, 20 Gbps is returned to the half mirror 13 'via the prisms 63 and 64.

On the other hand, each optical time division multiplexing module 30 '
At A and 30'B, the optical carrier wave guided from the input / output port 12 to the half mirror 13 'and transmitted through the half mirror 13' is guided to the second optical modulation means 15 'via the prism 64, and A modulated wave modulated by, for example, a 20 Gbps modulation signal (NRZ) input to the signal input terminal 15b of the second optical modulation means is returned to the half mirror 13 'via the prism 64.

The half mirror 13 ′ is, as in the example shown in FIG. 3, a half of the modulated wave from the first light modulating means 14 ′ and the modulated wave from the second modulating means 15 ′. Are returned to the input / output port 12 as reflected light and transmitted light of the half mirror 13 ', respectively. Further, the half mirror 13 ′ is configured to transfer the other half of the modulated wave from the first optical modulator 14 ′ and the other half of the modulated wave from the second modulator 15 ′ to the half mirror 13 ′, respectively. The light is guided to the output port 16 as reflected light and transmitted light. In the example of FIG. 6, an optical isolator 66 is inserted between the half mirror 13 'and the output port 16 to prevent the modulated wave from going backward due to reflection toward the output port or the like. .

The half mirror 13 'receiving the modulated wave from each of the reflection type modulating means 14' and 15 'synthesizes each modulated wave and divides the synthesized wave into each of the ports 12 and 16. When synthesizing the modulated wave by the half mirror 13 ', the half mirror 1
The length of both reciprocating paths from 3 'to each of the reflection type modulators 14' and 15 'is provided for giving a phase difference of, for example, a half cycle (π) of a repetition frequency of 20 Gbps to the optical carrier passing through the two reciprocating paths. Because of the path difference, the delay means causes each port 12 and 16 to interleave the two modulated lights, for example, 40 Gbps.
Are multiplexed. Accordingly, from each port 12 and 16 of each optical time division multiplexing module 30 '(30'A, 30'B), a respective reflection type modulator 14' is provided.
And 15 ', the modulated two-multiplexed signal light can be derived.

The unit substrate 6 of the optical time division multiplexer 60
1 includes an optical carrier of, for example, 20 Gbps from the port 25 ', and each of the optical time-division multiplexing modules 30'A and 30'.
Half mirror 2 divided into 0'B input / output ports 12
2 'is provided. A path from the half mirror 22 'to the input / output port 12 of one optical time division multiplexing module 30'A and a path from the half mirror 22' to the input / output port 12 of the other optical time division multiplexing module 30'B. In the same manner as in the specific example 4 shown in FIG. 4, a repetition frequency of the optical carrier, for example, 20 Gb
A path difference (π / 2 as a round-trip path difference) for providing a phase difference corresponding to eight half periods (π / 4) of ps is given.

Therefore, from the first spare output port 26a provided on the unit board 61, the signal is modulated and multiplexed by the first optical time division multiplexing module 30'A via the output port 16 of the module. For example, 40Gb
The second multiplexed signal light of ps can be derived, and the output port 16 of the second optical time-division multiplexing module 30'B and the prism 69 are output from the second spare output port 26b provided on the unit substrate 61. , For example, 40 Gbps 2 modulated and multiplexed by the module.
Multiplexed signal light can be derived.

Further, from the port 25 'provided on the unit substrate 61, a half mirror 22' serving also as a branching unit, a synthesizing unit and a dividing unit as described above is provided.
E.g. 80 from both modules 30'A and 30'B
A 4-Gbps multiplexed signal light of Gbps can be derived, and a port 25 ′ is output from an output port 27 provided on the unit substrate 61 via a prism 67 and an optical isolator 68.
Similarly to the above, four multiplexed signal lights of, for example, 80 Gbps can be derived.

The two-multiplexed signal light from each of the spare output ports 26a and 26b can be used as a monitor signal if necessary.

<Embodiment 7> FIG. 7 shows Embodiment 6 shown in FIG.
An optical time division multiplexing apparatus 70 that can expand the multiplexing by assembling the required number of optical time division multiplexing apparatuses 60 as a unit is shown. Optical time division multiplexer 70
Comprises a rack 75 provided with shelves 71, 72, 73 and 74 for receiving, for example, four optical time-division multiplexing devices 60 in a stepped manner.

