JP2003234722A - Optical wavelength multiplex access network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make two-way transmission possible by using light of a fixed optical frequency interval based on a standardized frequency while using a batch multi-wavelength generation light source for an OSU. <P>SOLUTION: A wavelength multiplexing/demultiplexing means is provided with a first WDM coupler for demultiplexing the modulated light of a wavelength band λd and the non-modulated light of a wavelength band λu transmitted from the OSU to respective bands, a first wavelength separator for demultiplexing the modulated light of the wavelength band λd to respective wavelengths λd1 to λdn, a second wavelength separator for demultiplexing the non-modulated light of the wavelength band λu to respective wavelengths λu1 to λun, (n) pieces of second WDM couplers for respectively multiplexing and transmitting the modulated light of a wavelength λdi and the non-modulated light of a wavelength λui to each ONUi, and a wavelength multiplexer for multiplexing the modulated light of the wavelengths λu1 to λun transmitted from each ONUi and transmitting the multiplexed light to the OSU. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center device (OS
U) and an optical network unit without light source (ON
U) The present invention relates to an optical wavelength division multiplexing access network for bidirectionally transmitting an optical signal to and from the optical network.

[0002]

2. Description of the Related Art FIG. 6 shows a configuration example of a conventional optical WDM access network (Japanese Patent Laid-Open No. 2000-196536).
Issue). Here, one wavelength band λd is allocated for the downlink signal from the OSU to the ONU, and
An example is shown in which one wavelength band λu (≠ λd) is assigned for the upstream signal to the ONU, and wavelengths λd1 to λdn of the wavelength band λd and wavelengths λu1 to λun of the wavelength band λu are assigned to the respective ONUs.

The transmitter 11 of the OSU 10 WDMs the down-modulated light of the wavelength band λd output from the multi-wavelength batch generation / modulation unit 12 and the unmodulated light of the wavelength band λu output from the multi-wavelength batch generation unit 13. Wavelength multiplex is performed by the coupler 14, and wavelength multiplexing / demultiplexing means (MUX / DEMU) is performed via the optical fiber transmission line 1.
X) 20. The wavelength demultiplexing means 20 demultiplexes the down-modulated light in the wavelength band λd and the unmodulated light in the wavelength band λu, respectively, and obtains the down-modulated light in the wavelengths λd1 to λdn and the wavelengths λu1 to λ.
The unmodulated light of un is transmitted to the corresponding ONUs 30-1 to 30-n via the optical fiber transmission line 3.

The ONU 30-1 demultiplexes the down-modulated light of wavelength λd1 and the unmodulated light of wavelength λu1 by the WDM coupler 31, receives the down-modulated light of wavelength λd1 by the optical receiver 32, and outputs the wavelength λu1.
The non-modulated light is modulated by the optical modulator 33 and transmitted as an upstream signal to the wavelength division multiplexer 20 via the optical fiber transmission line 4. The same applies to other ONUs. Wavelength λu1 to λ
The upstream modulated light of un is multiplexed by the wavelength demultiplexing means 20, transmitted to the OSU 10 through the upstream optical fiber transmission line 2, and received by the receiving unit 15.

The wavelength band λd (n wavelengths) of the down-modulated light and the wavelength band λu (n wavelengths) of the up-modulated light are on the optical frequency axis (or on the wavelength axis) as shown in FIG. It is arranged so that it does not overlap with the above). This will turn on all
In U, the same WDM coupler 31 that separates / multiplexes the wavelength band λd and the wavelength band λu can be used.

[0006]

By the way, an arrayed waveguide diffraction grating (AWG) which is supposed to be used as the wavelength demultiplexing means 20 is capable of demultiplexing wavelength-division-multiplexed light for each wavelength, and a plurality of different wavelengths. It has the characteristic of being able to combine the light of. Further, the AWG has a characteristic of simultaneously multiplexing / demultiplexing wavelengths having an FSR (free spectrum range) interval (Japanese Patent Laid-Open No. 2000-206362). Due to the characteristics of this FSR, the downlink signal wavelength (for example, λd1) and the uplink signal wavelength (for example, λu1) can be demultiplexed to the same port.

However, the FSR of the AWG has a constant interval in the wavelength region, but does not have a constant interval in the optical frequency region. For example, optical frequency 193.100 T at port i
Hz (wavelength 1552.524 nm) is transmitted, and port i + 1
Consider a case in which the FSR of an AWG that transmits light having an optical frequency of 193.000 THz (wavelength 1553.329 nm) is designed to be 30.329 nm. With this FSR, when the port i transmits light with an optical frequency of 189.400 THz (wavelength 1582.853 nm), the port i + 1 has an optical frequency of 189.3038 THz (wavelength 15
It will transmit light of 83.658 nm). That is,
The optical frequency interval between light and light was 100 GHz,
The optical frequency interval between light and light is calculated to shift to 96.2 GHz.

