JPH1146029A - Wavelength multiplex beam signal relaying and amplifying apparatus and optical level regulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical relaying and amplifying apparatus and optical level regulator, which can remove noise through naturally radiated light beam and can regulate optical levels which are differ to a large extent for each wavelength. SOLUTION: A wavelength multiplex optical signal from an optical transmission path 110 is branched into a plurality of different wavelengths by an optical branching circuit 210 and individually output respectively to optical transmission paths 131 to 134. Optical signals branched to individual wavelength by the optical branching circuit 210 are respectively amplified by optical amplifiers 51 to 54, these amplified outputs are combined by an optical coupling circuit 310 and are then returned to the wavelength multiplex optical signal. The optical branching circuit 210 removes the optical signal element other than the waveform multiplexed optical signal and noise element from the preceding stage, while the optical coupling circuit 310 removes noise elements other than the spontaneously emitted light beam and wavelength element other than the branched wavelengths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexed optical signal repeater / amplifier and an optical level adjuster, and more particularly to a wavelength division multiplexed optical signal repeater / amplifier and an optical level adjuster suitable for transmission of wavelength multiplexed light. .

[0002]

2. Description of the Related Art A wavelength multiplexing system for transmitting optical signals having different wavelengths in a single optical fiber collectively enables large-capacity optical transmission. In particular, the emergence of a high-gain, high-output optical amplifier represented by an erbium (Er) -doped optical fiber amplifier (EDFA) enables long-distance, large-capacity optical transmission between fibers. In this optical transmission, when an optical signal is relayed, amplifying the optical signal as it is without converting the optical signal into an electric signal can reduce the size of the relay station and greatly reduce the cost of communication. To contribute. Today, further long-distance optical transmission is expected to be realized by multistage optical repeater amplification.

[0003]

However, according to the conventional wavelength division multiplexing optical signal repeater amplifying apparatus and optical level adjusting apparatus, there are the following problems.

When the number of multiplexed optical signals is large, the optical output per one wave is limited by the output limit of the optical amplifier, and the transmission distance is shortened.

Further, as the number of relay amplifiers increases,
The optical level difference for each wavelength due to the gain deviation of the optical amplifier becomes large, and the receiving sensitivity is remarkably deteriorated due to accumulation of spontaneous emission noise generated from the optical amplifier. In addition, since the gain of the optical amplifier differs for each wavelength, there is a problem that when connected in multiple stages, the optical level greatly differs for each wavelength.

The present invention eliminates noise due to spontaneous emission light from an optical amplifier, which causes deterioration in reception sensitivity, and enables optical transmission using a wavelength multiplexed optical signal with small deterioration in reception sensitivity. It is an object of the present invention to provide a wavelength division multiplexing optical signal repeater / amplifier capable of increasing the output light intensity of the entire signal and equalizing the optical level of each wavelength of the wavelength division multiplexing optical signal.

Another object of the present invention is to provide an optical level which enables a long-distance transmission without converting a wavelength-division multiplexed optical signal into an electric signal, by enabling to arbitrarily adjust an optical level which is largely different for each wavelength. An adjusting device is provided.

[0008]

In order to achieve the above object, the present invention has, as a first feature, a first optical demultiplexer for demultiplexing an input wavelength-division multiplexed optical signal into a plurality of different wavelengths. A plurality of optical amplifiers for amplifying and outputting each of the optical signals demultiplexed by the first optical demultiplexer / multiplexer; and an optical signal of each wavelength amplified by the plurality of optical amplifiers. A second optical demultiplexer / multiplexer for multiplexing and outputting a wavelength multiplexed optical signal;
The present invention provides a wavelength division multiplexing optical signal repeater / amplifier characterized by comprising:

According to a second aspect of the present invention, a wavelength multiplexed optical signal input to an input port is passed to an input / output port, and a wavelength multiplexed optical signal input to the input / output port is provided. An optical circulator that outputs an optical signal from an output port; and an optical circulator that is connected to the input / output port of the optical circulator, outputs a wavelength-division multiplexed optical signal from the optical circulator for each wavelength, and outputs An optical demultiplexer for multiplexing and outputting optical signals having different wavelengths returned from the optical demultiplexer, and connected to respective input / output terminals on the demultiplexing side of the optical demultiplexer, the optical demultiplexer A plurality of bidirectional amplification-type optical amplifiers for amplifying and outputting each optical signal demultiplexed by the multiplexer, and an optical amplifier for reflecting an optical signal output from each of the plurality of optical amplifiers, and Multiple light reflections To provide a wavelength-multiplexed optical signal repeater amplifying apparatus comprising: the chromatography, the.

In order to achieve the above object, the present invention has a third feature that an input wavelength-division multiplexed optical signal is demultiplexed for each wavelength, and light of different wavelengths returned from the demultiplexing side. An optical demultiplexer that multiplexes and outputs a signal; a plurality of first optical transmission paths connected to input / output terminals on a demultiplexing side of the optical demultiplexer / multiplexer; A plurality of optical branching / coupling devices provided at the respective terminal portions of the optical transmission line are connected between different optical branching / coupling devices of the optical branching / coupling device, and the connection is not made in parallel with other connections. And a plurality of bidirectional optical amplifiers provided in each of the plurality of second optical transmission lines and amplifying an optical signal passing therethrough. A wavelength division multiplexing optical signal repeater / amplifier is provided.

According to a fourth aspect of the present invention, there is provided a first optical demultiplexer / demultiplexer for demultiplexing an input wavelength-division multiplexed optical signal for each wavelength. A plurality of optical amplifiers for amplifying each of the optical signals demultiplexed by the optical demultiplexer / multiplexer, and multiplex each of the optical signals amplified by the plurality of optical amplifiers to output a wavelength multiplexed optical signal. An optical level adjusting device comprising: a second optical demultiplexer / multiplexer; and control means for individually controlling gains of the plurality of optical amplifiers.

According to a fifth aspect of the present invention, a wavelength multiplexing optical signal input to an input port is passed through an input / output port, and a wavelength multiplexed optical signal input to the input / output port is provided. An optical circulator that outputs an optical signal from an output port; and an optical circulator that is connected to the input / output port of the optical circulator, outputs a wavelength-division multiplexed optical signal from the optical circulator for each wavelength, and outputs An optical demultiplexer for multiplexing and outputting optical signals having different wavelengths returned from the optical demultiplexer, and connected to respective input / output terminals on the demultiplexing side of the optical demultiplexer, the optical demultiplexer A plurality of bidirectional amplification-type optical amplifiers for amplifying and outputting each optical signal demultiplexed by the multiplexer, and an optical amplifier for reflecting an optical signal output from each of the plurality of optical amplifiers, and Multiple light reflections And a control means for individually controlling at least one of the gain of each of the plurality of optical amplifiers or the reflectance of each of the light reflecting mirrors. .

In order to achieve the above object, the present invention has, as a sixth characteristic, a function of demultiplexing an input wavelength-division multiplexed optical signal for each wavelength and returning light of different wavelengths returned from the demultiplexing side. An optical demultiplexer that multiplexes and outputs a signal; a plurality of first optical transmission lines connected to respective input / output terminals on the demultiplexing side of the optical demultiplexer; A plurality of optical branching / coupling devices provided at the respective terminal portions of the optical transmission line are connected between different optical branching / coupling devices of the optical branching / coupling device, and the connection is not made in parallel with other connections. A plurality of bi-directional optical amplifiers provided in each of the plurality of second optical transmission lines for amplifying an optical signal passing therethrough; and the plurality of optical amplifiers. Control means for individually controlling the respective gains of the light levels. To provide a device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a wavelength division multiplexing optical signal repeater amplifying apparatus and an optical level adjusting apparatus according to the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of a wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

A plurality of different wavelengths (for example, λ ₁ nm = 1
548, λ ₂ = 1550 nm, λ ₃ = 1552 nm, λ
₄ = 1554 nm, and this combination is common in the following embodiments.) An optical demultiplexer 210 is connected to the optical transmission line 110 in which the signal of FIG. The optical demultiplexer 210 is typified by an arrayed waveguide diffraction grating type optical demultiplexer, and splits each of the plurality of different wavelengths into an optical signal having a center of a signal pass band. Each of the four output terminals of the optical demultiplexer 210 has an optical transmission line 1
31, 132, 133, and 134 are connected to each of the optical amplifiers 51 to 54. At each end of the optical transmission lines 131 to 134, the optical transmission lines 131 to
An optical multiplexer 310 for multiplexing the output lights of 134 is connected. The output end of the optical multiplexer 310 is connected to the optical transmission line 12.
0 is connected.

The optical demultiplexer 210 and the optical multiplexer 310 include:
In addition to the arrayed waveguide diffraction grating type, a narrowly-defined optical demultiplexer / multiplexer can be used. Each of the optical amplifiers 51 to 54 is preferably a semiconductor optical amplifier or an impurity-doped optical fiber amplifier. As the impurity-doped optical fiber amplifier, a rare earth-doped optical fiber amplifier such as an erbium-doped optical fiber amplifier, a neodymium-doped optical fiber amplifier, and a praseodymium-doped optical fiber amplifier can be used. These optical fiber amplifiers are appropriately selected and used according to the wavelength band to be used.

