JPH11174383A - Optical isolator circuit and optical amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical amplifier which can collectively amplify wavelength-multiplex signal lights of >=3 wavelength channels having arbitrary propagation directions. SOLUTION: The optical amplifier is equipped with a small number of optical amplifying means less than the wavelength channels for signal lights propagated over >=3 wavelength channels having the propagation directions set by the wavelength channels in the same coated optical fiber and an optical isolator means which optically branch and couple signal lights of the respective wavelength channels and isolate them in the propagation directions before or/and behind the optical amplifying means. The optical isolator circuit used for it is constituted by mutually connecting input/output ports corresponding to the same wavelength channel on the side where waveguides are branched by the wavelength channels of two 1:N branch type optical wavelength multiplexing and demultiplexing circuit and arranging the optical isolators on the waveguides corresponding to the wavelength channels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel optical amplifier for communication and an optical isolator circuit.

[0002]

2. Description of the Related Art The configuration of a conventional optical amplifier is as shown in FIGS. That is, since there is a reflection point of an optical signal such as a connector connection point on a general optical transmission line, in order to intercept these reflected lights and stably perform optical amplification,
Optical isolator circuits that limit the propagation of signal light to only the desired optical transmission direction are arranged before and after the optical amplifier. Therefore, even when optically amplifying a wavelength multiplexed optical signal, the propagation directions are all in the same direction. Is restricted to

An optical isolator used in this optical isolator circuit has an optical fiber having a function of restricting the propagation direction of signal light to only one direction, ie, upward or downward. That is, the function of uniformly restricting the propagation direction of the signal light of all the wavelength channels to the wavelength multiplexed signal light is provided.

As an optical amplifier, which is a component of the optical amplifier, generally, bidirectional pumping of the rare-earth-doped optical fiber 4 by a pumping semiconductor laser 5 (FIG. 2A) and forward pumping (FIG. 2)
(b)), backward pumping (FIG. 2 (c)), or a semiconductor-type optical amplifier 8 (FIG. 2 (d)). The rare-earth-doped optical fiber 4 is usually made of quartz glass, Zr-based fluoride glass and telluride-based glass are used as hosts for the purpose of expanding the amplification wavelength band, and Er ³⁺ is used for the 1.5 × 10 ⁻⁶ m band and is used for the 1.3 × 10 ⁻⁶ m band. It is known from Yamada et al. From the 1995 Fall IEICE Transactions, C-216, and A.Mori et al., OFC'97, PDP1, etc. that Pr ³⁺ is used as an added rare earth.

In recent years, a bidirectional optical amplifier having a configuration as shown in FIGS. 3 and 4 has been proposed. An optical amplifier having the configuration shown in FIG. 3 (for details, see ECOC'96TuD.2.2 by K. Aida et al.). However, there is a problem that the amplifier oscillates when there is a reflection point. Therefore, there is no reflection point on the transmission line optical fiber and a special circulator using an optical circulator for the transmission / reception unit of the optical signal. There is a problem that the optical amplifier can be used only in the optical transmission system having the configuration, and the optical amplifier having the configuration in FIG. 4 requires each wavelength in order to realize an optical amplifier that can arbitrarily set up and down in the transmission direction for each wavelength channel. It is necessary to provide a conventional optical amplifier for each channel, and as a result, as the number of wavelength channels increases, the overall size and cost increase. Therefore, it is practical as an optical amplifier for bidirectional WDM signal light having a large number of wavelength channels. Absent.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to collectively combine wavelength multiplexed signal lights of three or more wavelength channels that propagate in the same optical fiber and have arbitrary propagation directions with respect to the upstream and downstream directions. An optical isolator circuit capable of amplifying and removing an optical signal generated in a wavelength region other than each wavelength channel and isolating the signal light of each wavelength channel in a propagation direction determined for each wavelength. Another object of the present invention is to provide an optical amplifier having a function of arbitrarily adjusting the signal strength of each wavelength channel and an optical isolator circuit that can be used for the optical amplifier.

[0007]

In order to achieve the above object, an optical amplifier according to the present invention has three or more channels in which the upward or downward propagation direction is set for each wavelength channel in the same optical fiber. For the signal light propagating through a plurality of wavelength channels, the number of optical amplifiers smaller than the number of wavelength channels, and before, after or before or after the optical amplifier, the branch coupling and propagation direction of the signal light of each wavelength channel. An optical isolator for performing isolation is provided.

In the optical amplifier according to the present invention, an optical coupling / branching circuit for branching from one optical waveguide into individual optical waveguides for each wavelength channel, an optical isolator disposed in the branched individual optical waveguides, and the individual optical waveguides are provided. It can be configured to include an optical isolator unit having an optical multiplexing / branching circuit for coupling a waveguide to one optical waveguide, and one optical amplifying unit for amplifying all coupled signal lights. Similarly, an optical multiplexing / branching circuit that branches from one optical waveguide into individual optical waveguides for each wavelength channel, an optical isolator arranged in the branched individual optical waveguide, and the individual optical waveguide is coupled to a plurality of optical waveguides. And a plurality of optical amplifying means for amplifying signal light for each of the plurality of optical waveguides.

Further, in the optical amplifier of the present invention, an optical multiplexing / branching circuit for branching from one optical waveguide into individual optical waveguides for each wavelength channel, and separating the individual branched optical waveguides into wavelength channels for each wavelength channel group. An optical isolator means comprising one or more optical coupling / branching circuits respectively coupled to a number of optical waveguides equal to or less than the number, and optical isolators arranged in the coupled one or more optical waveguides;
Alternatively, it may be configured to include one or a plurality of optical amplification means for amplifying the signal light for each of the plurality of optical waveguides.

Further, in the optical isolator circuit of the present invention which can be used in the optical amplifier of the present invention, the waveguide is branched for each wavelength channel of the two 1-to-N branch type optical wavelength multiplexing / demultiplexing circuits. Side, the input and output ports corresponding to the same wavelength channel are connected to each other, and on the waveguide corresponding to each wavelength channel so that propagation is restricted only in the direction determined by each wavelength channel. It has a configuration including an optical circuit in which an optical isolator is arranged.

In the present invention, as an optical wavelength multiplexer / demultiplexer, an AWG (array waveguide type optical multiplexer / demultiplexer, specifically, KO
Kamoto et al.'s OFC'95 ThB.1) can be used. If a plurality of AWGs are used in combination, even if the interval between adjacent wavelength channels is very narrow and the number of wavelength channels is as large as several tens, wavelength channels can be easily combined with low loss. In addition, it is possible to easily realize an optical circuit configuration having a complicated multiplexing / branching function such as arranging wavelength channels in an arbitrary group and multiplexing / branching.

Further, according to such a configuration, the net optical gain of the optical amplifier can be improved, so that unnecessary optical signals generated in a wavelength region other than each wavelength channel can be removed. Furthermore, if a variable optical intensity adjuster is inserted for each wavelength channel into the circuit section that separates the signal light before and after the optical amplifier for each wavelength channel, the signal light for each channel can be individually adjusted. it can.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 6 is a diagram showing a configuration of an optical isolator circuit according to a first embodiment of the present invention. In this circuit, each channel has an arbitrary upward or downward propagation direction and a wavelength of each channel. , AN, b1,..., AN, b1,.
Of the b2,..., bM}, wavelength channel groups {a1, a2,..., aN} in which the propagation direction is the same in the forward direction and wavelength channel groups {b1, b} in which the propagation directions are the same in the reverse direction.
2,..., BM}, each of which is an optical isolator circuit having input and output ports, and input and output ports A and B serving as output and input ports, respectively. A, output ports {c: a1, c: a2,..., C: aN} corresponding to each wavelength channel {a1, a2,.
Input ports {c: b corresponding to 1, b2, ..., bM} respectively
, C: b2,..., C: bM}, and divides the incident signal light from the input / output port A for each wavelength channel {a1, a2,. Output ports ｛c: a1, c: a
Output from 2, ..., c: aN} and input port {c: b}
, C: b2,..., C: bM}, and multiplex all the incident signal lights corresponding to the respective wavelength channels {b1, b2,. At the same time, they correspond to the optical wavelength multiplexing / demultiplexing unit C for removing unnecessary light existing in the wavelength region other than each wavelength channel, the input / output port B, and each wavelength channel {a1, a2,..., AN}. Input port {d: a1, d: a2, ..., d: aN} and each wavelength channel {b
Output ports {d: b corresponding to 1, b2, ..., bM} respectively
1, d: b2, ..., d: bM}, input ports {d: a1, d: a
2, ..., d: aN, the wavelength channels {a1, a
,... AN} are all multiplexed and output from the input / output port B, and the incident signal light from the input / output port B is converted into each of the wavelength channels {b1, b2,. .., b
M｝ and split each signal light into output port 出力 d: b
1, d: b2,..., D: bM}, and at the same time, an optical wavelength multiplexing / demultiplexing unit D and an optical wavelength multiplexing / demultiplexing unit that remove unnecessary light existing in a wavelength region other than each wavelength channel. C output port Ｃc:
a1, c: a2, ..., c: aN} and input ports {c: b1, c: b
, C: bM}, input ports {d: a1, d: a2,..., D: aN} and output ports {d: b1, d: of the optical wavelength multiplexing / demultiplexing unit D.
b2,..., d: bM}, respectively, are connected between the input port and the output port of the corresponding wavelength channel, and the propagation direction of each signal light is set to the output port {c: a1, c: a
2, ..., c: aN} and {d: b1, d: b2, ..., d: bM}, respectively, the corresponding input ports {d: a1, d: a2, ..., d: a
N: and optical isolators ｛i: a1, i: a2,..., I: a that restrict only to the propagation direction to c: b1, c: b2,.
N} and {i: b1, i: b2, ..., i: bM}.