In this way, as shown in FIG. 6, in the configuration in which the lights of different upstream and downstream bands are collectively separated by utilizing the FSR of the AWG, when 10 wavelengths are multiplexed to a large number of ONUs, 30 wavelengths are multiplexed. %, When 20 wavelengths are multiplexed, 60% or more of the ports will have a difference in transmitted light frequency, so many ONUs
Will be difficult to accommodate.

On the other hand, as a light source arranged in the transmitter 11 of the OSU 10, a multi-wavelength batch generation light source that collectively generates light of each wavelength channel is used. This multi-wavelength batch generation light source inputs light with a single center wavelength into an optical modulator and modulates it with a periodic signal of a predetermined frequency from a single frequency generation source to generate a frequency corresponding to the frequency of the periodic signal. There is one that collectively generates multi-wavelength light at intervals (Japanese Patent Application No. 2001-19).
9791, Japanese Patent Application No. 2000-266125).

On the other hand, the wavelength used in the optical WDM network is 193.100 THz in ITU-T.
Centered around the optical frequency constant interval (100 GHz interval, 50 GHz
The intervals etc.) are standardized.

Although the above-mentioned multi-wavelength batch generation light source can deal with such a standardized frequency, the output light frequency of this multi-wavelength batch generation light source cannot be adjusted to the transmitted light frequency of the AWG since it has a constant interval. That is, the AW having the configuration of FIG.
In order to match the transmission light frequency of G, it is necessary to deal with individual light sources, but in this case, the standardized frequency cannot be used.

Further, in the configuration of FIG. 6, the ports of the AWG are alternately used for the upstream signal and the downstream signal, and the utilization frequency interval of the upstream signal (or the downstream signal) is
The frequency interval must be doubled for each port of the AWG, and it is difficult to increase the number of ONUs (number of wavelengths).

An object of the present invention is to provide an optical wavelength division multiple access network which uses a multi-wavelength batch generation light source for an OSU and enables bidirectional transmission using light having a constant optical frequency interval in accordance with a standardized frequency. To do.

[0014]

SUMMARY OF THE INVENTION The present invention is an AWG FS
R in R is not used to separate the lights in the different upstream and downstream bands at once, but the modulated light in the wavelength band λd, the unmodulated light in the wavelength band λu, and the modulated light in the wavelength band λu are used by individual AWGs. And separate / multiplex each.

The invention of claim 1 is the center unit (OSU).
And multiple optical network units (O
NU) via wavelength demultiplexing means and an optical fiber transmission line, and wavelength bands λd and λu different from each other are allocated for a downstream signal from the OSU to each ONU and for an upstream signal from each ONU to the OSU. , Each ONU
, N, which are different wavelengths from the wavelength bands λd and λu, respectively (λd1, λu1), (λd2, λu1), ..., (λd
n, λun), the OSU determines the wavelength band λd
Modulated light and unmodulated light in the wavelength band λu are transmitted, and each ON
Ui (i is an integer of 1 to n) receives the modulated light of the wavelength λdi assigned to each, and modulates the unmodulated light of the wavelength λui assigned to each to transmit as an upstream signal,
In the optical wavelength multiplexing access network in which the OSU receives the modulated light of the wavelength λui transmitted as an upstream signal from each ONUi, the wavelength demultiplexing means includes the modulated light of the wavelength band λd and the wavelength band λu transmitted from the OSU. First WDM coupler that demultiplexes the unmodulated light of
A first wavelength demultiplexer that demultiplexes the modulated light of d into wavelengths λd1 to λdn, a second wavelength demultiplexer that demultiplexes the unmodulated light of wavelength band λu into wavelengths λu1 to λun, and a wavelength demultiplexer of wavelength λdi Modulated light and wavelength λ
n number of second WDM couplers that combine unmodulated light of ui and transmit to each ONUi, and wavelength multiplexing that combines modulated lights of wavelengths λu1 to λun transmitted from each ONUi and transmit to OSU And a container.

According to a second aspect of the present invention, the wavelength demultiplexing means separates the modulated light of the wavelength band λd and the unmodulated light of the wavelength band λu transmitted from the OSU into respective bands, and the wavelength band λ.
The first wavelength demultiplexer that demultiplexes the modulated light of d into each wavelength λd1 to λdn, and the second wavelength that demultiplexes the unmodulated light of the wavelength band λu into each wavelength λu1 to λun and transmits to each ONUi. Separator, modulated light of wavelength λdi to be transmitted to each ONUi, and each ONU
n second WDM couplers that demultiplex the modulated light of wavelength λ ui transmitted from i and the wavelength λ transmitted from each ONU i.
A wavelength multiplexer that multiplexes the modulated lights of u1 to λun and transmits the multiplexed lights to the OSU.