In FIG. 1, 15
The 48 nm optical signal is amplified by the optical amplifier 51 and then input to the optical multiplexer 310. By the optical multiplexer 310, the spontaneous emission optical noise of the optical amplifier 51 and the above four wavelengths (λ _{1 to} λ
₄ ) Other wavelengths are removed. That is, the optical multiplexer 310
Has a band-pass filter function for each of the input optical signals. Similarly, the optical transmission lines 132 to 134 through which light of other wavelengths pass are also amplified by the optical amplifiers 52 to 54, and then the optical multiplexer 310
Two to fifty-four spontaneous emission noises and wavelengths other than the four wavelengths are removed. The optical signal of each of these wavelengths is
0 and are combined as a wavelength-division multiplexed optical signal
20. The noise component of the wavelength-division multiplexed optical signal output to the optical transmission line 120 is extremely small, and the amount of deterioration of the receiving sensitivity after transmission is significantly improved.

According to the wavelength division multiplexing optical signal repeater / amplifier of FIG. 1, even when the number of wavelength division multiplexing increases, the optical signal output per one wave is not limited, so that the repeater interval can be made longer. Further, by individually amplifying each wavelength by the optical amplifiers 52 to 54, it is possible to increase the output light intensity of the entire optical signal after wavelength multiplexing as compared to a case where the wavelength multiplexed optical signal is collectively amplified, and The optical level of the optical signal of each wavelength can be made equal.

The spontaneous emission optical noise generated by the optical amplifiers 51 to 54 is removed by the optical multiplexer 310 having a narrow pass band, so that the deterioration of the receiving sensitivity when multi-stage relay amplification is performed is suppressed. be able to. Further, since large-capacity long-distance transmission can be performed without converting an optical signal into an electric signal, it is possible to greatly contribute to a reduction in transmission cost.

Further, the optical demultiplexer 210 and the optical multiplexer 310
Since an array waveguide diffraction grating type is used, the optical waveguide has a narrow band light transmittance, and can multiplex / demultiplex a high-density wavelength-multiplexed optical signal. Further, since it is possible to cope with a high-density wavelength-division multiplexed optical signal, the cost of optical transmission is greatly reduced, and temperature control becomes easy and economical. Further, in the relay facility, the optical signal can be relayed as it is without converting the optical signal into an electric signal, so that the relay facility can be simplified and the cost can be reduced.

In the above embodiment, the number of multiplexed wavelengths on the optical transmission line 110 is four. However, the present invention is not limited to four, and any number such as 8, 16, 32, or 64 can be used. Can be set to a number. Further, the wavelength band of the input light is not limited to the 1550 nm band, but can be freely set to another wavelength band, for example, the 1300 nm band. Further, the optical demultiplexer 210 and the optical multiplexer 31
0 may be an optical multiplexer / demultiplexer.

The optical demultiplexer 210 and the optical multiplexer 310 are not limited to the arrayed waveguide diffraction grating type, but have equivalent functions, such as a wavelength router having a grating structure and a wavelength MUX coupler. The same effect can be expected as long as the combination of the light branching and the interference filter has the same function. An optical demultiplexer 210 represented by an array waveguide diffraction grating type or the like
And the optical multiplexer 310 have different insertion loss for each wavelength,
In order to perform optical level equalization, the optical transmission lines 131 to 13
4, an optical attenuator may be inserted.

(Second Embodiment) FIG. 2 shows a second embodiment of the wavelength division multiplexing optical signal repeater / amplifier of the present invention.

The optical transmission line 110 is connected to one input / output end (input / output port) to which the optical transmission line 121 is connected.
The input terminal (input port) of the optical circulator 60 having one output terminal (output port) to which the output terminal 20 is connected is connected. The output terminal 121 is connected to an optical multiplexer / demultiplexer (optical multiplexer / demultiplexer) 410 having four output terminals for outputting optical signals of the respective wavelengths. Optical transmission lines 131 to 134 are connected to the input / output terminals of the optical multiplexer / demultiplexer 410, respectively.
52, 53, and 54 are inserted and connected.
At each end of 31 to 134, a light reflecting mirror 15 is provided.
1, 152, 153 and 154 are connected. As the optical multiplexer / demultiplexer 410, one represented by an arrayed waveguide diffraction grating type optical multiplexer / demultiplexer can be used.

On the optical transmission line 110, optical signals of the above four wavelengths (λ _{1 to} λ ₄ ) are wavelength-multiplexed. These optical signals pass through the optical circulator 60 and are input to the optical multiplexer / demultiplexer 410. After being demultiplexed into four wavelengths by the optical demultiplexer / demultiplexer 410 and output to the optical transmission lines 131 to 134, they are amplified by the optical amplifiers 51 to 54 for each wavelength. Therefore, each of the optical transmission lines 131 to 134 has only one wavelength of light. Optical amplifiers 51 to 54
The optical signal of each wavelength amplified by
The light is reflected at 154 and travels through the optical amplifiers 51 to 54 in the reverse direction, and enters the optical multiplexer / demultiplexer 410 after re-amplification.

For example, the 15 transmitted to the optical transmission line 131
The optical signal of 48 nm is amplified by the optical amplifier 51, and then reflected by the light reflecting mirror 151.
After that, the signal is again input to the optical multiplexer / demultiplexer 410. The optical multiplexer / demultiplexer 410 removes spontaneous emission optical noise of the optical amplifier 51 and wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ). Optical transmission path 13 through which light of another wavelength passes
The same applies to the optical amplifiers 52 to 54.
After being amplified by the optical reflection mirrors 152 to 154, they are again amplified by the optical amplifiers 52 to 54, and then input to the optical multiplexer / demultiplexer 410 again. The optical multiplexer / demultiplexer 410 multiplexes these optical signals and outputs them to the optical transmission line 120 as a wavelength multiplexed optical signal. The wavelength-multiplexed optical signal passes from the input / output terminal to the output terminal of the optical circulator 60 and is output to the optical transmission line 120. The noise component of the output wavelength-division multiplexed optical signal is extremely small, and the amount of deterioration of the receiving sensitivity after transmission is remarkably improved.

In the wavelength division multiplexing optical signal repeater / amplifier of FIG. 2, the same effects as those of the wavelength division multiplexing optical signal repeater / amplifier of the first embodiment can be obtained. Further, since the light reflecting mirrors 151 to 154 are used, the configuration is simplified, and the wavelength division multiplexing optical signal repeater / amplifier can be configured at low cost.

Further, by using the arrayed waveguide grating type as the optical demultiplexer / demultiplexer 410, the optical demultiplexer 410 has a light transmittance of a narrow bandwidth. Can multiplex. Further, it is possible to cope with a high-density wavelength-division multiplexed optical signal, and the cost for optical transmission can be greatly reduced. Further, temperature control becomes easy and economical.

(Third Embodiment) FIG. 3 shows a wavelength division multiplexing optical signal repeater / amplifier according to a third embodiment of the present invention.

Optical transmission lines 131 to 134 are connected to four output terminals of the optical multiplexer / demultiplexer 410 to which the input optical transmission line 110 and the output optical transmission line 120 are connected. An optical branch (optical branching coupler) 14 is provided at the end of the optical transmission line 131.
4. The optical branch 141 is connected to the terminal of the optical transmission line 132, the optical branch 142 is connected to the terminal of the optical transmission line 133, and the optical branch 143 is connected to the terminal of the optical transmission line 134. Further, an optical amplifier 51 and an optical isolator 71 are connected in series in an optical transmission line 135 connected between the optical branches 144 and 141, and an optical transmission line 1 connected between the optical branches 141 and 142.
The optical amplifier 52 and the optical isolator 72 are connected in series in 36, and the optical amplifier 53 and the optical isolator 73 are connected in series in the optical transmission line 137 connected between the optical branches 142 and 143. The optical amplifier 54 and the optical isolator 74 are provided in the optical transmission line 138 connected between the optical amplifiers 144 and 144.
Are connected in series. The branching ratio of the optical branches 141 to 144 is 1: 1.

The optical signal from the optical transmission line 110 is input to the optical demultiplexer / demultiplexer 410, and the optical signals of the respective wavelengths split here are input to the optical transmission lines 131 to 134. The optical signal output to the optical transmission line 131 will be described. The optical signal is input to the optical amplifier 51 via the optical branch 141,
Optical amplification is performed. The output optical signal of the optical amplifier 51 passes through the optical branch 141 via the optical isolator 71, and is further returned to the optical multiplexer / demultiplexer 410 via the optical transmission line 132.
When an optical signal passes through the optical multiplexer / demultiplexer 410 to the optical transmission line 120, spontaneous emission optical noise of the optical amplifiers 51 to 54 and wavelengths other than the above four wavelengths are removed. That is, the optical demultiplexer 410
Has a bandpass filter function for each wavelength. optical signals of other wavelengths other than λ ₁ (λ ₂ ~λ ₄₎ is also processed in a similar manner.

According to the wavelength division multiplexing optical signal repeater / amplifier of FIG. 3, the noise component of the wavelength division multiplexing optical signal output from the optical transmission line 120 is extremely small, and therefore, the deterioration of the reception sensitivity of the transmission line is remarkably improved. You. Also, the optical multiplexer / demultiplexer 41
0 eliminates spontaneous emission optical noise of the optical amplifiers 51 to 54 and wavelengths other than the above four wavelengths.
The noise component of the above wavelength multiplexed optical signal is extremely small,
Therefore, the amount of reception sensitivity deterioration after transmission is remarkably improved.

In the wavelength division multiplexing optical signal repeater / amplifier of FIG. 3, the same effects as those of the wavelength division multiplexing optical signal repeater / amplifiers of the first and second embodiments can be obtained.

(Fourth Embodiment) FIG. 4 shows a wavelength division multiplexing optical signal repeater / amplifier according to a fourth embodiment of the present invention.