As shown in FIG. 7, the isolator circuit further includes an output port {c: a1,
c: a2, ..., c: aN} and input ports {c: b1, c: b2, ...
, C: bM} and the input port {d: a of the optical wavelength multiplexing / demultiplexing unit D.
1, d: a2, ..., d: aN} and output ports {d: b1, d: b
Light intensity adjustment for changing the output signal light intensity for each wavelength channel for some or all connections between the input port and the output port of the corresponding wavelength channel with 2,..., D: bM｝ Instrument ｛k: a1, k: a2, ..., k: aN, k: b1, k: b
2, ..., k: bM｝. This light intensity adjuster is preferably an optical variable attenuator or a semiconductor optical amplifier. Preferably, the optical wavelength multiplexing / demultiplexing unit is an arrayed waveguide type optical circuit.

[Second Embodiment] FIG. 8 is a diagram showing the configuration of a first embodiment of the optical amplifier of the present invention. In this embodiment, two optical wavelength multiplexer / demultiplexers C branch from one optical waveguide to individual optical waveguides for each wavelength channel and couple from individual optical waveguides for each wavelength channel to one optical waveguide. D, an individual optical waveguide interconnecting the ports corresponding to the wavelengths of the two optical wavelength multiplexer / demultiplexers C and D which are branched for each wavelength channel, and on the individual optical waveguide There are provided an isolator means provided with the provided optical isolator, and one optical amplifying means.

The configuration shown in FIG. 8A has a wavelength channel group {a1, a2,..., Consisting of three or more wavelength channels, each channel having one of the upstream and downstream propagation directions and different wavelengths from each other. , AN, b1, b2, ..., b
Of M｝, the wavelength channel groups {a1, a2,..., AN} whose propagation directions are the same in the forward direction and the wavelength channel groups {b1, b2,. An optical isolator circuit comprising an input port and an output port, and input / output ports A and B serving as output ports and input ports, respectively.
Input / output port A, each wavelength channel # a1, a2, ..., a
Output ports {c: a1, c: a2, ... corresponding to N}
, C: aN} and each wavelength channel {b1, b2, ..., bM}
, C: b1, c: b2, ..., c:
bM}, the input signal light from the input / output port A is divided for each wavelength channel {a1, a2,..., aN}, and each signal light is divided into output ports {c: a1, c: a2, , C: aN} and input ports {c: b1, c: b2, ..., c: bM}
From each wavelength channel ｛b1, b2, ...
, BM} are multiplexed and output from an input / output port A, and at the same time, an optical wavelength multiplexing / demultiplexing unit C for removing unnecessary light existing in a wavelength region other than each wavelength channel. Port E, each wavelength channel {a1, a2, ..., aN}
Input ports ｛d: a1, d: a2, ..., d:
aN} and output ports {d: b1, d: b2,..., d: bM} corresponding to the respective wavelength channels {b1, b2,..., bM}, and input ports {d: a1,. d: a2,..., d: aN}, all the signal lights corresponding to the wavelength channels {a1, a2,. In addition, the incident signal light from the input / output port E is divided for each of the wavelength channels {b1, b2,..., BM}, and each signal light is divided into the output ports {d: b1, d: b2,. , D: bM}, and at the same time, the output ports {c: a1,... Of the optical wavelength multiplexing / demultiplexing unit D and the optical wavelength multiplexing / demultiplexing unit C that remove unnecessary light existing in wavelength regions other than the wavelength channels. , c: aN} and input ports {c: b1, c: b2,..., c: bM} and input ports {d: a1, d of the optical wavelength multiplexing / demultiplexing unit D. : a2, ..., d: aN} and output ports {d: b1, d: b2, ..., d: bM} The input port and the output port of the channel are connected to each other, and the propagation directions of the respective signal lights are determined by the output ports {c: a1, c: a2,..., C: aN} and {d: b1, d : b
2, ..., d: bM} to the corresponding input port {d: a
1, d: a2, ..., d: aN} and {c: b1, c: b2, ..., c: b
Optical isolator 制 限 i: a that restricts only to the direction of propagation to M｝
1, i: a2, ..., i: aN} and ｛i: b1, i: b2, ..., i: b
M｝, an optical isolator circuit, input / output port B, input ports {h: a1, h: a2, ..., h: aN respectively corresponding to each wavelength channel {a1, a2, ..., aN} , And output ports {h: b1, h: b2,..., H: bM} corresponding to the respective wavelength channels {b1, b2,..., BM}, and the incident signal from the input / output port B. Light is transmitted to each wavelength channel ｛b1, b
2,..., BM}, each signal light is output from the output port {h: b1, h: b2,..., H: bM}, and the input port {h: a1,. h: a2,..., h: aN}, all the incident signal lights corresponding to the respective wavelength channels {a1, a2,.
At the same time, an optical wavelength multiplexing / demultiplexing unit H for removing unnecessary light existing in a wavelength region other than each wavelength channel, an input / output port F, and an output port corresponding to each wavelength channel {a1, a2,..., AN}. Input ports {g: b1, g: b2,... Corresponding to {g: a1, g: a2,..., G: aN} and each wavelength channel {b1, b2,. , G: bM}, and respective signals corresponding to the wavelength channels {b1, b2,..., BM} incident from the input ports {g: b1, g: b2,. All the lights are multiplexed and output from the input / output port F, and the incident signal light from the input / output port F is converted into each wavelength channel {a1,
a2, ..., aN} and output each signal light from output port {g: a1, g: a2, ..., g: aN}, and simultaneously to the wavelength region other than each wavelength channel The output ports {h: a1, h: a2,..., H: aN} and the input ports {h:} of the optical wavelength multiplexing / demultiplexing section G for removing existing unnecessary light and the optical wavelength multiplexing / demultiplexing section H. b
, H: bM}, input ports {g: a1, g: a2,..., G: aN} and output ports {g: b of the optical wavelength multiplexing / demultiplexing unit G.
, G: b2,..., G: bM} are connected between the input port and the output port of the corresponding wavelength channel, and the propagation direction of each signal light is set to the output port {g: a1,
g: a2, ..., g: aN} and {h: b1, h: b2, ..., h: bM} and the corresponding input ports {h: a1, h: a2, ..., h respectively :
aN｝ and {g: b1, g: b2, ..., g: bM} optical isolators の み j: a1, j: a2, ..., j: a
An optical isolator circuit comprising N1 and {j: b1, j: b2,..., J: bM}, and between input / output ports E and F;
An optical amplifier is provided for amplifying output signal light from the input / output ports E and F and outputting the amplified signal light to the input / output ports E and F, respectively.

The configuration shown in FIG. 8B has a configuration in which the optical isolator circuit on one side of the optical amplifier is omitted from the configuration example shown in FIG. 8A. Even with such a configuration, isolation in the signal light propagation direction can be ensured.

[Third Embodiment] FIG. 9 is a diagram showing a configuration of an optical amplifier according to a third embodiment of the present invention. In the configuration example of FIG. 9A, an optical wavelength multiplexer / demultiplexer C that optically branches a single optical waveguide and an individual optical waveguide for each wavelength channel, all the wavelength channels are divided without overlapping. For each of the number of subgroups smaller than the number of wavelength channels, the number of optical wavelength multiplexer / demultiplexers D-1 and D- equal to the number of subgroups for multiplexing / branching all wavelength channels belonging to each subgroup.
, D-n, optical wavelength multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer D-
1, D-2,..., D-n, the optical waveguides interconnecting the corresponding wavelength channel ports on the side branched to each wavelength channel, and the individual branched optical waveguides. It comprises two optical isolator means provided with optical isolators arranged, and n optical amplifying means connecting the D side of each optical isolator means to D, G and E and F in the figure. .

This configuration example is an example in which the wavelength channel subgroup is composed only of wavelength channels having the same propagation direction. Since the isolation in the propagation direction can be ensured for each wavelength channel, it is assumed that each Even if a wavelength channel whose propagation direction is reverse exists in the wavelength channel group, optical amplification of signal light can be performed without any problem. The configuration example in FIG. 9B is a simple optical waveguide multiplexer / demultiplexer in which the number of wavelength channels belonging to one of the wavelength channel subgroups in the configuration example in FIG. 9A is one. It is replaced by a wave path.