On each of the shelves 71, 72, 73 and 74, the respective unit substrates 61 of the optical time division multiplexing device 60 are arranged in a vertical direction so that they can be taken in and out. The optical time division multiplexers 60 on the shelves 71 and 72 constitute one set, and the optical time division multiplexers 6 on the shelves 73 and 74
0 constitutes another set. In the illustrated example, each of the optical time division multiplexers 60 receives a 20 Gbps modulated signal (NRZ), and supplies, for example, 80 Gbps to each input / output port 25 ′.
A ps 4-multiplexed signal light is output. Although not shown in FIG. 7, each optical time-division multiplexing device 60 can be provided with spare output ports 26a and 26b and an output port 27 similar to those shown in FIG.

When an optical carrier having a repetition frequency of, for example, 20 Gbps is received at the input / output port 76 of the optical time division multiplexing device 70, the third half, which also functions as a branching unit, a synthesizing unit and a dividing unit as described above, is used. Mirror 77
Divides the optical carrier into transmitted light and reflected light.

Of the two divided carrier waves, one half of the optical carrier wave transmitted through the half mirror 77 is guided to the first set of half mirrors 78a, and the transmitted light of the half mirror 78a is positioned below the set. To the input port 25 'of the other optical time division multiplexer 60. The reflected light from the half mirror 78a is guided to the input port 25 'of the other optical time division multiplexing device 60 located above via the prism 79a.

From this, regarding the first set of both optical time division multiplexing devices 60, for example, 80 G
The bps 4-multiplexed signal light is directed to the half mirror 77 via the half mirror 78a.
With respect to 0, between the two devices 60, an optical carrier passing through a reciprocating path from the half mirror 78a to the prism 79a includes, for example, eight half periods (π / 4) of a repetition frequency of 20 Gbps.
As a delay means for giving a phase difference of
a is inserted. Therefore, the four multiplexed optical signals from each input / output port 25 'of the first set of both optical time division multiplexing devices 60 are multiplexed with each other by the delay means 80a, for example, 160 Gbps eight multiplexed signal light. To the half mirror 77.

Further, of the carrier wave split into two by the third half mirror 77, one half of the optical carrier wave reflected by the half mirror 77 is guided to the second half mirror 78b of the second set via the prism 81. You. This half mirror 7
8b guides one half of this carrier as transmitted light to the input port 25 'of one of the optical time division multiplexers 60 located below the set. The half mirror 78b guides the other half of the carrier wave received by the half mirror 78b as reflected light to the input port 25 'of the other optical time division multiplexer 60 located above via the prism 79b.

From this, regarding the second set of both optical time division multiplexers 60, for example, 80 G
The bps 4-multiplexed signal light is directed to the half mirror 77 via the half mirror 78b. Further, with respect to the two optical time division multiplexing devices 60, a spacer 80b constituting the same delay means as described above is inserted between the two devices 60. Therefore, the four multiplexed optical signals from the input / output ports 25 'of the second set of both optical time division multiplexers 60 are multiplexed with each other by the delay means 80b, for example, at 160 Gbps.
Is guided to the half mirror 77 as the 8-multiplex signal light.

The half mirror 77 functions as the synthesizing means and, for interleave processing of both multiplexed optical signals, applies an optical carrier having a repetition frequency of, for example, 20 Gbps to the optical carrier passing through the reciprocating path from the half mirror 77 to the prism 81. Since the path length is set so as to provide a phase difference of a half cycle (π / 8), for example, 3
16 multiplexed signal lights of 20 Gbps are derived.

In the optical time-division multiplexing device 70 described above, an even number of unitized optical time-division multiplexing devices 60 as required are incorporated into shelves 71, 72, 73 and 74 of a rack 75, and By incorporating the prisms 79a and 79b and the half mirrors 78a and 78b, a desired even-multiplexed optical signal can be obtained relatively easily. Further, if necessary, multiplexed light such as 2-multiplexed light and 4-multiplexed light can be extracted as monitor light with a high noise ratio.

In the above description, an example in which an electroabsorption type optical modulator (EA modulator) is used as the modulation means has been described. For example, a lithium niobate Mach-Zehnder optical interferometer type optical modulator (LN modulator) Etc. can be appropriately selected and used. Further, as each delay means, various optical delay means can be applied in addition to an optical crystal element such as a path difference length or lithium niobate.