The optical transmission line 110 is connected to an optical amplifier 50 for collectively amplifying all of the wavelength-multiplexed optical signals, and the optical amplifier 50 is connected to an optical demultiplexer 210. The optical demultiplexer 210 is typified by an arrayed waveguide grating optical demultiplexer, and divides the plurality of different wavelengths ([lambda] _{2 to} [lambda] ₄ ) into optical signals centered on a signal pass band. I do.
The four output terminals of the optical demultiplexer 210 have optical transmission lines 131,
132, 133, and 134 are connected, and an optical multiplexer 310 for multiplexing the output lights from the optical transmission lines 131 to 134 is connected to each end. The optical transmission line 120 is connected to the output end of the optical multiplexer 310.

Preferably, a semiconductor optical amplifier or an impurity-doped optical fiber amplifier is used as the optical amplifier 50.
In particular, rare earth-doped optical fiber amplifiers such as an erbium-doped optical fiber amplifier, a neodymium-doped optical fiber amplifier, and a praseodymium-doped optical fiber amplifier are suitable. Also,
As the optical demultiplexer 210 and the optical multiplexer 310, besides the arrayed waveguide diffraction grating type, an optical demultiplexer / multiplexer in a narrow sense can be used.

In the configuration shown in FIG. 4, the optical signal from the optical transmission line 110 is amplified by the optical amplifier 50, and then split by the optical splitter 210 into respective wavelengths.
1 to 134 are output. Since the optical demultiplexer 210 has the filter function as described above, the spontaneous emission optical noise of the optical amplifier 50 and the optical signals of wavelengths other than the four wavelengths are removed (this operation is performed by the optical multiplexer 310). It is also performed in). That is, in each of the optical transmission lines 131 to 134, only an optical signal of only one wavelength exists. The optical signals passing through each of the optical transmission lines 131 to 134 are multiplexed by the optical multiplexer 310 to become a wavelength multiplexed optical signal, which is output to the optical transmission line 120.

According to the wavelength division multiplexing optical signal repeater / amplifier of FIG. 4, the noise component of the output wavelength division multiplexing optical signal is extremely small, and the reception sensitivity deterioration after transmission can be remarkably improved. Therefore, the relay distance can be extended, and the cost of optical transmission can be reduced. In addition, since it is possible to relay the optical signal as it is without converting it into an electric signal, the relay facility can be simplified, and the cost can be reduced.

Further, the optical demultiplexer 210 and the optical multiplexer 31
By using 0 as an arrayed waveguide diffraction grating type, it is possible to obtain a light transmittance of a narrow bandwidth and to multiplex (or combine) a high-density wavelength-multiplexed optical signal. Further, since it is possible to cope with a high-density wavelength-division multiplexed optical signal, optical transmission costs are greatly reduced and temperature control is facilitated.

(Fifth Embodiment) FIG. 5 shows a wavelength division multiplexing optical signal repeater / amplifier according to a fifth embodiment of the present invention. In the figure, the same reference numerals are used for those having the same or the same applications as those in FIG.

The wavelength division multiplexing optical signal repeater / amplifier of FIG. 5 has a configuration in which the optical amplifier 50 is provided at the input end of the optical circulator 60 of FIG. 2 and the optical amplifiers 51 to 54 are removed from the optical transmission lines 131 to 134. I have.

The optical amplifier 50 amplifies the multiplexed optical signal from the optical transmission line 110. The amplified optical signal passes from the input end of the optical circulator 60 to the input / output end, and
The light is demultiplexed into _four wavelengths ([lambda] _{1 to} [lambda] ₄ ) by 10 and output independently to the optical transmission lines 131 to 134, respectively. In the optical multiplexer / demultiplexer 410, the spontaneous emission optical noise of the optical amplifier 50 and the optical signals of wavelengths other than the above four wavelengths are removed as if they passed through the band-pass filters of the respective wavelengths. In this state, each of the optical transmission lines 131 to 134 has only one optical signal of one wavelength. The subsequent flow of the optical signal is the same as that described with reference to FIG.

Also in the wavelength division multiplexing optical signal repeater / amplifier of FIG. 5, the noise component of the wavelength division multiplexing optical signal output to the optical transmission line 120 is extremely small, and therefore, it is possible to remarkably reduce the deterioration of the reception sensitivity after transmission. it can. In addition, the use of an arrayed waveguide grating as the optical multiplexer / demultiplexer 410 provides a narrow-band light transmittance, and the use of one optical multiplexer / demultiplexer enables the demultiplexing of a high-density wavelength-division multiplexed optical signal. Combination becomes possible. Further, since it is possible to cope with a high-density wavelength-division multiplexed optical signal, the cost of optical transmission is greatly reduced, temperature control becomes easy, and economical efficiency is improved. Further, the use of the reflection mirrors 151 to 154 simplifies the configuration and can reduce the cost.

(Sixth Embodiment) FIG. 6 shows a wavelength division multiplexing optical signal repeater / amplifier according to a sixth embodiment of the present invention. In the figure, the same reference numerals are used for those having the same or the same applications as those in FIG. In this embodiment, the optical amplifiers 51 to 54 and the optical isolators 71 to 74 are removed from the optical transmission lines 135 to 138 in FIG. 3, and the optical amplifier 50 is provided on the input side of the optical multiplexer / demultiplexer 410. It has become.

In the configuration shown in FIG. 6, the wavelength multiplexed optical signal from the optical transmission line 110 is amplified by the optical amplifier 50. The output light of the optical amplifier 50 is input to the optical multiplexer / demultiplexer 410, and is split into each wavelength (λ _{1 to} λ ₄ ). At this time, in the optical multiplexer / demultiplexer 410, the spontaneous emission optical noise of the optical amplifier 50 and the optical signal of a wavelength other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed. Each wavelength demultiplexed by the optical demultiplexer / demultiplexer 410 is output to the optical transmission lines 131 to 134, and the adjacent (or other end) optical transmission line (132) via the optical branch provided at each terminal.
To 134, 131), and is returned to the optical multiplexer / demultiplexer 410 through this optical transmission path. Subsequent operations are as described in FIG.

Also in the wavelength division multiplexing optical signal repeater / amplifier of FIG. 6, the noise component of the wavelength division multiplexing optical signal output from the optical transmission line 120 is extremely small. Therefore, it is possible to remarkably improve the reception sensitivity deterioration amount after transmission.

(Seventh Embodiment) FIG. 7 shows a seventh embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention. In the figure, the same reference numerals are used for those having the same or the same application as FIG.

The wavelength division multiplexing optical signal repeater / amplifier of FIG. 7 has a configuration in which the second optical amplifier 51 is provided on the output side of the optical multiplexer 310 in the configuration of FIG. The wavelength multiplexed optical signal is amplified by the optical amplifier 50 in advance, and the multiplexed wavelength multiplexed optical signal is amplified by the optical demultiplexer 210 by the optical amplifier 51. The other configuration is as described with reference to FIG.

The wavelength multiplexed optical signal from the optical transmission line 110 is
After being amplified by the optical amplifier 50, it is input to the optical demultiplexer 210. In this optical demultiplexer 210, λ ₁ , λ ₂ , λ ₃ ,
λ ₄ , and each is divided into optical transmission lines 131 to 131.
134. In the optical demultiplexer 210, the spontaneous emission optical noise of the optical amplifier 50 and the above four wavelengths (λ _{1 to} λ
₄ ) Optical signals of wavelengths other than the above are removed. At this time, in each of the optical transmission lines 131 to 134, only an optical signal of only one wavelength exists. Each optical signal passing through each of the optical transmission lines 131 to 134 is multiplexed by the optical multiplexer 310 to become a wavelength multiplexed optical signal. At this time, the optical multiplexer 3
Also at 10, when each optical signal passes through the waveguide, the spontaneous emission noise of the optical amplifier 50 and the above four wavelengths (λ ₁ to
Optical signals of wavelengths other than λ ₄ ) are removed. Optical multiplexer 3
The wavelength multiplexed optical signal by 10 is subjected to the second amplification by the optical amplifier 51 and output to the optical transmission line 120.

Also in the wavelength division multiplexing optical signal repeater / amplifier of FIG. 7, the noise component of the outputted wavelength division multiplexing optical signal is extremely small, and the deterioration of the receiving sensitivity after transmission can be remarkably improved. Then, the optical amplifier 5 as the second optical amplifier
Since the amplification is performed again in step 1, a sufficient level of wavelength multiplexed optical signal output can be obtained.

(Eighth Embodiment) FIG. 8 shows an eighth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention. In the figure, the same reference numerals are used for those having the same or the same applications as those in FIG. In this embodiment, an optical amplifier 51 is provided on the output side of the optical circulator 60 in FIG. Since the overall operation has been described with reference to FIG. 5, a duplicate description will be omitted here.

In this configuration, the spontaneous emission optical noise and the optical signals having wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed by the optical multiplexer / demultiplexer 410, and further provided on the output side of the optical circulator 60. Since re-amplification is performed on the wavelength-division multiplexed optical signal by the second optical amplifier 51, the noise component of the output wavelength-division multiplexed optical signal is extremely small, and the reception sensitivity deterioration after transmission is significantly improved. A high level of wavelength multiplexed signal output can be obtained.

(Ninth Embodiment) FIG. 9 shows a ninth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention. In the figure, the same reference numerals are used for those having the same or the same applications as those in FIG. This embodiment has a configuration in which the second optical amplifier 51 is provided at the output stage of the optical multiplexer / demultiplexer 410 in FIG. 6, and two optical amplifiers are provided as a whole. The other configuration is the same as that of FIG. 6, and a duplicate description will be omitted.