[Fourth Embodiment] FIG. 10 is a diagram showing the configuration of an optical amplifier according to a fourth embodiment of the present invention. In the configuration example of FIG. 10A, an optical wavelength multiplexer / demultiplexer C that optically branches a single optical waveguide and an individual optical waveguide for each wavelength channel, and all wavelength channels are divided without overlapping. For each of the number of subgroups smaller than the number of wavelength channels, the number of optical wavelength multiplexer / demultiplexers D-1 and D- equal to the number of subgroups for multiplexing / branching all wavelength channels belonging to each subgroup.
, D-n, optical wavelength multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer D-
1, D-2,..., D-n, the optical waveguides interconnecting the corresponding wavelength channel ports on the side branched to each wavelength channel, and the optical wavelength Two optical isolator means including optical isolators arranged in optical waveguides corresponding to a part of the demultiplexers D-1, D-2,..., D-n; On the D side, there are provided n optical amplifiers for interconnecting Di having an optical isolator and Dj not having an optical isolator.

In this configuration example, the wavelength channel subgroup is composed of only the wavelength channels having the same propagation direction, and the optical isolator is arranged only on one of the front and rear sides of the optical amplifying unit, so that the signal light is transmitted. This is an example of a configuration for ensuring isolation in the propagation direction. Also in this example, since the isolation in the propagation direction can be ensured for each wavelength channel, even if there is a wavelength channel whose propagation direction is reverse in each wavelength channel group, there is no problem in optical amplification of the signal light. It can be performed. FIG.
In the configuration example of FIG. 10B, the optical wavelength multiplexer / demultiplexer of the subgroup in which the number of the wavelength channels belonging to the subgroup is one of the wavelength channel subgroups in the configuration example of FIG. 10A is a simple optical waveguide. It has been replaced.

[Fifth Embodiment] A fourth embodiment of the optical amplifier according to the present invention comprises an optical wavelength multiplexer / demultiplexer C for optically branching one optical waveguide and an individual optical waveguide for each wavelength channel. For each sub-group of the number of wavelength channels smaller than the number of wavelength channels obtained by dividing the upstream wavelength channel group without overlapping the wavelength channels, the number of sub-groups equal to the number of sub-groups for branching all wavelength channels belonging to each sub-group is determined. Each of the optical wavelength multiplexer / demultiplexers D-1, D-2,..., D-m, and the number of sub-groups smaller than the number of wavelength channels obtained by dividing the group of downstream wavelength channels without overlapping the wavelength channels, The number of optical wavelength multiplexer / demultiplexers D-m + 1, D-m + 2,..., D-n, the number of which is equal to the number of subgroups that multiplex and divide all wavelength channels belonging to each subgroup. Multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer D-1 D-2,..., D-m, an optical waveguide for interconnecting ports corresponding to the wavelengths for the upstream wavelength channel on the side branched to each wavelength channel, and an optical wavelength multiplexer / demultiplexer C; Optical wavelength multiplexer / demultiplexer D-m + 1, D-m
+2,..., D-n The number of optical waveguides and the number of light beams equal to the number of subgroups, which interconnect the ports corresponding to the wavelengths for the downstream wavelength channel on the side branched to each wavelength channel. Isolator i: EK-1, i: EK-2, ...,
i: EK-m, i: EK-m + 1, i: EK-m + 2, ..., i: E-
K-n, so as to limit the propagation direction of the signal light to the upstream direction,
The input / output ports and optical isolators i: EK-1, i: E on the side where all the upstream wavelength channels of the optical wavelength multiplexer / demultiplexers D-1, D-2,... −K−2,..., I: an optical waveguide connecting to the E−K−m, and an optical wavelength multiplexer / demultiplexer D−m + 1, D− so as to restrict the propagation direction of the signal light in the downward direction. -m + 2, ..., D
-n and the input / output port on the side to which all downstream wavelength channels of -n are coupled, i: EK-m + 1, i: EK-m +
2,..., I: an optical amplifier is provided between the respective optical isolators of the two optical isolator means having an optical waveguide for connecting to the E-K-n via the optical waveguide.

In the embodiment shown in FIG. 11, m = 1 and n =
1, the optical wavelength multiplexer / demultiplexer C for optically coupling / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, and the optical wavelength multiplexer / demultiplexer for coupling / branching a group of upstream wavelength channels. D-1, optical wavelength multiplexer / demultiplexer D-2 capable of multiplexing / dividing a group of downstream wavelength channels, optical wavelength multiplexer / demultiplexers C and D-1
An optical waveguide interconnecting the ports corresponding to the wavelengths of the upstream wavelength channel on the branching side for each wavelength channel, and branching for each wavelength channel of the optical wavelength multiplexer / demultiplexer C and D-2 Each optical wavelength multiplexer / demultiplexer D-1 of two optical branching / coupling circuits including optical waveguides interconnecting corresponding ports of wavelengths for the downstream wavelength channel on the side of the optical fiber.
, And between the respective optical wavelength multiplexer / demultiplexers D-2, an optical amplifier is connected via an optical waveguide, and the upstream between the optical amplifier and the optical wavelength multiplexer / demultiplexers D-1 on both sides. The optical isolator in the direction is inserted, and the optical isolator in the down direction is inserted between the optical amplifier and the optical wavelength multiplexer / demultiplexer D-2 on both sides.

The configuration shown in FIG. 11A has a wavelength channel group {a1, a2,..., Consisting of three or more wavelength channels, each channel having one of the upstream and downstream propagation directions and different wavelengths from each other. , AN, b1, b2, ...,
Of the bM}, the wavelength channel groups {a1, a2,..., aN} whose propagation directions are the same in the forward direction and the wavelength channel groups {b1, b2,. An optical amplifier comprising two optical isolator circuits, each having an input port and an output port and input / output ports A and B serving as output ports and input ports, respectively, wherein the input / output ports A, B The output ports {c: a1, c: a2,..., C: aN} corresponding to the respective wavelength channels {a1, a2,..., AN} and the respective wavelength channels {b1, b2,. , c: bM} corresponding to each of the wavelength channels {a1, a2,...,. a
N｝ and split each signal light into output port ｛c: a
1, c: a2,..., C: aN}, and each wavelength channel {b1, b2} that enters from an input port {c: b1, c: b2,. ,..., BM｝, an optical wavelength multiplexing / demultiplexing unit that multiplexes all of the incident signal lights and outputs the multiplexed signal light from the input / output port A, and simultaneously removes unnecessary light existing in a wavelength region other than each wavelength channel. C, an output port E-1, and input ports {d: a1, d: a2,..., D: aN} corresponding to the respective wavelength channels {a1, a2,..., AN}. All the signal lights corresponding to the wavelength channels {a1, a2,..., AN} incident from {d: a1, d: a2,..., D: aN} are multiplexed and output port E -1 and simultaneously removes unnecessary light existing in a wavelength region other than each wavelength channel, an optical wavelength multiplexing / demultiplexing unit D-1, an input port E-2, and each wavelength channel # b1, b2, ... , BM｝ output ports respectively d: b1, d: b2,..., d: bM} and input port E
-2, the incident signal light from each wavelength channel ｛b1, b2, ...
, BM}, and outputs each signal light from the output ports {d: b1, d: b2,..., D: bM}, and at the same time, unnecessary light existing in a wavelength region other than each wavelength channel. An optical isolator i which is connected to the output port E-1 and limits the propagation direction of the signal light to only the propagation direction from the output port E-1 to the input port F-1. : EK and an optical isolator i: KE that is connected to the input port E-2 and restricts the propagation direction of the signal light to only the propagation direction from the output port F-2 to the input port E-2. Optical isolator circuit, input / output port B, each wavelength channel # a1, a
The input ports {h: a1,
h: a2, ..., h: aN} and each wavelength channel {b1, b
Output ports {h: b1,
h: b2,..., h: bM}, and divides the incident signal light from the input / output port B for each wavelength channel {b1, b2,. Port ｛h: b1, h: b
2, ..., output from h: bM} and input port {h: a
1, h: a2,..., H: aN}, multiplex all the incident signal lights corresponding to each wavelength channel {a1, a2,. At the same time, the optical wavelength multiplexing / demultiplexing unit H for removing unnecessary light existing in the wavelength region other than each wavelength channel, the input port F-1, and the wavelength channels {a1, a2,..., AN} are respectively supported. , G: aN} and input signal light from the input port F-1 to each of the wavelength channels {a1, a2,.
N｝ and split each signal light into output port 出力 g: a
1, g: a2,..., G: aN}, and an optical wavelength multiplexing / demultiplexing unit G-1 for simultaneously removing unnecessary light existing in a wavelength region other than each wavelength channel, and an output port F-2. And input ports {g: b1, g: b2,..., G: bM} respectively corresponding to the wavelength channels {b1, b2,..., BM}, and input ports {g: b
1, g: b2,..., G: bM}, all the signal lights corresponding to the wavelength channels {b1, b2,. An optical isolator circuit having an optical wavelength multiplexing / demultiplexing unit G-2 for outputting and simultaneously removing unnecessary light existing in a wavelength region other than each wavelength channel, which is connected to an input port F-1 and a signal light propagation direction. Output port E
-1 which is connected to an output port F-2 and an optical isolator i: K-F for limiting only the direction of propagation from the output port F-1 to the input port F-1. Optical isolator i: F that restricts only to the direction of propagation to 2
-K optical isolator circuit, optical isolator i: E
-K and an optical isolator i: K-F, an optical amplifier K-1 for amplifying an output signal light from the output port E-1 and outputting the amplified signal light to the input port F-1, and an optical isolator i: An optical amplifier K-2 between the FK and the optical isolator i: KE for amplifying the output signal light from the output port F-2 and outputting the amplified signal light to the input port E-2; I have.