[0083]

As described above, in the optical time division multiplexing module according to the present invention, the respective modulated lights modulated by the pair of modulating means are given a phase difference to each other, and then are combined with the combining means. The multiplexed signal light is guided to each of the two output ports by the dividing means. Therefore, according to the optical time-division multiplexing module according to the present invention, the two multiplexed signal lights from the two output ports do not affect each other from the viewpoint of noise or the like. Even if the multiplexed signal light from the multiplexed signal is used for multiplexing in the next stage, the multiplexed signal light from the other output port is not affected by the multiplexed signal light. Not
Also, good two-multiplexed light can be obtained irrespective of the operating state of other optical time-division multiplexing modules.

In the optical time-division multiplexing device according to the present invention, as described above, the two multiplexed lights from the one output port of each of the pair of modules are provided with an appropriate time delay, By being multiplexed by the second combining means, the multiplexed light is output as 4-multiplexed light, and in parallel with this, 2-multiplexed light is output from the other output port of each module. Therefore, according to the optical time-division multiplexing device according to the present invention, by assembling a required number of the modules,
It is possible to derive a desired even number multiplexed light. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a pair of optical time division multiplexing modules according to the present invention.

FIG. 2 is a configuration diagram showing an optical time division multiplexing device using a pair of optical time division multiplexing modules according to the present invention.

FIG. 3 is a configuration diagram showing another specific example of the optical time division multiplexing module according to the present invention.

FIG. 4 is a configuration diagram showing an optical time division multiplexing device using the optical time division multiplexing module shown in FIG.

FIG. 5 is a configuration diagram showing still another specific example of the optical time division multiplexing device according to the present invention.

FIG. 6 is a configuration diagram showing still another specific example of the optical time division multiplexing device according to the present invention.

FIG. 7 is a configuration diagram showing an optical time division multiplexing device in which the optical time division multiplexing device shown in FIG. 6 is unitized.

[Explanation of symbols]

10 (10A, 10B), 30 (30A, 30B), 3
0 '(30'A, 30'B) Optical time division multiplexing module 12, 25' Input / output port 13, 13 ', 17, 22, 24, 77, 78a, 78
b Half mirror 14, 14 ', 15, 15' Modulator 14d, 15d Modulator input / output port 16a, 16b Modulator output port

Claims (8)

[Claims] An input port and a plurality of output ports;
Branching means for splitting an optical carrier input to the input port, a pair of modulating means for modulating each of the branched carrier waves obtained by the branching means with a respective modulation signal, and Delay means for giving a mutual phase difference to the modulated light, combining means for combining the two modulated lights provided with the phase difference, and a multiplexed signal light obtained by combining at least two of the output ports. An optical time-division multiplexing module, comprising: a division unit that divides the signal toward one output port. 2. The optical time-division multiplexing module according to claim 1, wherein said combining means and said dividing means are constituted by half mirrors having the functions of both means. 3. The modulating means is a reflection-type modulating means in which an input port of the modulating means also serves as an output port thereof, and the branching means, the synthesizing means and the dividing means have a half functioning as each of these means. 2. The optical time-division multiplexing module according to claim 1, comprising a mirror. 4. The module according to claim 1, wherein the modules are used in pairs, and the arrangement relationship of the input ports and the output ports of the pair of modules is line-symmetric between the pair of modules. Optical time division multiplex module. 5. A first splitting means for splitting an optical carrier from an input port, a pair of modulating means for modulating each split carrier obtained by the splitting means with each modulation signal, First delay means for giving a phase difference between the modulated modulated lights, first combining means for combining the modulated lights given the phase difference, and a multiplexed signal obtained by the combining At least one pair of optical time-division multiplexing modules comprising splitting means for splitting light toward at least two output ports, and a second for guiding an optical carrier to each of the input ports of the optical time-division multiplexing module. Branching means, second delay means for giving a mutual phase difference to the multiplexed light output from one output port of each of the optical time division multiplexing modules, and giving a phase difference. An optical time-division multiplexing device including second combining means for combining the obtained multiplexed lights. 6. A switching unit for selectively extracting multiplexed light from the other output port of one of the optical time division multiplexing modules and multiplexed light from the second combining unit. The optical time division multiplexing device according to claim 5. 7. The switching means, wherein the output port and the output port of the one optical time-division multiplexing module are connected to the other output port and the second combining means via two transmission paths which are equidistant from each other. 7. A coupler for receiving the multiplexed light from each of the second combining means, and a variable optical attenuator inserted in each of the transmission paths to select the multiplexed light output from the coupler. Optical time division multiplexer. 8. The optical time division multiplexing module, the second branching means, and the second combining means are arranged on a unit board which is arranged in a rack in a rack and is insertable. The optical time division multiplexing device according to claim 5.