In the configuration of FIG. 9, the optical multiplexer / demultiplexer 410
As a result, the spontaneous emission optical noise of the optical amplifier 50 and optical signals having wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed.
For example, an optical signal having a wavelength of 1548 nm that has passed through the optical transmission line 131 passes through the optical branch 141 to the optical transmission line 132, passes through the optical transmission line 132, and returns to the optical demultiplexer 410.
Is input to Optical signals of other wavelengths passing through the optical transmission lines 132 to 134 are similarly input to the optical multiplexer / demultiplexer 410. Each optical signal input to the optical demultiplexer / demultiplexer 410 is converted into a wavelength multiplexed optical signal by multiplexing.
After the second amplification, the signal is output to the optical transmission line 120.

In the wavelength division multiplexing optical signal repeater / amplifier of FIG. 9 as well, the noise component of the output wavelength division multiplexing optical signal is extremely small, and the deterioration of the reception sensitivity after transmission can be remarkably improved. In addition, a sufficient level of wavelength multiplexed signal output can be obtained.

(Tenth Embodiment) FIG. 10 shows a tenth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention. In the figure, the same reference numerals are used for those having the same or the same application as FIG. This embodiment has a configuration in which the optical amplifier 50 of the wavelength division multiplexed optical signal repeater / amplifier of FIG. 4 is moved from the input side to the output side.

In this case, since no optical amplifier is provided on the input side, the influence of spontaneous emission optical noise due to the optical amplifier on the input side does not appear. Therefore, in the wavelength division multiplexing optical signal repeater / amplifier of FIG. 10, the spontaneous emission optical noise in the optical amplifier of the other preceding wavelength division multiplexing optical signal repeater / amplifier and the wavelengths other than the above _four wavelengths (λ _{1 to} λ ₄ ). The light signal of
It is removed while passing through the optical multiplexer 310. Also in this case, only one wavelength of light exists in each of the optical transmission lines 131 to 134. The four optical signals that have passed through each of the optical transmission lines 131 to 134 are multiplexed by the optical multiplexer 310 to become a wavelength multiplexed optical signal, further amplified by the optical amplifier 50, and output to the optical transmission line 120. You. The spontaneous emission optical noise generated by the optical amplifier 50 is removed in the optical signal repeater / amplifier provided in the next stage (when the configuration of the present invention is adopted).

Also in the wavelength division multiplexing optical signal repeater / amplifier of FIG. 10, the noise component of the output wavelength division multiplexing optical signal can be reduced, so that the deterioration of the receiving sensitivity after transmission can be remarkably improved.

(Eleventh Embodiment) FIG. 11 shows an eleventh embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention. In the drawing, the same components as those in FIG. 5 are denoted by the same reference numerals. This embodiment has a configuration in which the optical amplifier 50 of FIG. 5 is moved from the input side to the output side. The other configuration is the same as that described with reference to FIG. 5, and the description is omitted here.

Also in this configuration, since the optical amplifier 50 is provided on the output side, the effect of the spontaneous emission optical noise due to the optical amplifier 50 does not appear. Therefore, the spontaneous emission optical noise included in the optical amplifier of the wavelength-division multiplexed optical signal repeater amplifying apparatus and the optical signal of a wavelength other than the above _four wavelengths (λ _{1 to} λ ₄ ) enter the optical multiplexer / demultiplexer 410. / Removed during emission. Each of the optical signals passing through each of the optical transmission paths 131 to 134 is reflected by the light reflecting mirrors 151 to 154, and these reflected optical signals are respectively transmitted to the optical transmission paths 131 to 13.
4 is transmitted in the reverse direction and input to the optical multiplexer / demultiplexer 410 again. The optical multiplexer / demultiplexer 410 multiplexes each optical signal from the optical transmission lines 131 to 134 to generate a wavelength multiplexed optical signal. The wavelength-multiplexed optical signal passes through the optical circulator 60 connected to the optical multiplexer / demultiplexer 410, is amplified by the optical amplifier 50, and is output to the optical transmission line 120. Again,
The spontaneous emission optical noise generated by the optical amplifier 50 is eliminated in the wavelength division multiplexed optical signal repeater / amplifier according to the present invention provided in the next stage.

Also in the wavelength division multiplexing optical signal repeater / amplifier of FIG. 11, the noise component of the output wavelength division multiplexing optical signal can be reduced, so that the deterioration of the receiving sensitivity after transmission can be remarkably improved.

Next, detailed configurations of the optical demultiplexer 120 and the optical multiplexer 140 used in the above embodiment will be described.

FIG. 12 shows a detailed configuration of the optical demultiplexer 120 used in the above embodiment.

The optical demultiplexer 120 is connected to the optical transmission lines 1000, 1
001 to 1004, an optical isolator 1100, an optical branch 1200 provided at the end of the optical transmission line 1000, and an optical transmission line 1001 which is one branch of the optical transmission line 1000.
Optical circulator 1301 provided above, optical transmission line 1
The optical circulator 1302 provided on the optical transmission line 1003 which is the other branch of the optical transmission line 000, and the fiber gratings 1401 and 140 provided on the optical transmission line 1003
3, 1406, and fiber gratings 1402, 1404, and 1405 provided on the optical transmission line 1001.

A plurality of optical signals (λ
₁ , λ ₂ , λ ₂ , λ ₄ ) are wavelength multiplexed. The wavelength multiplexed optical signal passes through the optical isolator 1100 and is split in two directions by an optical branch 1200. For example, the signal of the first wavelength (λ ₁ ) is a fiber grating 1402
The light passes through the optical transmission path 1001 after passing through the optical circulator 1301 and the fiber grating 1405. However, since the signal of the second wavelength (λ ₂ ) is reflected by the fiber grating 1402, it is not output to the optical transmission lines 1001 and 1002. The signal of the _third wavelength (λ ₃ ) is
After passing through the optical circulator 1301 and the optical circulator 1301, the light is reflected by the fiber grating 1405, and is again output to the optical transmission line 1002 via the optical circulator 1301. For other wavelengths λ ₂ and λ ₄ , wavelength division multiplexed light can be similarly demultiplexed.

FIG. 13 shows a detailed configuration of the optical multiplexer 140.

The optical multiplexer 140 is connected to the optical transmission lines 2000 and 2
001 to 2004, a branch 2100 provided at the end of the optical transmission line 2000, an optical circulator 2301 provided on the optical transmission line 2001 which is one branch of the optical transmission line 2000, and one branch of the optical transmission line 2000. Optical circulator 230 provided on optical transmission path 2003 serving as a path
2. Fiber gratings 2202, 2204, 2205 provided on optical transmission line 2001, optical transmission line 200
3, fiber gratings 2201, 2 provided on
203 and 2206.

The optical signal of the _first wavelength (λ ₁ ) input to the optical transmission line 2001 is a fiber grating 2205,
Optical circulator 2301, fiber grating 2
The light is output to the optical transmission line 2000 after passing through the optical branches 204 and 2202 and the optical branch 2100. Further, the optical signal of the _third wavelength (λ ₃ ) input to the optical transmission line 2002 is output to the fiber grating 2205 by the optical circulator 2301, reflected by the fiber grating 2205, and then again to the optical circulator 2301 and the fiber grating 2204 , 2202 and the optical branch 2100 to output to the optical transmission line 2000. Other wavelengths λ ₂ , λ ₄
In the same manner, wavelength multiplexed light can be multiplexed.

In the configurations shown in FIGS. 12 and 13, it is possible to separate (or combine) wavelength-division multiplexed optical signals more densely than an optical multiplexer / demultiplexer using an arrayed waveguide diffraction grating.
Large-capacity optical transmission becomes possible. Here, the optical multiplexer / demultiplexer of FIGS. 12 and 13 is referred to as a fiber grating type in order to distinguish the optical multiplexer / demultiplexer of FIGS. 12 and 13 from the arrayed waveguide diffraction grating type.

(Twelfth Embodiment) FIG. 14 shows a twelfth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

In this embodiment, the optical demultiplexer 210 is replaced with a fiber grating type optical splitter 1501 and the optical multiplexer 310 is replaced with a fiber grating type optical multiplexer 1502 in the configuration of FIG. It has a configuration. The fiber grating type optical demultiplexer 1501 has the configuration shown in FIG.
02 has the configuration shown in FIG.

The optical signals of the above four wavelengths are multiplexed on the optical transmission line 110. These optical signals are input to the fiber grating type optical splitter 1501, split into respective wavelengths, and output to the optical transmission lines 131 to 134. In the fiber grating type optical splitter 1501, the spontaneous emission noise of the optical amplifier before the wavelength division multiplexing optical signal repeater and the optical signal of a wavelength other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed. In each of the paths 131 to 134, only an optical signal of only one wavelength exists. After the respective optical signals on the optical transmission lines 131 to 134 are amplified by the respective optical amplifiers 51 to 54, they are multiplexed by the fiber grating type optical multiplexer 1502,
It becomes a wavelength multiplexed optical signal. In the fiber grating type optical multiplexer 1502, the spontaneous emission optical noise of the optical amplifiers 51 to 54 and optical signals of wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed.

According to the wavelength division multiplexing optical signal repeater / amplifier of FIG. 14, the noise component of the output wavelength division multiplexing optical signal can be made extremely small, so that the deterioration of the reception sensitivity after transmission can be remarkably improved. As a result, the relay distance can be extended, and the cost of optical transmission can be reduced. Also,
Since it can be relayed as it is without converting it to an electric signal,
The relay facility can be simplified, and the cost can be reduced.

Further, since the optical demultiplexer and the optical multiplexer are of the fiber grating type, it is possible to obtain a light transmittance of a narrow bandwidth and to demultiplex (and multiplex) a high-density wavelength-division multiplexed optical signal.
Becomes possible. Furthermore, since it is possible to cope with high-density wavelength-division multiplexed optical signals, the cost of optical transmission can be greatly reduced, temperature control becomes easy, and economical efficiency is improved.