In this configuration example, since the wavelength channels grouped according to the propagation direction of the signal light are subjected to optical amplification after being wavelength-multiplexed again, the isolator for ensuring the isolation in the propagation direction. Need not be arranged on individual optical waveguides branched for each wavelength channel, and can be arranged in a form shared by each wavelength channel on an optical waveguide in which wavelength channels in the same propagation direction are multiplexed. The circuit configuration can be simplified.
The configuration example of FIG. 11B is a simple optical waveguide multiplexer / demultiplexer in which the number of wavelength channels belonging to one of the wavelength channel subgroups in the configuration example of FIG. 11A is one. It is replaced by a wave path.

[Sixth Embodiment] FIGS. 12 (a) and 12 (b), which are the fifth embodiment of the optical amplifier according to the present invention, are similar to those shown in FIGS.
In the configuration examples (a) and (b), the optical isolators are arranged only on one side before and after the optical amplifying unit to ensure isolation in the signal light propagation direction. Wavelength multiplexer / demultiplexer C for optically coupling / branching between two optical waveguides and individual optical waveguides for each wavelength channel, optical wavelength multiplexer / demultiplexer D-1 for coupling / branching a group of upstream wavelength channels, downstream wavelength channel Wavelength multiplexer / demultiplexer D-2, and optical wavelength multiplexer / demultiplexer C and D-1
An optical waveguide interconnecting the ports corresponding to the wavelengths of the upstream wavelength channel on the side branched for each wavelength channel, and branching for each wavelength channel of the optical wavelength multiplexer / demultiplexer C and D-2. Between two optical wavelength multiplexer / demultiplexers D-1 and two optical wavelength multiplexers / demultiplexers of two optical branching / coupling circuits each having an optical waveguide for interconnecting the corresponding port of the wavelength for the downstream wavelength channel on the transmitting side. An optical amplifier is connected between the optical amplifiers D-2 via an optical waveguide, and an upward optical isolator is inserted between the optical amplifier and the optical wavelength multiplexer / demultiplexer D-1 on one side,
A down optical isolator is inserted between the optical amplifying unit and one optical wavelength multiplexer / demultiplexer D-2.

Seventh Embodiment FIG. 13 is a diagram showing the configuration of a sixth embodiment of the optical amplifier according to the present invention. In the configuration example of FIG. 13A, an optical wavelength multiplexer / demultiplexer C that optically branches a single optical waveguide and an individual optical waveguide for each wavelength channel, and a group of upstream wavelength channels overlaps the wavelength channels. The number of optical wavelength multiplexer / demultiplexers D-1 and D equal to the number of subgroups for multiplexing / branching all the wavelength channels belonging to each subgroup for each subgroup smaller than the number of wavelength channels divided without division. -2,..., D-m, for each subgroup less than the number of wavelength channels obtained by dividing the downstream wavelength channel group without overlapping the wavelength channels, all the wavelength channels belonging to each subgroup are assigned. Optical wavelength multiplexer / demultiplexers D-m + 1, D-m + 2,..., D-n, optical wavelength multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer having the same number of sub-groups , D-2,..., D-m An optical waveguide interconnecting ports corresponding to the wavelengths of the upstream wavelength channels on the side branched to the channel, an optical wavelength multiplexer / demultiplexer C, and optical wavelength multiplexer / demultiplexers D-m + 1, D-m
+2,..., D-n The number of optical waveguides and the number of light beams equal to the number of subgroups, which interconnect the ports corresponding to the wavelengths for the downstream wavelength channel on the side branched to each wavelength channel. Isolator i: EK-1, i: EK-2, ...,
i: EK-m, i: EK-m + 1, i: EK-m + 2, ..., i: E-
K-n, so as to limit the propagation direction of the signal light to the upstream direction,
The input / output ports and optical isolators i: EK-1, i: E on the side where all the upstream wavelength channels of the optical wavelength multiplexer / demultiplexers D-1, D-2,... −K−2,..., I: an optical waveguide connecting to the E−K−m, and an optical wavelength multiplexer / demultiplexer D−m + 1, D− so as to restrict the propagation direction of the signal light in the downward direction. -m + 2, ..., D
-n and the input / output port on the side to which all downstream wavelength channels of -n are coupled, i: EK-m + 1, i: EK-m +
2, ..., i: an optical isolator means having an optical waveguide connecting the E-K-n, an optical wavelength combiner for optically coupling and branching between one optical waveguide and an individual optical waveguide for each wavelength channel. The demultiplexer C has a number of subgroups equal to the number of subgroups that divide and branch all the wavelength channels belonging to each subgroup for each subgroup of a number smaller than the number of wavelength channels obtained by dividing all the wavelength channels without overlapping. Optical wavelength multiplexer / demultiplexer D
-1, D-2, ..., D-m, D-m + 1, D-m + 2, ..., D-n Optical wavelength multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer D- 1, D-2, ...,
An optical waveguide interconnecting a corresponding wavelength channel port on the side branched to each wavelength channel with each of D-n, and an optical isolator means including an optical isolator disposed in each of the branched individual optical waveguides , And optical amplifying means for connecting both optical isolator means to each other.

In this configuration example, the wavelength channels grouped according to the propagation direction of the signal light are subjected to optical amplification after being wavelength-multiplexed again, and are used to ensure isolation in the propagation direction. The isolator is disposed on each of the optical waveguides branched for each wavelength channel, and the isolator is disposed on the optical waveguide on which wavelength channels in the same propagation direction are multiplexed, in a form shared by each wavelength channel. Are mixed. FIG.
In the configuration example of FIG. 13B, the optical wavelength multiplexer / demultiplexer in the subgroup of the wavelength channel subgroup of the configuration example of FIG. It has been replaced.

[Eighth Embodiment] FIG. 14 is a diagram showing the configuration of an optical amplifier according to a seventh embodiment of the present invention. In the configuration example of FIG. 14A, an optical wavelength multiplexer / demultiplexer C that optically branches a single optical waveguide and an individual optical waveguide for each wavelength channel, and a group of upstream wavelength channels is defined as a wavelength channel. For each of the number of subgroups smaller than the number of wavelength channels divided without overlapping, the number of optical wavelength multiplexer / demultiplexers D-1, D equal to the number of subgroups for multiplexing / branching all wavelength channels belonging to each subgroup. D-2,..., D-m, all wavelength channels belonging to each sub-group, for each sub-group less than the number of wavelength channels obtained by dividing the downstream wavelength channel group without overlapping the wavelength channels. , D-m + 2,..., D-n, the optical wavelength multiplexer / demultiplexer C and the optical wavelength multiplexer / demultiplexer, the number of which is equal to the number of sub-groups Waves D-1, D-2, ..., D-m
An optical waveguide, an optical wavelength multiplexer / demultiplexer C, and an optical wavelength multiplexer / demultiplexer D-m for mutually connecting ports corresponding to the wavelengths for the upstream wavelength channel on the side branched to each wavelength channel;
+1, D-m + 2,..., D-n, the optical waveguides and the subgroups of the sub-groups, which interconnect the ports corresponding to the wavelengths for the downstream wavelength channel on the side branched to each wavelength channel. Less than the number of optical isolators i: EK-1, i: E-
K-2, ..., i: EK-p, i: EK-p + 1, i: EK-p +
, I: EK-s, the optical wavelength multiplexer / demultiplexers D-1, D-2,..., D-m so as to limit the propagation direction of the signal light to the upstream direction.
, D-2,..., And Dp, the input / output port and the optical isolator i: EK-1, i: E- K-2,..., I: an optical waveguide connecting to the EKp, and an optical wavelength multiplexer / demultiplexer D-m + 1, D- so as to restrict the propagation direction of the signal light in the downward direction. m + 2, ..., D-n
, D-p + 1, D-p + 2,..., D-s, the input / output port and the optical isolator i: EK-p + 1, i: EK-p + 2, ..., i: EK
optical isolator means comprising an optical waveguide connecting to -s
An optical wavelength multiplexer / demultiplexer C for optically multiplexing / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, for each subgroup smaller than the number of wavelength channels obtained by dividing all wavelength channels without overlapping. , The number of optical wavelength multiplexer / demultiplexers D-1, D-2,..., Which is equal to the number of subgroups for multiplexing / branching all the wavelength channels belonging to each subgroup.
D-m, D-m + 1, D-m + 2,..., D-n, optical wavelength multiplexer / demultiplexer C
And optical wavelength multiplexer / demultiplexers D-1, D-2,..., D-n. Of the individual optical waveguides obtained, the optical wavelength multiplexer / demultiplexer D-
1, D-2,..., D-p, D-p + 1, D-p + 2,..., D-s And an optical amplifying means for connecting the two optical isolator means to each other.

In this configuration example, the optical isolators arranged on both sides of the optical amplifier in the seventh embodiment are arranged on only one side. Even with such a configuration, the optical amplifier functions sufficiently.

[Ninth Embodiment] FIG. 15 is a diagram showing the configuration of an optical amplifier according to an eighth embodiment of the present invention. In this example,
Between the two optical wavelength multiplexing / demultiplexing units of the optical isolator means in the above embodiment, an optical variable intensity adjuster ｛v: a1, v: a2, ...
, v: aN, v: b1, v: b2,..., v: bM}, and has a function of arbitrarily adjusting the signal light intensity of each wavelength channel.

In the above embodiment of the optical amplifier of the present invention, at least one optical amplifying unit, an optical isolator for restricting the propagation direction of each wavelength channel, and signal light of a plurality of wavelength channels are combined. A wave multiplexing / demultiplexing unit is provided.

When an erbium-doped optical fiber pumped by a semiconductor laser (FIGS. 2A, 2B, and 2C) is used as the optical amplifier, for example, the amplification wavelength band of the optical amplifier is zero dispersion wavelength range of the dispersion shift fiber. And a band of about 1.53 × 10 ⁻⁶ m to 1.56 × 10 ⁻⁶ m including the array waveguide type optical multiplexer / demultiplexer as an optical multiplexer / demultiplexer. If the two optical multiplexing / demultiplexing units and the isolator for each wavelength channel are created as the same plane-based circuit, the optical loss per optical multiplexing / demultiplexing unit is ideally 2.
1 dB (see K. Okamoto et al., OFC'97 ThB.1), the optical loss per optical isolator is approximately 0.5 dB, and the loss per optical fiber connection is approximately 0.25 dB. When the input signal strength is -20 dBm, the optical amplification gain of the optical amplification unit is approximately 30 dB (Funabashi, etc.
According to the 1995 Autumn Society of IEICE Transactions C-216), the net optical gain of the optical amplifier is estimated to be 30−2.1 × 4−0.5 × 2−0.25 × 4 = 30-10.4 = 19.6dB. Loss of each section in an optical transmission system with a relay interval of 80 km and an average optical fiber loss of 0.23 dB / km 1
It can be seen that 8.4 dB can be compensated.

The crosstalk of the arrayed waveguide type optical multiplexer / demultiplexer is approximately -25 dB for a normal type and approximately -40 dB for a case where crosstalk is reduced by using a phase compensator (Yamada et al., Autumn 1997 It is estimated that the isolation of the optical isolator is about 4
If it is estimated to be 0 dB, oscillation in an arbitrary wavelength channel is suppressed in the same manner as a normal optical amplifier, and two Fresnel reflection (-14 dB) points existing near the front and rear outside the optical amplifier and an arbitrary point having a different propagation direction. Assuming an optical resonator composed of two wavelength channels in a loop, (gain of the optical amplifier per round trip of the resonator) − (optical loss per round trip of the resonator) is 30 × 2− ｛14 + 25 [ 40] × 2｝ × 2 = −68 [−128] dB, and the loss inside the resonator is so large that a net gain cannot be obtained. Therefore, even in such a worst case, the oscillation of the optical amplifier of the present invention can be suppressed.

It is estimated that the ASE emitted from the optical amplifier can be suppressed to a level of −25 [−40] × 2 = −50 [−80] dB from the amount of crosstalk of the arrayed waveguide type optical circuit. Further, assuming unnecessary signal light that propagates in the direction opposite to the transmission direction in an arbitrary wavelength channel and undergoes optical amplification using signal light of another channel as pump light due to a nonlinear optical process or the like on a transmission line, the optical amplifier of the present invention Is expected to have an effect of reducing 30−2.1 × 4−40 × 2−0.25 × 4 = −59.4 dB against unnecessary signal light. Since this value is sufficiently larger than the gain given to the unnecessary signal light by the above-described nonlinear optical process, such unnecessary signal light can be effectively removed.

[0036]

As described above, according to the present invention,
Before and after the optical amplifying unit, the signal light is once demultiplexed by the arrayed waveguide type optical multiplexer / demultiplexer, and subsequently multiplexed again after passing through the optical isolator that limits the propagation direction for each channel, or once. Since the signal light is demultiplexed and subsequently combined again after passing through the optical isolator, the optical circuit is guided to the output of the optical amplifier or the optical amplifier. And the optical signals propagating in both directions are collectively optically amplified, and at the same time, an optical signal generated in a wavelength region other than each wavelength channel can be removed. Furthermore, by arranging an optical variable intensity adjuster for each wavelength channel in a circuit section that separates the signal light before and after the optical amplifier for each wavelength channel, the intensity of the signal light for each channel can be individually set. The effect that can be adjusted is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a configuration of a conventional optical amplifier.

FIG. 2 is a diagram for explaining a configuration of an optical amplifier of a conventional optical amplifier.

FIG. 3 is a diagram illustrating a configuration of a conventional bidirectional optical amplifier.

FIG. 4 is a diagram illustrating a configuration of another conventional bidirectional optical amplifier.

FIG. 5 is a diagram illustrating a configuration of an arrayed waveguide type optical multiplexer / demultiplexer.

FIG. 6 is a diagram showing an embodiment of the optical isolator circuit of the present invention.

FIG. 7 is a diagram showing another embodiment of the optical isolator circuit of the present invention.

FIG. 8 is a diagram showing an embodiment of the optical amplifier of the present invention.

FIG. 9 is a diagram showing another embodiment of the optical amplifier of the present invention.

FIG. 10 is a diagram showing another embodiment of the optical amplifier of the present invention.

FIG. 11 is a diagram showing another embodiment of the optical amplifier of the present invention.

FIG. 12 is a diagram showing another embodiment of the optical amplifier of the present invention.

FIG. 13 is a diagram showing another embodiment of the optical amplifier of the present invention.

FIG. 14 is a diagram showing another embodiment of the optical amplifier of the present invention.

FIG. 15 is a diagram showing another embodiment of the optical amplifier of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 optical amplifier 2 optical amplifier 3, 6 optical isolator 4 rare earth doped optical fiber 5 excitation light source 7 optical coupler 8 semiconductor optical amplifier 9 photodetector 10 leakage light ASE intensity comparison monitoring device 11 laser driver 12 excitation laser 13 Excitation light reflection mirror 14 Wavelength multiplexing optical multiplexer / demultiplexer 15 Planar waveguide substrate 16 Optical input / output waveguide unit 17 Slab waveguide unit 18 Arrayed waveguide grating unit A, B, E, F Signal light input / output ports C, D , G, H optical wavelength multiplexing / demultiplexing unit c: b, d: a, g: b, h: a signal light input port c: a, d: b, g: a, h: b signal light output port i, j Optical isolator v Optical variable intensity adjuster

Claims (22)