(Thirteenth Embodiment) FIG. 15 shows a thirteenth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention. In this embodiment, the optical multiplexer / demultiplexer 410 shown in FIG.
03. The other configuration is as shown in FIG. Fiber grating type optical multiplexer / demultiplexer 1
Reference numeral 503 denotes a configuration in which the fiber grating type optical demultiplexer of FIG. 12 and the fiber grating type optical multiplexer of FIG. 13 are combined.

Fiber grating type optical multiplexer / demultiplexer 15
In 03, the wavelength division multiplexed light is demultiplexed into each wavelength and output to different optical transmission lines 131 to 134. In the fiber grating type optical multiplexer / demultiplexer 1503, spontaneous emission optical noise of an optical amplifier (not shown) of the preceding wavelength division multiplexing optical signal repeater and an optical signal of a wavelength other than the above four wavelengths (λ _{1 to} λ ₄ ). Is removed. Each of the optical transmission lines 131 to 134 has only an optical signal of only one wavelength. Each optical signal on the optical transmission lines 131 to 134 is
After being amplified by each of the optical transmission lines 131 to 54, the light is reflected by the light reflecting mirrors 151 to 154, passes through the optical amplifiers 51 to 54 again, and is amplified a second time.
Through 134 to the fiber grating type optical multiplexer / demultiplexer 1503. The fiber grating type optical multiplexer / demultiplexer 1503 multiplexes the respective optical signals from the optical transmission lines 131 to 134 into a wavelength multiplexed optical signal. In this fiber grating type optical multiplexer / demultiplexer 1503, the spontaneous emission optical noise of the optical amplifiers 51 to 54 and the four wavelengths (λ _{1 to} λ
₄ ) Optical signals of wavelengths other than the above are removed.

According to the wavelength division multiplexing optical signal repeater / amplifier of FIG. 15, the noise component of the output wavelength division multiplexing optical signal becomes extremely small, and as a result, the reception sensitivity degradation after transmission is remarkably improved. In addition, since the optical multiplexer / demultiplexer 1503 is a fiber grating type optical multiplexer / demultiplexer, light transmission with a narrow bandwidth can be obtained, and a single high-density wavelength-division multiplexed optical signal can be demultiplexed and multiplexed. Can be. Further, since it is possible to cope with a high-density wavelength-division multiplexed optical signal, the cost of optical transmission is greatly reduced, and temperature control becomes easy and economical.
Further, the use of the light reflecting mirrors 151 to 154 simplifies the configuration and can reduce the cost.

(Fourteenth Embodiment) FIG. 16 shows a fourteenth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

In this embodiment, the optical multiplexer / demultiplexer 410 shown in FIG. 3 is replaced with a fiber grating type optical multiplexer / demultiplexer 1.
503. The other configuration is as shown in FIG.

Fiber grating type optical multiplexer / demultiplexer 15
03, when demultiplexing the wavelength-division multiplexed light input from the optical transmission line 110, the spontaneous emission optical noise of the previous
Optical signals of wavelengths other than the wavelength are removed. Thereafter, for example, the optical signal that has passed through the optical transmission line 131 is input again to the fiber grating type optical multiplexer / demultiplexer 1503 through the path of the optical branch (optical branching device) 141 → the optical transmission line 132 →. At this time, the fiber grating type optical multiplexer / demultiplexer 1503
Removes spontaneous emission optical noise of the optical amplifiers 51 to 54 and optical signals of wavelengths other than the above four wavelengths. Optical transmission lines 132 to 13
Optical signals of other wavelengths passing through 4 are similarly input to the fiber grating type optical multiplexer / demultiplexer 1503. Each optical signal input to the fiber grating type optical multiplexer / demultiplexer 1503 is multiplexed and output to the optical transmission line 120 as a wavelength multiplexed optical signal.

Also in this optical signal repeater / amplifier, the noise component of the output wavelength-division multiplexed optical signal becomes extremely small, so that the reception sensitivity deterioration after transmission is remarkably improved.

(Fifteenth Embodiment) FIG. 17 shows a first embodiment of the light level adjusting device according to the present invention.

The optical transmission line 110 has four different wavelengths λ ₁ , λ ₂ , λ ₃ , λ ₄ (wavelengths of 1548 nm, 15
50 nm, 1552 nm, and 1554 nm). An optical splitter 210 is connected to the optical transmission line 110. The optical demultiplexer 210 is typified by an arrayed waveguide diffraction grating type optical demultiplexer, and splits each of the wavelengths λ _{1 to} λ ₄ into an optical signal whose center is a signal pass band. The four output terminals of the optical demultiplexer 210 are connected to the optical transmission line 13.
1, 132, 133 and 134 are connected, and optical amplifiers 51 to 54 are inserted into each of them. Optical transmission path 131
The optical multiplexer 310 for multiplexing the output lights of the optical transmission lines 131 to 134 is connected to each end of the optical multiplexers 131 to 134, and the optical transmission line 120 is connected to the output end of the optical multiplexer 310. . The optical amplifiers 51 to 54 are connected to a control unit 500 as control means for controlling the gain.

The optical signal from the optical transmission line 110 is input to the optical demultiplexer 210 and is demultiplexed into the above four wavelength optical signals. In the optical demultiplexer 210, the spontaneous emission optical noise of the optical amplifier (not shown) of the preceding wavelength division multiplexing optical signal repeater and amplifying device
Wavelengths other than the wavelengths (λ _{1 to} λ ₄ ) are removed. That is, the optical demultiplexer 210 functions as a band-pass filter simultaneously with the demultiplexing function of each wavelength. Such an effect is caused by light of other wavelengths (λ _{2 to} λ) in the optical transmission lines 132 to 134.
₄ ) works in the same way, and after being amplified by the optical amplifiers 52 to 54, the optical multiplexer 310 outputs the signals to the optical amplifiers 52 to 54.
The 54 spontaneous emission noise and wavelengths other than the above three wavelengths are removed. The optical signals of these wavelengths (λ _{1 to} λ ₄ ) are multiplexed by the optical multiplexer 310 and output to the optical transmission line 120 as a wavelength multiplexed optical signal. The optical level of the output wavelength-division multiplexed optical signal is controlled by the control unit 500 by the optical amplifiers 51 to 54.
Can be adjusted by individually controlling the gains, so that an arbitrary light intensity can be adjusted for each wavelength. Control unit 50
At 0, a part of the optical signal for each wavelength outputted from each of the optical amplifiers 51 to 54 is taken out, the optical intensity is monitored, and the monitoring result is fed back to the gain of the optical amplifiers 51 to 54, thereby obtaining an optical signal. The gains of the amplifiers 51 to 54 are controlled.

According to the optical level adjusting device of FIG. 17, by individually controlling the gains of the optical amplifiers 51 to 54, the optical level of the wavelength multiplexed light can be adjusted to an arbitrary intensity for each wavelength.

(Sixteenth Embodiment) FIG. 18 shows a light level adjusting apparatus according to a second embodiment of the present invention.

The optical transmission line 110 is connected to one input / output end (input / output port) to which the optical transmission line 121 is connected.
The input terminal (input port) of the optical circulator 60 having one output terminal (output port) to which the output terminal 20 is connected is connected. The output terminal 121 is connected to an optical multiplexer / demultiplexer 410 having four output terminals for outputting the optical signals of the respective wavelengths. Optical transmission lines 131 to 134 are connected to the input / output terminals of the optical demultiplexer / demultiplexer 410, respectively.
52, 53 and 54 are inserted. Further, at each end of the optical transmission lines 131 to 134, a light reflecting mirror 1 is provided.
51, 152, 153 and 154 are connected. A control unit 500 for adjusting the reflectance is connected to each of the light reflecting mirrors 151 to 154. As the optical multiplexer / demultiplexer 410, one represented by an arrayed waveguide diffraction grating type optical multiplexer / demultiplexer can be used.

The optical signal from the optical transmission line 110 is input to the optical demultiplexer / demultiplexer 410 via the optical circulator 60,
The light is demultiplexed into each wavelength (λ _{1 to} λ ₄ ) by the optical demultiplexer 410 and output to different optical transmission lines 131 to 134, respectively. The optical signals on the optical transmission lines 131 to 134 are amplified by the optical amplifiers 51 to 54, respectively,
The light is reflected by each of the optical amplifiers 1 to 154, re-amplified by the optical amplifiers 51 to 54, and then input to the optical multiplexer / demultiplexer 410. In the optical demultiplexer / demultiplexer 410, the same action as that passed through the band-pass filter is applied to each wavelength at the time of demultiplexing and multiplexing. Therefore, the spontaneous emission optical noise of the optical amplifiers 51 to 54 and the wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed.

For example, the 15 output to the optical transmission line 131
Describing an optical signal of 48 nm, this optical signal is:
After being amplified by the optical amplifier 51, the light reflecting mirror 15
The light is reflected by 1, travels backward, is amplified again by the optical amplifier 51, and is again input to the optical multiplexer / demultiplexer 410. Optical multiplexer / demultiplexer 41
At 0, the spontaneous emission optical noise of the optical amplifier 51 and wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed. The same applies to other wavelengths. The respective optical signals output from the optical amplifiers 51 to 54 are again input to the optical multiplexer / demultiplexer 410 and multiplexed. The optical multiplexer / demultiplexer 410 outputs the multiplexed wavelength-multiplexed optical signal to the optical transmission line 120.