[Claims] 1. Each channel has an arbitrary upstream or downstream propagation direction and has different wavelengths from each other.
Among the wavelength channel groups {a1, a2,..., AN, b1, b2,..., BM} composed of the above wavelength channels, the wavelength channel groups {a1,.
A and B are input ports, output ports, output ports and output ports for the same wavelength channel group {b1, b2,..., bM}, respectively, with a2,. An optical isolator circuit having input / output ports A and B serving as input ports, wherein the input / output port A and each wavelength channel # a1, a2, ..., a
Output ports {c: a1, c: a2, ... corresponding to N}
, C: aN} and each wavelength channel {b1, b2, ..., bM}
, C: b1, c: b2, ..., c:
bM}, the input signal light from the input / output port A is divided for each wavelength channel {a1, a2,..., aN}, and each signal light is divided into output ports {c: a1, c: a2, , C: aN} and input ports {c: b1, c: b2, ..., c: bM}
From each wavelength channel ｛b1, b2, ...
, BM} are multiplexed and output from an input / output port A, and at the same time, an optical wavelength multiplexing / demultiplexing unit C for removing unnecessary light existing in a wavelength region other than each wavelength channel. Port B, each wavelength channel {a1, a2, ..., a
Input ports {d: a1, d: a2, ... respectively corresponding to N}
, D: aN} and each wavelength channel {b1, b2, ..., bM}
Output ports ｛d: b1, d: b2, ..., d:
bM}, and all the signal lights corresponding to the wavelength channels {a1, a2,..., aN} incident from the input ports {d: a1, d: a2,. Combine and input / output port B
, And splits the incident signal light from the input / output port B for each wavelength channel {b1, b2,..., BM} and divides each signal light into the output ports {d: b1, d: b2. , ..., d: b
The output ports {c: a1, c: a2 of the optical wavelength multiplexing / demultiplexing section D and the optical wavelength multiplexing / demultiplexing section C, which output from M｝ and simultaneously remove unnecessary light existing in wavelength regions other than the wavelength channels. , ..., c:
aN} and input ports {c: b1, c: b2,..., c: bM} and input ports {d: a1, d: a2,.
N} and output ports {d: b1, d: b2, ..., d: bM}
Connect between the input port and output port of each corresponding wavelength channel, and set the propagation direction of each signal light,
The output ports {c: a1, c: a2, ..., c: aN} and {d: b
, D: b2, ..., d: bM} and corresponding input ports {d: a1, d: a2, ..., d: aN} and {c: b1, c: b2, ...
, I: a1, i: a2,..., I: aN} and {i: b1, i: b2,.
, I: bM｝. 2. The output ports {c: a1, c: a2,..., C: aN} and the input ports {c: b1,.
, c: bM}, input ports {d: a1, d: a2,..., d: aN} and output ports {d: b of the optical wavelength multiplexing / demultiplexing unit D.
Change the output signal light intensity for each wavelength channel for some or all connections between the input port and output port of the corresponding wavelength channel with 1, d: b2, ..., d: bM｝ Light intensity adjuster ｛k: a1, k: a2, ..., k: aN, k: b1, k:
2. The optical isolator circuit according to claim 1, comprising: b2,..., k: bM}. 3. The optical isolator circuit according to claim 1, wherein the optical wavelength multiplexing / demultiplexing unit is an arrayed waveguide type optical circuit. 4. The optical isolator circuit according to claim 2, wherein said optical intensity adjuster is an optical variable attenuator or a semiconductor optical amplifier. 5. A signal light having a number smaller than the number of wavelength channels for signal light propagating through a plurality of wavelength channels of three or more channels in which an upward or downward propagation direction is set for each wavelength channel in the same optical fiber core. An optical amplifier comprising: an optical amplifying means; and an optical isolator means for performing branching and coupling of signal light of each wavelength channel and isolation in a propagation direction before, after or before or after the optical amplifying means. 6. An optical multiplexing / branching circuit for branching from one optical waveguide into individual optical waveguides for each wavelength channel, an optical isolator disposed in the branched individual optical waveguides, and the individual optical waveguides as one optical waveguide. 6. The optical amplifier according to claim 5, further comprising: an optical isolator having an optical coupling / branching circuit coupled to the optical amplifier; and a single optical amplifying means for amplifying all the coupled signal lights. 7. An optical multiplexing / branching circuit for branching from one optical waveguide into individual optical waveguides for each wavelength channel, an optical isolator disposed in the branched individual optical waveguides, and a plurality of optical waveguides. 6. The light according to claim 5, further comprising: an optical isolator having a plurality of optical coupling / branching circuits coupled to the optical waveguide; and a plurality of optical amplifying means for amplifying signal light for each of the plurality of optical waveguides. amplifier. 8. An optical multiplexing / branching circuit for branching from one optical waveguide into individual optical waveguides for each wavelength channel, an optical isolator disposed in the branched individual optical waveguides, and two wavelength channels in forward and reverse directions. The optical isolator means comprising an optical multiplexing / branching circuit coupled to one optical waveguide for each, and two optical amplifying means for amplifying signal light for each of the two optical waveguides. 8. The optical amplifier according to 7. 9. An optical multiplexing / branching circuit for branching from one optical waveguide to individual optical waveguides for each wavelength channel, and dividing each individual branched optical waveguide for each arbitrary wavelength channel group irrespective of the upward and downward propagation directions. Optical isolator means including a plurality of optical multiplexing / branching circuits respectively coupled to a number of optical waveguides equal to or less than the number of wavelength channels and optical isolators arranged in the coupled plurality of optical waveguides, and signal light for each of the plurality of optical waveguides 6. The optical amplifier according to claim 5, comprising a plurality of optical amplifiers for amplifying the optical amplifier. 10. An optical multiplexing / branching circuit for branching one optical waveguide into individual optical waveguides for each wavelength channel, and splitting the individual optical waveguides into one optical waveguide for each of two forward and backward wavelength channels. An optical isolator comprising an optical coupling / branching circuit coupled to the optical waveguide and optical isolators disposed on the two coupled optical waveguides, and two optical amplifiers for amplifying signal light for each of the two optical waveguides. The optical amplifier according to claim 9, wherein: 11. An optical multiplexing / branching circuit for branching from one optical waveguide to individual optical waveguides for each wavelength channel, an optical isolator disposed in each of the branched individual optical waveguides, and each of the individual branched optical waveguides being the same. Optical isolator means comprising a plurality of optical coupling / branching circuits respectively coupled to the number of optical waveguides equal to or less than the number of wavelength channels for each wavelength channel group in the direction, and a plurality of optical amplifiers for amplifying signal light for each of the plurality of optical waveguides 8. The method according to claim 7, further comprising:
An optical amplifier according to claim 1. 12. An optical wavelength multiplexer / demultiplexer C that branches from one optical waveguide into individual optical waveguides for each wavelength channel and couples from the individual optical waveguides for each wavelength channel to one optical waveguide. D, an individual optical waveguide interconnecting the ports corresponding to the wavelengths of the two optical wavelength multiplexer / demultiplexers C and D which are branched for each wavelength channel, and on the individual optical waveguide 7. The optical amplifier according to claim 6, further comprising: an isolator provided with the provided optical isolator; and one optical amplifier. 13. A group of wavelength channels # a1, a2,..., AN, b1, and b2 each having three or more wavelength channels, each channel having one of the upstream and downstream propagation directions and different wavelengths from each other. ,..., BM}, the wavelength channel groups {a1, a} having the same propagation direction in the forward direction
, AN} and the same wavelength channel group {b1, b2,..., BM} in which the propagation directions are opposite to each other, A and B are input and output ports and output ports and An optical amplifier comprising two optical isolator circuits having input / output ports A and B serving as input ports, wherein the input / output port A and each wavelength channel # a1, a2, ..., a
Output ports {c: a1, c: a2, ... corresponding to N}
, C: aN} and each wavelength channel {b1, b2, ..., bM}
, C: b1, c: b2, ..., c:
bM}, the input signal light from the input / output port A is divided for each of the wavelength channels {a1, a2,..., aN}, and each signal light is output to the output ports {c: a1, c: a2, , C: aN} and input ports {c: b1, c: b2, ..., c: bM}
From each wavelength channel ｛b1, b2, ...
, BM} are multiplexed and output from an input / output port A, and at the same time, an optical wavelength multiplexing / demultiplexing unit C for removing unnecessary light existing in a wavelength region other than each wavelength channel. Port E, each wavelength channel {a1, a2, ..., a
Input ports {d: a1, d: a2, ... respectively corresponding to N}
, D: aN} and each wavelength channel {b1, b2, ..., bM}
Output ports ｛d: b1, d: b2, ..., d:
bM}, and all the signal lights corresponding to the wavelength channels {a1, a2,..., aN} incident from the input ports {d: a1, d: a2,. Combined and input / output port E
, And splits the incident signal light from the input / output port E for each of the wavelength channels {b1, b2,..., BM} and divides each signal light into the output ports {d: b1, d: b2}. , ..., d: b
The output ports {c: a1, c: a2 of the optical wavelength multiplexing / demultiplexing section D and the optical wavelength multiplexing / demultiplexing section C, which output from M｝ and simultaneously remove unnecessary light existing in wavelength regions other than the wavelength channels. , ..., c:
aN} and input ports {c: b1, c: b2,..., c: bM} and input ports {d: a1, d: a2,.
N} and output ports {d: b1, d: b2, ..., d: bM}
Connect between the input port and output port of each corresponding wavelength channel, and set the propagation direction of each signal light,
The output ports {c: a1, c: a2, ..., c: aN} and {d: b