The control unit 500 includes light reflecting mirrors 151 to 1
By controlling the reflectivity of each of the 54 individually, it acts as a kind of attenuator, and can be adjusted to an arbitrary light intensity for each wavelength. In this control, the control unit 520 controls the optical amplifier 51
A part of the optical signal for each wavelength output from each of the optical amplifiers 51 to 54 is taken out, the light intensity is monitored, and based on the result, the reflectance of the light reflecting mirrors 151 to 154 is changed, and each of the optical amplifiers 51 to 54 is changed. Adjust the light intensity of each optical signal to return to.

According to the light level adjusting device of FIG. 18, the wavelengths constituting the wavelength multiplexed light are individually adjusted to an arbitrary intensity by individually controlling the reflectance of the light reflecting mirrors 151 to 154. You.

(Seventeenth Embodiment) FIG. 19 shows a third embodiment of the light level adjusting device according to the present invention.

Optical transmission lines 131 to 134 are connected to the four output terminals of the optical demultiplexer / multiplexer 410 to which the input optical transmission line 110 and the output optical transmission line 120 are connected. An optical branch 144 and an optical transmission line 13 are provided at the end of the optical transmission line 131.
The optical branch 141 is connected to the terminal end of the optical transmission line 133, the optical branch 142 is connected to the terminal end of the optical transmission line 133, and the optical branch 143 is connected to the terminal end of the optical transmission line 134. Further, the optical branches 144 and 14
1 in the optical transmission line 135 connected between
And an optical isolator 71 are connected in series, and an optical amplifier 52 and an optical isolator 72 are connected in series in an optical transmission line 136 connected between the optical branches 141 and 142.
An optical amplifier 53 and an optical isolator 73 are connected in series in an optical transmission line 137 connected between the optical branches 2 and 143, and an optical amplifier 54 and an optical amplifier 54 are installed in an optical transmission line 138 connected between the optical branches 143 and 144. Optical isolators 74 are connected in series. Each of the optical amplifiers 51 to 54 includes a control unit 500.
Is connected. As the optical multiplexer / demultiplexer 410, an optical multiplexer / demultiplexer represented by an arrayed waveguide diffraction grating type optical multiplexer / demultiplexer is used.

The optical signal from the optical transmission line 110 is demultiplexed into the respective wavelengths (λ _{1 to} λ ₄ ) by the optical demultiplexer 410 and output to the optical transmission lines 131 to 134, respectively. For example, an optical signal of wavelength λ ₁ output to the optical transmission line 131 is amplified by the optical amplifier 51, passes through the optical isolator 71, and passes through the optical transmission line 132 connected via the optical branch 141. The signal is input to the optical multiplexer / demultiplexer 410. Optical transmission line 13
Similarly, optical signals of the respective wavelengths passing therethrough are amplified by the optical amplifiers 52 to 54 and then the optical isolator 72
To 74 and the optical transmission lines 133, 134, 131 and input to the optical multiplexer / demultiplexer 410. Optical transmission lines 131 to 134
The optical signals of the respective wavelengths are combined by the optical multiplexer / demultiplexer 410 and output to the optical transmission line 120 as a wavelength multiplexed optical signal. Since the optical multiplexer / demultiplexer 410 has an optical filter function, the spontaneous emission optical noise of the optical amplifiers 51 to 54 and the wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ) reciprocate in each optical signal. Removed.

When passing through the optical branches 141 to 144, the light intensity of the optical signal of each wavelength is controlled in accordance with the control state of the control section 500. The gain of the optical amplifiers 51 to 54 is
00, the light intensity is adjusted for each wavelength. The control unit 500 extracts a part of the optical signal for each wavelength output from each of the optical amplifiers 51 to 54, monitors the optical intensity, and feeds back the gain to the optical amplifiers 51 to 54 based on the result. The gains of the optical amplifiers 51 to 54 are controlled.

According to the optical level adjusting device of FIG. 19, the wavelength multiplexed light can be adjusted to an arbitrary optical level for each wavelength by individually controlling the gains of the optical amplifiers 51 to 54.

(Eighteenth Embodiment) FIG. 20 shows a light level adjusting apparatus according to a fourth embodiment of the present invention.

In FIG. 20, the same reference numerals are used for those that are the same as those in FIG. 18, and duplicate descriptions are omitted here. This configuration is shown in FIG.
The control object of 00 is changed from the light reflection mirrors 151 to 154 to the optical amplifiers 51 to 54. Since other configurations are the same, the description of the entire operation will be omitted.

In this case, the control by the controller 500 controls the gains of the optical amplifiers 51 to 54 individually.
In this case, the control unit 500 extracts a part of the optical signal for each wavelength output from each of the optical amplifiers 51 to 54 and monitors the light intensity.
Feedback to the gains of 1 to 54
4 is controlled.

According to the optical level adjusting device of FIG. 20, by individually controlling the gains of the optical amplifiers 51 to 54, the optical level of the wavelength multiplexed light can be adjusted to an arbitrary intensity for each wavelength.

(Nineteenth Embodiment) FIG. 21 shows a fifth embodiment of the light level adjusting device according to the present invention.

This embodiment is different from the configuration shown in FIG.
In this configuration, a fiber grating type optical splitter 1501 is used instead of the optical splitter 210, and a fiber grating type optical splitter 1502 is used instead of the optical multiplexer 310. Other configurations are as shown in FIG. By using the fiber grating type optical demultiplexer 1501 and the fiber grating type optical demultiplexer 1502, it is possible to manufacture an optical demultiplexer in which the wavelength to be passed is set arbitrarily, and the degree of design freedom is improved. . Also, in the optical level adjusting device having this configuration, since the control section 500 is provided, the gains of the optical amplifiers 51 to 54 can be individually controlled, and the level difference of the optical intensity of the optical signal of each wavelength or the Gain adjustment of the entire level adjustment device can be performed.

(Twentieth Embodiment) FIG. 22 shows a light level adjusting device according to a sixth embodiment of the present invention.

In the present embodiment, the configuration shown in FIG.
The configuration uses a fiber grating type optical multiplexer / demultiplexer 1503 instead of the optical multiplexer / demultiplexer 410. The other configuration is as shown in FIG. By using the fiber grating type optical multiplexer / demultiplexer 1503, it is possible to manufacture an optical multiplexer / demultiplexer in which a wavelength that an optical signal is desired to pass or a wavelength to be reflected is arbitrarily set, thereby improving design flexibility. I do. Also in the light level adjusting device having this configuration, the control unit 500 is provided, and the reflectance of the light reflecting mirrors 151 to 154 can be individually controlled, so that the level difference of the light intensity of the optical signal of each wavelength or the light level Gain adjustment of the entire adjustment device can be performed.

(Twenty-First Embodiment) FIG. 23 shows a seventh embodiment of the light level adjusting device according to the present invention.

In the present embodiment, the configuration shown in FIG.
The configuration uses a fiber grating type optical multiplexer / demultiplexer 1503 instead of the optical multiplexer / demultiplexer 410. The other configuration is as shown in FIG. 19, and the description is omitted. FIG.
According to the configuration 3, by using the fiber grating type optical multiplexer / demultiplexer 1503, it is possible to manufacture an optical multiplexer / demultiplexer in which a wavelength to be passed or a wavelength to be returned is set arbitrarily. The degree of freedom is improved. In the optical level adjusting device having this configuration, the control unit 500 is also provided, and the gains of the optical amplifiers 51 to 54 can be individually controlled. Gain adjustment of the entire adjustment device can be performed.

(Embodiment 22) FIG. 24 shows an eighth embodiment of the light level adjusting device according to the present invention.

The optical level adjusting device shown in FIG. 24 is different from the optical amplifiers 51 to 54 in the configuration shown in FIG.
12, 13, and 14 are provided. Further, the control unit 500 is not provided. The other configuration is the same as that described with reference to FIG. 15, and a duplicate description will be omitted here.

In FIG. 24, the optical signal from the optical transmission line 110 is converted by the optical demultiplexer 210 into the above four waves (λ ₁ to λ ₁ ).
λ ₄ ). The optical demultiplexer 210 removes spontaneous emission optical noise of an optical amplifier (not shown) provided in a device preceding the optical level adjusting device and optical signals of wavelengths other than the above four waves. Optical signals passing through the optical transmission lines 131 to 134 are individually attenuated by optical attenuators 11 to 14 inserted into the optical transmission lines 131 to 134, respectively. Thereby, the light intensity between the wavelengths of the optical signal or between individual wavelengths is adjusted. The optical signals that have passed through the respective terminal portions of the optical transmission lines 131 to 134 are multiplexed by the optical multiplexer 310 to become a wavelength-division multiplexed optical signal, and transmitted to the optical transmission line 120.

According to the optical level adjusting device of FIG. 24, the optical levels of the optical signals of each wavelength of the wavelength multiplexed optical signal output from the optical multiplexer 310 can be arbitrarily set by the optical attenuators 11 to 14. Become.

(Twenty-third Embodiment) FIG. 25 shows a ninth embodiment of the light level adjusting device according to the present invention.

This optical level adjusting device has a configuration in which the optical amplifiers 51 to 54 and the control unit 500 in the configuration of FIG. 20 are removed, and optical attenuators 11 to 14 are provided instead of the optical amplifiers 51 to 54. . Other configurations are the same as those described with reference to FIG. 20 or FIG. 18, and thus redundant description will be omitted here.

In FIG. 25, the optical signal on the optical transmission line 110 passes through the optical circulator 60 and passes through the optical multiplexer / demultiplexer 410.
Are demultiplexed into respective wavelengths by the optical transmission lines 131 to 1 respectively.
34. In the optical multiplexer / demultiplexer 410, the optical amplifier 5
Spontaneous emission optical noise of 0 and optical signals of wavelengths other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed. Optical transmission lines 131 to 134
Are attenuated individually by the optical attenuators 11 to 14, and the light intensity is adjusted between the optical signals or between individual optical signals. Each of the optical signals emitted from the optical attenuators 11 to 14 is reflected by the reflection mirrors 151 to 154, passes through the optical transmission paths 131 to 134 in the opposite direction, and is input to the optical demultiplexer / demultiplexer 410. The optical multiplexer / demultiplexer 410 multiplexes the optical signals from the optical transmission lines 131 to 134 and outputs the multiplexed optical signal to the optical circulator 60. The optical circulator 60 outputs the wavelength multiplexed optical signal from the optical multiplexer / demultiplexer 410 to the optical transmission line 120.

In the optical level adjusting device of FIG. 25, the optical level of the optical signal of each wavelength of the output wavelength multiplexed optical signal is set to an arbitrary optical level by adjusting the optical attenuators 11 to 14. Therefore, it is possible to adjust a light level that is significantly different for each wavelength.

(Twenty-fourth Embodiment) FIG. 26 shows a tenth embodiment of the light level adjusting device according to the present invention.

The optical level adjusting device of FIG. 26 has the same configuration as that of FIG.
And the optical isolators 71 to 74 are removed, and the optical transmission line 13 is removed.
The optical attenuators 11 to 14 are provided in each of the elements 5 to 138. The other configuration is the same as that described with reference to FIG.

In the configuration shown in FIG. 26, the optical signal from the optical transmission line 110 is input to the optical demultiplexer / demultiplexer 410, and
Wavelengths (λ _{1 to} λ ₄ ). Optical multiplexer / demultiplexer 4
In step 10, the spontaneous emission optical noise included in the optical signal of each wavelength and the optical signal of a wavelength other than the above four wavelengths (λ _{1 to} λ ₄ ) are removed. The optical signal of each wavelength demultiplexed by the optical demultiplexer / demultiplexer 410 is
The optical attenuator 11 passes through the optical transmission lines 131 to 134 individually.
The attenuation of the individual light intensity is performed by. For example, an optical signal having a wavelength of 1548 nm that passes through the optical transmission line 131 is attenuated by the optical attenuator 11, then travels through the optical branch 141 to the optical transmission line 132, and passes through the optical transmission line 132 again. The signal is input to the multiplexer 410. Optical transmission line 132-
Optical signals of other wavelengths passing through 134 are similarly input to the optical demultiplexer / demultiplexer 410. Each optical signal input to each optical splitter 410 is multiplexed into a wavelength multiplexed optical signal,
Output to the optical transmission line 120.

In the optical level adjusting device of FIG. 26 as well, the optical level of the optical signal of each wavelength of the output wavelength multiplexed optical signal can be set to an arbitrary optical level.

In each of the above light level adjusting devices,
Although one of the optical amplifier and the optical attenuator is used, a configuration in which both are mixed may be used.

[0121]

As described above, the wavelength division multiplexing optical signal repeater / amplifier of the present invention demultiplexes an input wavelength division multiplexing optical signal into respective wavelengths, and then amplifies the wavelength division multiplexed optical signal with an optical amplifier for each wavelength. Since it is output as a post-wavelength multiplexed optical signal, the output light intensity of the entire optical signal after wavelength multiplexing can be increased as compared with a case where the wavelength-multiplexed optical signal is collectively amplified, and the optical signal of each wavelength can be output. Light levels can be equalized.

In a fiber grating type optical demultiplexer, an optical multiplexer, or a wavelength division multiplexing optical signal repeater using an optical multiplexer / demultiplexer, light transmittance of a narrow bandwidth is obtained and high density is obtained. Can be split (or multiplexed). Furthermore, since it is possible to cope with high-density wavelength-division multiplexed optical signals, the cost of optical transmission can be greatly reduced, temperature control becomes easy, and economical efficiency is improved.

The spontaneous emission optical noise generated from the optical amplifier accumulates as the optical amplifiers are connected in multiple stages, and the receiving sensitivity is significantly deteriorated. Since the filter functions as a filter, spontaneous emission optical noise generated from the optical amplifier can be removed, and optical transmission with small deterioration in reception sensitivity can be realized.
As a result, long-distance transmission can be performed without converting a wavelength-division multiplexed optical signal into an electric signal.

Further, the optical level adjusting device according to the present invention amplifies the optical signal by the optical amplifier for each demultiplexed wavelength and adjusts the gain or controls the reflectance of the light reflecting mirror. By changing the gain of the optical amplifier, the optical intensity of the optical signal of the wavelength to be amplified can be individually adjusted. Therefore, the optical level of each wavelength of the wavelength multiplexed optical signal can be adjusted to an arbitrary intensity.

Further, in a fiber grating type optical demultiplexer, an optical multiplexer, or an optical level adjusting device using an optical multiplexer / demultiplexer, a narrow pass bandwidth can be obtained and a high-density wavelength division multiplexed optical signal can be demultiplexed. (Or multiplexing), the cost of optical transmission can be greatly reduced, the optical level adjustment and temperature control become easy, and the economy is improved.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing a first embodiment of a wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 2 is a connection diagram showing a second embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 3 is a connection diagram showing a third embodiment of the wavelength division multiplexing optical signal relay amplifier according to the present invention.

FIG. 4 is a connection diagram showing a fourth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 5 is a connection diagram showing a fifth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 6 is a connection diagram showing a sixth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 7 is a connection diagram showing a seventh embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 8 is a connection diagram showing an eighth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 9 is a connection diagram showing a ninth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 10 is a connection diagram showing a tenth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 11 is a connection diagram showing an eleventh embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 12 is a connection diagram showing a detailed configuration of an optical demultiplexer according to the present invention.

FIG. 13 is a connection diagram showing a detailed configuration of an optical multiplexer according to the present invention.

FIG. 14 is a connection diagram showing a twelfth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 15 is a connection diagram illustrating a thirteenth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 16 is a connection diagram showing a fourteenth embodiment of the wavelength division multiplexing optical signal repeater / amplifier according to the present invention.

FIG. 17 is a connection diagram showing a first embodiment of the light level adjusting device according to the present invention.

FIG. 18 is a connection diagram showing a second embodiment of the light level adjusting device according to the present invention.

FIG. 19 is a connection diagram showing a third embodiment of the light level adjusting device according to the present invention.

FIG. 20 is a connection diagram showing a fourth embodiment of the light level adjusting device according to the present invention.

FIG. 21 is a connection diagram showing a fifth embodiment of the light level adjusting device according to the present invention.

FIG. 22 is a connection diagram illustrating a light level adjusting device according to a sixth embodiment of the present invention.

FIG. 23 is a connection diagram illustrating a light level adjusting device according to a seventh embodiment of the present invention.

FIG. 24 is a connection diagram showing an eighth embodiment of the light level adjusting device according to the present invention.

FIG. 25 is a connection diagram showing a ninth embodiment of the light level adjusting device according to the present invention.

FIG. 26 is a connection diagram showing a tenth embodiment of the light level adjusting device according to the present invention.

[Explanation of symbols]

 11 to 14 optical attenuator 50, 51 to 54 optical amplifier 60, 1301, 1302 optical circulator 71 to 74, 1100 optical isolator 110, 120, 121, 131 to 138 optical transmission path 141 to 144, 1200 optical branching (optical branching and coupling) Device) 151 to 154 light reflecting mirror 210 optical demultiplexer 310 optical demultiplexer 410 optical demultiplexer (optical demultiplexer / demultiplexer) 500 control unit 1000 to 1004, 2000 to 2004 optical transmission path 1401 to 1406 fiber grating 1501 Fiber grating type optical demultiplexer 1502 Fiber grating type optical demultiplexer 1503 Fiber grating type optical demultiplexer

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04B 10/02 10/18

Claims (44)