, D: b2, ..., d: bM} and corresponding input ports {d: a1, d: a2, ..., d: aN} and {c: b1, c: b2, ...
, I: a1, i: a2,..., I: aN} and {i: b1, i: b2,.
, I: bM}, I / O port B, each wavelength channel {a1, a2,.
Input ports {h: a1, h: a2, ...
, H: aN} and each wavelength channel {b1, b2, ..., bM}
Output ports ｛h: b1, h: b2, ..., h:
bM}, the input signal light from the input / output port B is divided for each wavelength channel {b1, b2,..., bM}, and each signal light is output to the output ports {h: b1, h: b2, ..., h: bM} and input ports {h: a1, h: a2, ..., h: aN}
Each wavelength channel ｛a1, a2, ...
, AN}, and multiplexes them, and outputs the multiplexed signals from the input / output port B. At the same time, the optical wavelength multiplexing / demultiplexing unit H removes unnecessary light existing in wavelength regions other than the wavelength channels. Port F, each wavelength channel {a1, a2, ..., a
Output ports {g: a1, g: a2, ... corresponding to N}
, G: aN} and each wavelength channel {b1, b2, ..., bM}
, G: b1, g: b2, ..., g:
bM}, and all the signal lights corresponding to the wavelength channels {b1, b2,..., bM} incident from the input ports {g: b1, g: b2,. Combine and input / output port F
, And the input signal light from the input / output port F is divided for each of the wavelength channels {a1, a2,..., AN}, and each signal light is output to the output ports {g: a1, g: a2}. , ..., g: a
N} and output ports {h: a1, h: a2 of the optical wavelength multiplexing / demultiplexing unit H and the optical wavelength multiplexing / demultiplexing unit H for simultaneously removing unnecessary light existing in wavelength regions other than the wavelength channels. , ..., h:
aN} and input ports {h: b1, h: b2,..., h: bM} and input ports {g: a1, g: a2,.
N} and output ports {g: b1, g: b2, ..., g: bM}
Connect between the input port and output port of each corresponding wavelength channel, and set the propagation direction of each signal light,
The output ports {g: a1, g: a2, ..., g: aN} and {h: b
, H: b2, ..., h: bM} and the corresponding input ports {h: a1, h: a2, ..., h: aN} and {g: b1, g: b2, ...
, J: a1, j: a2,..., J: aN} and {j: b1, j: b2,.
, J: bM}, and between the input / output ports E and F, amplify the output signal light from the input / output ports E and F, and input / output ports E and F, respectively.
13. The optical amplifier according to claim 12, further comprising an optical amplifier that outputs the signal to the optical amplifier. 14. An optical wavelength multiplexer / demultiplexer C for optically multiplexing / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, wherein the number of wavelength channels is smaller than the number of wavelength channels obtained by dividing all wavelength channels without overlapping. For each of the number of subgroups, the number of optical wavelength multiplexer / demultiplexers D-1, D equal to the number of subgroups for multiplexing / branching all the wavelength channels belonging to each subgroup.
D-2,..., D-n, optical wavelength multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer D-1, D-2,.
Two optical waveguides, each having an optical waveguide interconnecting the corresponding wavelength channel port on the side branching to each wavelength channel with each of the D-n, and an optical isolator arranged in each individual branched optical waveguide. 10. The optical amplifier according to claim 9, further comprising: said optical isolator means, and n optical amplifying means for mutually connecting a D side of each optical isolator means. 15. An optical wavelength multiplexer / demultiplexer C for optically multiplexing / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, wherein the number of wavelength channels is smaller than the number of wavelength channels obtained by dividing all wavelength channels without overlapping. For each of the number of subgroups, the number of optical wavelength multiplexer / demultiplexers D-1, D equal to the number of subgroups for multiplexing / branching all the wavelength channels belonging to each subgroup.
D-2,..., D-n, optical wavelength multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer D-1, D-2,.
D-n, optical waveguides for interconnecting the corresponding wavelength channel ports on the side branched to each wavelength channel, and optical wavelength multiplexer / demultiplexers D-1 and D- of the optical waveguides.
2,..., Two optical isolator means including an optical isolator disposed in an optical waveguide corresponding to a part of D-n, and an optical isolator among the D sides of the two optical isolator means. 10. The optical amplifier according to claim 9, further comprising n optical amplifying means for mutually connecting D-i obtained and D-j not having an optical isolator. 16. An optical wavelength multiplexer / demultiplexer C for optically multiplexing / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, and an optical wavelength multiplexer / demultiplexer D for multiplexing / branching a group of upstream wavelength channels. -1, an optical wavelength multiplexer / demultiplexer D-2 capable of multiplexing / branching a group of downstream wavelength channels, and an optical wavelength multiplexing / demultiplexing device C and D-1 for an upstream wavelength channel that is branched for each wavelength channel. An optical waveguide interconnecting the ports corresponding to the wavelengths, and the ports corresponding to the wavelengths for the downstream wavelength channels on the branching side for each of the optical wavelength multiplexer / demultiplexers C and D-2. An optical amplifying unit via an optical waveguide between each optical wavelength multiplexer / demultiplexer D-1 and between each optical wavelength multiplexer / demultiplexer D-2 of two optical branching / coupling circuits having an optical waveguide to be connected. Is connected between the optical amplifier and the optical wavelength multiplexer / demultiplexer D-1 on both sides. Of the inserted optical isolator, an optical amplifier according to claim 9 in which the optical isolator downlink between the optical amplifying portion and both sides of the optical wavelength multiplexing and demultiplexing device D-2 is being inserted. 17. A group of wavelength channels # a1, a2,..., AN, b1, b2 each including one of three or more wavelength channels, each of which has an upward or downward propagation direction and has a different wavelength from each other. ,..., BM}, the wavelength channel groups {a1, a} having the same propagation direction in the forward direction
, AN} and the same wavelength channel group {b1, b2,..., BM} in which the propagation directions are opposite to each other, A and B are input and output ports and output ports and An optical amplifier comprising two optical isolator circuits having input / output ports A and B serving as input ports, wherein the input / output port A and each wavelength channel # a1, a2, ..., a
Output ports {c: a1, c: a2, ... corresponding to N}
, C: aN} and each wavelength channel {b1, b2, ..., bM}
, C: b1, c: b2, ..., c:
bM}, the input signal light from the input / output port A is divided for each wavelength channel {a1, a2,..., aN}, and each signal light is divided into output ports {c: a1, c: a2, , C: aN} and input ports {c: b1, c: b2, ..., c: bM}
From each wavelength channel ｛b1, b2, ...
, BM}, and multiplexes all of the incident signal lights and outputs the multiplexed signal light from the input / output port A. At the same time, the optical wavelength multiplexing / demultiplexing section C removes unnecessary light existing in the wavelength region other than each wavelength channel. E-1 and each wavelength channel {a1, a2, ...,
Input ports {d: a1, d: a2, ... respectively corresponding to aN}
, D: aN} and input ports {d: a1, d: a2, ..., d: a
The wavelength channels ｛a1, a2, ..., a incident from N｝
An optical wavelength multiplexing / demultiplexing unit D- which removes unnecessary light existing in a wavelength region other than each wavelength channel while simultaneously multiplexing all signal lights corresponding to N｝ and outputting the multiplexed light from an output port E-1.
1. Input port E-2 and each wavelength channel {b1, b2, ...,
Output ports {d: b1, d: b2, ... respectively corresponding to bM}
, D: bM}, and splits the incident signal light from the input port E-2 into each of the wavelength channels {b1, b2,..., BM} and divides each signal light into the output ports {d: b1,. d: b2, ..., d: b
The optical wavelength multiplexing / demultiplexing unit D-2, which outputs from M｝ and simultaneously removes unnecessary light existing in wavelength regions other than each wavelength channel, is connected to the output port E-1, and the propagation direction of the signal light is changed to the output port. An optical isolator i: EK that limits only the propagation direction from E-1 to the input port F-1 is connected to the input port E-2, and the propagation direction of the signal light is changed from the output port F-2 to the input port E. Optical isolator that restricts only to the propagation direction to -2
i: Optical isolator circuit with KE, I / O port B, each wavelength channel # a1, a2, ..., a
Input ports {h: a1, h: a2, ...
, H: aN} and each wavelength channel {b1, b2, ..., bM}
Output ports ｛h: b1, h: b2, ..., h:
bM}, the input signal light from the input / output port B is divided for each wavelength channel {b1, b2,..., bM}, and each signal light is output to the output ports {h: b1, h: b2, ..., h: bM} and input ports {h: a1, h: a2, ..., h: aN}
Each wavelength channel ｛a1, a2, ...
, AN}, multiplexes and outputs all of the input signal lights corresponding to the input and output ports B, and simultaneously removes unnecessary light existing in a wavelength region other than each wavelength channel. F-1 and each wavelength channel {a1, a2, ...,
Output ports {g: a1, g: a2, ... corresponding to aN} respectively
, G: aN}, and divides the incident signal light from the input port F-1 for each wavelength channel {a1, a2,..., AN} and divides each signal light into the output ports {g: a1,. g: a2, ..., g: a
N}, simultaneously removes unnecessary light existing in wavelength regions other than each wavelength channel, an optical wavelength multiplexing / demultiplexing unit G-1, an output port F-2, and each wavelength channel 1b1, b2, ... ,
Input ports {g: b1, g: b2, ... respectively corresponding to bM}
, G: bM} and input ports {g: b1, g: b2, ..., g: b
The wavelength channels ｛b1, b2, ..., b incident from M｝
An optical wavelength multiplexing / demultiplexing unit G-2 for multiplexing all the signal lights corresponding to M｝ and outputting the multiplexed light from an output port F-2 and simultaneously removing unnecessary light existing in a wavelength region other than each wavelength channel. An optical isolator i: K-F, which is connected to the input port F-1 and limits the propagation direction of the signal light to only the propagation direction from the output port E-1 to the input port F-1, and is connected to the output port F-2. And an optical isolator that limits the propagation direction of the signal light to only the propagation direction from the output port F-2 to the input port E-2.