[Claims] 1. A first optical demultiplexer / demultiplexer for demultiplexing an input wavelength-multiplexed optical signal into a plurality of different wavelengths, and an optical signal demultiplexed by the first optical demultiplexer / demultiplexer. A plurality of optical amplifiers each of which amplifies and outputs, a second optical demultiplexer / multiplexer that multiplexes the optical signals of each wavelength amplified by the plurality of optical amplifiers and outputs a wavelength multiplexed optical signal; A wavelength division multiplexing optical signal repeater / amplifier, comprising: 2. The optical amplifier according to claim 1, wherein the plurality of optical amplifiers are connected by using an optical transmission line between the first optical demultiplexer / multiplexer and the second optical demultiplexer / multiplexer. The wavelength division multiplexing optical signal repeater / amplifier according to claim 1. 3. The wavelength division multiplexing optical signal repeater / amplifier according to claim 1, wherein said plurality of optical amplifiers are semiconductor optical amplifiers or impurity-doped optical fiber amplifiers. 4. The optical multiplexer / demultiplexer according to claim 1, wherein the first optical multiplexer / demultiplexer is an optical multiplexer, and the second optical multiplexer / demultiplexer is an optical multiplexer. Wavelength multiplexing optical signal repeater / amplifier. 5. The wavelength division multiplexing optical signal repeater / amplifier according to claim 1, wherein said first and second optical demultiplexers / multiplexers are of an arrayed waveguide diffraction grating type. 6. The wavelength division multiplexing optical signal repeater / amplifier according to claim 1, wherein said first and second optical demultiplexers / multiplexers are of a fiber grating type. 7. An optical circulator for passing a wavelength multiplexed optical signal input to an input port to an input / output port and outputting a wavelength multiplexed optical signal input to the input / output port from an output port; Connected to the input / output port, the wavelength multiplexed optical signal from the optical circulator is demultiplexed for each wavelength and output, and optical signals of different wavelengths returned from the demultiplexing side are multiplexed and output. An optical demultiplexer / demultiplexer, which is connected to each input / output end on the demultiplexing side of the optical demultiplexer / demultiplexer, and amplifies each optical signal demultiplexed by the optical demultiplexer / demultiplexer. A plurality of bidirectional amplification type optical amplifiers for outputting, and a plurality of light reflection mirrors for reflecting optical signals output from each of the plurality of optical amplifiers and returning the optical signals to the respective optical amplifiers. Wavelength multiplexing optical signal relay Width equipment. 8. The wavelength division multiplexing optical signal repeater / amplifier according to claim 7, wherein said optical demultiplexer / multiplexer is of an arrayed waveguide diffraction grating type. 9. The wavelength division multiplexing optical signal repeater / amplifier according to claim 7, wherein said optical demultiplexer / multiplexer is of a fiber grating type. 10. The fiber grating type optical demultiplexer / demultiplexer includes at least one fiber grating provided on an optical transmission line, and an optical signal from the fiber grating or the fiber grating provided on the optical transmission line. 11. The wavelength division multiplexing optical signal repeater / amplifier according to claim 10, further comprising: an optical circulator for selectively inputting / outputting an optical signal to / from the optical amplifier. 11. A wavelength division multiplexing optical signal repeater amplifier according to claim 7, wherein said optical amplifier is connected between said optical demultiplexer / multiplexer and said optical reflection mirror using an optical transmission line. apparatus. 12. The wavelength division multiplexing optical signal repeater / amplifier according to claim 7, wherein said optical amplifier is a semiconductor optical amplifier or an impurity-doped optical fiber amplifier. 13. The optical fiber amplifier according to claim 1, wherein:
13. The wavelength division multiplexing optical signal repeater / amplifier according to claim 12, wherein the amplifier is a rare earth doped optical fiber amplifier. 14. The rare earth-doped optical fiber amplifier,
14. The wavelength division multiplexed optical signal repeater amplifier according to claim 13, wherein the amplifier is an erbium-doped optical fiber amplifier, a neodymium-doped optical fiber amplifier, or a praseodymium-doped optical fiber amplifier. 15. An optical demultiplexer / demultiplexer, which demultiplexes an input wavelength-division multiplexed optical signal for each wavelength, and multiplexes and outputs optical signals of different wavelengths returned from the demultiplexing side. A plurality of first optical transmission lines connected to each of the input / output terminals on the demultiplexing side of the optical demultiplexer / multiplexer; and a plurality of optical branches provided at respective terminal portions of the plurality of optical transmission lines A second plurality of optical transmission lines that connect different optical branching couplers of the optical branching coupler and that are not connected in parallel with other connections; and A wavelength division multiplexing optical signal repeater / amplifier, comprising: a plurality of bidirectional optical amplifiers provided in each of the second optical transmission lines to amplify a passing optical signal. 16. The wavelength division multiplexing optical signal repeater / amplifier according to claim 15, wherein each of the plurality of second optical transmission lines is provided with an optical isolator. 17. The wavelength division multiplexing optical signal repeater / amplifier according to claim 15, wherein said optical amplifier is a semiconductor optical amplifier or an impurity-doped optical fiber amplifier. 18. The optical fiber amplifier according to claim 1, wherein:
16. The wavelength division multiplexed optical signal repeater / amplifier according to claim 15, wherein the device is a rare earth doped optical fiber amplifier. 19. The rare earth-doped optical fiber amplifier,
16. The wavelength division multiplexed optical signal repeater / amplifier according to claim 15, which is an erbium-doped optical fiber amplifier, a neodymium-doped optical fiber amplifier, or a praseodymium-doped optical fiber amplifier. 20. The optical demultiplexer / demultiplexer according to claim 1, wherein the optical demultiplexer / demultiplexer is an arrayed waveguide diffraction grating type optical demultiplexer / demultiplexer.
6. The wavelength division multiplexing optical signal repeater / amplifier according to 5. 21. The wavelength division multiplexing optical signal repeater / amplifier according to claim 15, wherein said optical demultiplexer / multiplexer is of a fiber grating type. 22. A first optical demultiplexer / demultiplexer for demultiplexing an input wavelength-division multiplexed optical signal for each wavelength, and an optical signal demultiplexed by the first optical demultiplexer / demultiplexer. A plurality of optical amplifiers for amplifying a plurality of optical amplifiers; a second optical demultiplexer / multiplexer for multiplexing each of the optical signals amplified by the plurality of optical amplifiers and outputting a wavelength-multiplexed optical signal; And a control means for individually controlling each gain of the light level adjusting device. 23. The optical amplifier according to claim 21, wherein the optical amplifier is connected between the first optical demultiplexer / multiplexer and the second optical demultiplexer / multiplexer using an optical transmission line. 23. The light level adjusting device according to 22. 24. The optical level adjusting device according to claim 22, wherein said plurality of optical amplifiers are semiconductor optical amplifiers or impurity-doped optical fiber amplifiers. 25. The optical multiplexer / demultiplexer according to claim 22, wherein the first optical multiplexer / demultiplexer is an optical multiplexer, and the second optical multiplexer / demultiplexer is an optical multiplexer. Light level adjustment device. 26. The optical level adjusting device according to claim 22, wherein the optical demultiplexer / multiplexer is an arrayed waveguide diffraction grating type. 27. The optical level adjusting device according to claim 22, wherein said optical demultiplexer / multiplexer is of a fiber grating type. 28. The optical level adjusting device according to claim 22, wherein a plurality of optical attenuators are provided instead of the plurality of optical amplifiers or in series. 29. An optical circulator for passing a wavelength-division multiplexed optical signal input to an input port to an input / output port and outputting a wavelength-division multiplexed optical signal input to the input / output port from an output port; Connected to the input / output port, the wavelength multiplexed optical signal from the optical circulator is demultiplexed for each wavelength and output, and optical signals of different wavelengths returned from the demultiplexing side are multiplexed and output. An optical demultiplexer / demultiplexer, which is connected to each input / output end on the demultiplexing side of the optical demultiplexer / demultiplexer, and amplifies each optical signal demultiplexed by the optical demultiplexer / demultiplexer. A plurality of optical amplifiers of a bidirectional amplification type for outputting, a plurality of light reflecting mirrors for reflecting optical signals output from each of the plurality of optical amplifiers and returning the optical signals to the respective optical amplifiers; and each of the plurality of optical amplifiers Gain, also Optical level adjusting device, characterized in that and a control means for individually controlling at least one of each of the reflectivity of the light reflecting mirror. 30. The optical level adjusting device according to claim 29, wherein the optical amplifier is connected between the optical demultiplexer / multiplexer and the plurality of light reflecting mirrors using an optical transmission line. 31. The optical level adjustment device according to claim 29, wherein said plurality of optical amplifiers are semiconductor optical amplifiers or impurity-doped optical fiber amplifiers. 32. The impurity-doped optical fiber amplifier,
30. The optical level adjusting device according to claim 29, wherein the optical level adjusting device is a rare earth doped optical fiber amplifier. 33. The rare earth-doped optical fiber amplifier,
33. The optical level adjusting device according to claim 32, wherein the optical level adjusting device is any one of an erbium-doped optical fiber amplifier, a neodymium-doped optical fiber amplifier, and a praseodymium-doped optical fiber amplifier. 34. The optical level adjusting device according to claim 29, wherein a plurality of optical attenuators are provided instead of the plurality of optical amplifiers or in series. 35. The optical demultiplexer / demultiplexer according to claim 2, wherein the optical demultiplexer / demultiplexer is an arrayed waveguide diffraction grating type optical demultiplexer / demultiplexer.
10. The light level adjusting device according to 9. 36. The optical level adjusting device according to claim 29, wherein the optical demultiplexer / multiplexer is of a fiber grating type. 37. An optical demultiplexer / multiplexer for demultiplexing an input wavelength-division multiplexed optical signal for each wavelength and multiplexing and outputting optical signals of different wavelengths returned from the demultiplexing side. A plurality of first optical transmission lines connected to each of the input / output terminals on the demultiplexing side of the optical demultiplexer / multiplexer; and a plurality of optical branches provided at respective terminal portions of the plurality of optical transmission lines A second plurality of optical transmission lines that connect different optical branching couplers of the optical branching coupler and that are not connected in parallel with other connections; and A plurality of bidirectional optical amplifiers provided in each of the second optical transmission lines for amplifying an optical signal passing therethrough; and control means for individually controlling gains of the plurality of optical amplifiers, respectively. A light level adjusting device, comprising: 38. The optical level adjustment device according to claim 37, wherein each of said plurality of second optical transmission lines is provided with an optical isolator. 39. The optical level adjusting device according to claim 37, wherein the plurality of optical amplifiers are semiconductor optical amplifiers or impurity-doped optical fiber amplifiers. 40. The optical level adjusting device according to claim 37, wherein a plurality of optical attenuators are provided instead of the plurality of optical amplifiers or in series. 41. The impurity-doped optical fiber amplifier,
The optical level adjusting device according to claim 37, wherein the optical level adjusting device is a rare earth-doped optical fiber amplifier. 42. The rare earth-doped optical fiber amplifier,
The optical level adjusting device according to claim 41, wherein the optical level adjusting device is an erbium-doped optical fiber amplifier, a neodymium-doped optical fiber amplifier, or a praseodymium-doped optical fiber amplifier. 43. The optical demultiplexer / demultiplexer according to claim 3, wherein the optical demultiplexer / demultiplexer is an arrayed waveguide diffraction grating type optical demultiplexer / demultiplexer.
8. The light level adjusting device according to 7. 44. The optical level adjusting device according to claim 37, wherein the optical demultiplexer / multiplexer is of a fiber grating type.