i: an optical isolator circuit including FK, between the optical isolator i: EK and the optical isolator i: KF, and amplifying the output signal light from the output port E-1 to the input port F -1 and an optical amplifying unit K-1 which is located between the optical isolator i: FK and the optical isolator i: KE, amplifies the output signal light from the output port F-2, and 17. The optical amplifier according to claim 16, further comprising an optical amplifier K-2 for outputting the signal to E-2. 18. An optical wavelength multiplexer / demultiplexer C for optically multiplexing / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, and an optical wavelength multiplexer / demultiplexer D for multiplexing / branching a group of upstream wavelength channels. -1, an optical wavelength multiplexer / demultiplexer D-2 capable of multiplexing / branching a group of downstream wavelength channels, and an optical wavelength multiplexing / demultiplexing device C and D-1 for an upstream wavelength channel that is branched for each wavelength channel. An optical waveguide interconnecting the ports corresponding to the wavelengths, and the ports corresponding to the wavelengths for the downstream wavelength channels on the branching side for each of the optical wavelength multiplexer / demultiplexers C and D-2. An optical amplifying unit via an optical waveguide between each optical wavelength multiplexer / demultiplexer D-1 and between each optical wavelength multiplexer / demultiplexer D-2 of two optical branching / coupling circuits having an optical waveguide to be connected. Is connected between the optical amplifier and the optical wavelength multiplexer / demultiplexer D-1 on one side. Of the inserted optical isolator, an optical amplifier according to claim 9 in which the optical isolator downlink between the optical amplifying section and one side of the optical wavelength multiplexing and demultiplexing device D-2 is being inserted. 19. An optical wavelength multiplexer / demultiplexer C for optically multiplexing / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, wherein a group of upstream wavelength channels is divided without overlapping the wavelength channels. For each sub-group smaller than the number of wavelength channels, the number of optical wavelength multiplexer / demultiplexers D-1, D-2,... Equal to the number of sub-groups for multiplexing / branching all wavelength channels belonging to each sub-group. , D-m, a sub-group that branches all wavelength channels belonging to each sub-group for each sub-group of less than the number of wavelength channels obtained by dividing the group of downstream wavelength channels without overlapping the wavelength channels. , D-n, the optical wavelength multiplexer / demultiplexer C and the optical wavelength multiplexer / demultiplexer D-1, D-2, ...,
D-m, an optical waveguide for interconnecting ports corresponding to the wavelengths of the upstream wavelength channel on the side branched to each wavelength channel, and an optical wavelength multiplexer / demultiplexer C and an optical wavelength multiplexer / demultiplexer D-m. m + 1, D-m +
2,..., D-n, optical waveguides interconnecting the ports corresponding to the wavelengths for the downstream wavelength channel on the side branched to each wavelength channel, and optical isolators equal in number to the number of subgroups i: E-
K-1, i: EK-2, ..., i: EK-m, i: EK-m + 1, i:
EK-m + 2,..., I: EK-n, optical wavelength multiplexer / demultiplexers D-1, D-2,. , D-m and the optical input / output port and the optical isolator i: EK-1, i: EK-2,..., I: EK-m An optical waveguide for connecting the optical wavelength division multiplexers D-m + 1, D-m + 2,..., D-n so as to restrict the propagation direction of the signal light in the downstream direction. Are connected to the input / output port on the side where all are coupled and the optical isolator i: EK-m + 1, i: EK-m + 2, ..., i: EK-n. 10. The optical amplifier according to claim 9, further comprising an optical amplifier between each optical isolator of the two optical isolator means having a wave path via an optical waveguide. 20. An optical wavelength multiplexer / demultiplexer C for optically coupling / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, wherein a group of upstream wavelength channels is divided without overlapping the wavelength channels. For each sub-group smaller than the number of wavelength channels, the number of optical wavelength multiplexer / demultiplexers D-1, D-2,... Equal to the number of sub-groups for multiplexing / branching all wavelength channels belonging to each sub-group. , D-m, a sub-group that branches all wavelength channels belonging to each sub-group for each sub-group of less than the number of wavelength channels obtained by dividing the group of downstream wavelength channels without overlapping the wavelength channels. , D-n, the optical wavelength multiplexer / demultiplexer C and the optical wavelength multiplexer / demultiplexer D-1, D-2, ...,
D-m, an optical waveguide for interconnecting ports corresponding to the wavelengths of the upstream wavelength channel on the side branched to each wavelength channel, and an optical wavelength multiplexer / demultiplexer C and an optical wavelength multiplexer / demultiplexer D-m. m + 1, D-m +
2,..., D-n, optical waveguides interconnecting the ports corresponding to the wavelengths for the downstream wavelength channel on the side branched to each wavelength channel, and optical isolators equal in number to the number of subgroups i: E-
K-1, i: EK-2, ..., i: EK-m, i: EK-m + 1, i:
EK-m + 2,..., I: EK-n, optical wavelength multiplexer / demultiplexers D-1, D-2,. , D-m and the optical input / output port and the optical isolator i: EK-1, i: EK-2,..., I: EK-m An optical waveguide for connecting the optical wavelength division multiplexers D-m + 1, D-m + 2,..., D-n so as to restrict the propagation direction of the signal light in the downstream direction. Are connected to the input / output port on the side where all are coupled and the optical isolator i: EK-m + 1, i: EK-m + 2, ..., i: EK-n. One optical isolator means having a waveguide, an optical wavelength multiplexer / demultiplexer C for optically coupling / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, and all wavelength channels are divided without overlapping. For each subgroup less than the number of wavelength channels, each subgroup All of the number of optical wavelength division multiplexer D-1 equal to the number of subgroups that if branching wavelength channels belonging,
D-2, ..., D-m, D-m + 1, D-m + 2, ..., D-n Optical wavelength multiplexer / demultiplexer C and optical wavelength multiplexer / demultiplexer D-1, D -2, ...,
D-n, each of which has an optical waveguide interconnecting the corresponding wavelength channel port on the side branched to each wavelength channel, and the other light including an optical isolator arranged in each of the branched individual optical waveguides. 6. The optical amplifier according to claim 5, further comprising: an isolator, and an optical amplifier that connects the two optical isolators to each other. 21. An optical wavelength multiplexer / demultiplexer C for optically multiplexing / branching between one optical waveguide and an individual optical waveguide for each wavelength channel, wherein a group of upstream wavelength channels is divided without overlapping wavelength channels. For each sub-group smaller than the number of wavelength channels, the number of optical wavelength multiplexer / demultiplexers D-1, D-2,... Equal to the number of sub-groups for multiplexing / branching all wavelength channels belonging to each sub-group. , D-m, a sub-group that branches all wavelength channels belonging to each sub-group for each sub-group of less than the number of wavelength channels obtained by dividing the group of downstream wavelength channels without overlapping the wavelength channels. , D-n, the optical wavelength multiplexer / demultiplexer C and the optical wavelength multiplexer / demultiplexer D-1, D-2, ...,
D-m, an optical waveguide for interconnecting ports corresponding to the wavelengths of the upstream wavelength channel on the side branched to each wavelength channel, and an optical wavelength multiplexer / demultiplexer C and an optical wavelength multiplexer / demultiplexer D-m. m + 1, D-m +
2,..., D-n, optical waveguides interconnecting ports corresponding to the wavelengths of the downstream wavelength channel on the side branched to each wavelength channel, and optical isolators of a smaller number than the number of subgroups i: E
−K-1, i: EK-2, ..., i: EK-p, i: EK-p + 1,
i: E−K−p + 2,..., i: E−K−s, and the optical wavelength multiplexer / demultiplexers D−1, D−2, .., D-m, part D-1, D
-2,..., The input / output port and optical isolator i: EK-1, i:
EK-2,..., I: an optical waveguide connecting the EK-p, and an optical wavelength multiplexer / demultiplexer D-m + 1, so as to restrict the propagation direction of the signal light in the downward direction. Some of D-m + 2, ..., D-n D-p
+1, D−p + 2,..., D−s, the input / output port and the optical isolator i: E−
K-p + 1, i: E-K-p + 2, ..., i: One optical isolator means comprising an optical waveguide connecting the E-K-s, one optical waveguide and each wavelength channel An optical wavelength multiplexer / demultiplexer C for optically coupling / branching between individual optical waveguides, and belonging to each subgroup for each subgroup of a number smaller than the number of wavelength channels obtained by dividing all wavelength channels without overlapping. The number of optical wavelength multiplexer / demultiplexers D-1 equal to the number of subgroups for multiplexing / demultiplexing all wavelength channels
, D-m, D-m + 1, D-m + 2,..., D-n, the optical wavelength multiplexer / demultiplexer C and the optical wavelength multiplexer / demultiplexer D-1, D-2, ...,
D-n, the optical waveguides interconnecting the corresponding wavelength channel ports on the side branched to each wavelength channel, and the optical wavelength multiplexer / demultiplexer D among the individual branched optical waveguides. -1, D-2, ..., D-p, D-p + 1, D-p +
2,..., The other optical isolator having an optical isolator disposed in each optical waveguide of the optical wavelength multiplexer / demultiplexer corresponding to other than D-s, and an optical amplifier for connecting both optical isolator to each other 6. The optical amplifier according to claim 5, further comprising means. 22. A part or the whole of a waveguide connecting between input and output ports of a corresponding wavelength channel on a branching side for each wavelength channel of a wavelength multiplexer / demultiplexer, respectively. 13. An optical variable intensity adjuster capable of changing an output signal intensity of the signal light.
20. The optical amplifier according to any one of claims 19 to 19.