Here, the wavelength demultiplexing means is the wavelength band λd.
The first wavelength demultiplexer that demultiplexes the modulated light of each wavelength into each wavelength, the second wavelength demultiplexer that demultiplexes the unmodulated light of wavelength band λu into each wavelength, and the modulated light of each wavelength of wavelength band λu An arrayed waveguide diffraction grating having a free spectral range (FSR) of each band or more is used as a wavelength multiplexer for multiplexing (claim 3). The wavelength demultiplexing means includes a first WDM coupler that demultiplexes the modulated light of the wavelength band λd and the unmodulated light of the wavelength band λu into each band, and a first WDM coupler that demultiplexes the modulated light of the wavelength band λd into each wavelength. Instead of the wavelength demultiplexer of No. 1 and the second wavelength demultiplexer that demultiplexes the unmodulated light of wavelength band λu into each wavelength, the free spectral range (FSR) above the combined band of wavelength band λd and wavelength band λu It may be configured to use one arrayed waveguide diffraction grating having the above (claim 4).

Further, as the light source of the transmitting unit for transmitting the modulated light in the wavelength band λd and the unmodulated light in the wavelength band λu by the OSU,
Light with a single center wavelength is input to an optical modulator, modulated with a periodic signal of a predetermined frequency from a single frequency source, and multi-wavelength light with a frequency interval corresponding to the frequency of the periodic signal is generated collectively. A wavelength collective light source is used (Claim 5).

The invention of claim 6 is the center unit (OSU).
And multiple optical network units with light sources (ON
U) is connected through wavelength demultiplexing means and an optical fiber transmission line, and different wavelength bands λd and λu are allocated for a downstream signal from the OSU to each ONU and for an upstream signal from each ONU to the OSU. , Each ONU1,
2, ..., N, which have different wavelengths (λd1, λu1), (λd2, λu1), ... (λdn, λ) from the wavelength bands λd and λu.
un), the OSU transmits the modulated light of the wavelength band λd, each ONUi (i is an integer of 1 to n) receives the modulated light of the assigned wavelength λdi, and is allocated to each of them. In the optical WDM access network having a configuration in which the unmodulated light of wavelength λui is modulated and transmitted as an upstream signal, and the OSU receives the modulated light of wavelength λui transmitted as an upstream signal from each ONUi, Is a wavelength demultiplexer that demultiplexes the modulated light of the wavelength band λd transmitted from the OSU into each wavelength λd1 to λdn, the modulated light of the wavelength λdi transmitted to each ONUi, and the modulated light of the wavelength λui transmitted from each ONUi. It is provided with n WDM couplers for demultiplexing, and a wavelength multiplexer for multiplexing the modulated lights of wavelengths λu1 to λun transmitted from each ONUi and transmitting them to the OSU.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) FIG. 1 shows a first embodiment of an optical WDM access network of the present invention. Here, like the conventional configuration, the OSU turns on.
One wavelength band λd is allocated for the downlink signal to U,
One wavelength band λ for upstream signals from ONU to OSU
u (≠ λd) is assigned, and the wavelength λd1 ~
λdn and the wavelengths λu1 to λun of the wavelength band λu are respectively O
An example of assigning to a NU will be shown.

In the figure, the transmitter 11 of the OSU 10 is
Wavelength band λd output from multi-wavelength batch generation / modulation unit 12
WDM coupler 14 wavelength-demultiplexes the down-modulated light of W and the unmodulated light of the wavelength band λu output from the multi-wavelength batch generation unit 13, and the wavelength demultiplexing means 20 through the optical fiber transmission line 1.
Send to A. As shown in FIG. 2, the multi-wavelength batch generation / modulation unit 12 uses the wavelength demultiplexer (DMX) 122 to convert the unmodulated light of the wavelength band λd output from the multi-wavelength batch generation light source 121 into light of each wavelength λd1 to λdn. Optical modulator 123-1 to
In the configuration, a signal addressed to each ONU is modulated by 123-n, and multiplexed by a wavelength multiplexer (MUX) 124.

The wavelength division multiplexer / demultiplexer 20A is a WDM coupler 21, 22-1, which performs demultiplexing of the wavelength band λd and the wavelength band λu.
22-n, a wavelength demultiplexer (DMX) 24 for demultiplexing light having wavelengths λd1 to λdn in the wavelength band λd, and a wavelength λ in the wavelength band λu.
a wavelength demultiplexer (DMX) 25 for demultiplexing light of u1 to λun,
It is composed of a wavelength multiplexer (MUX) 26 that multiplexes lights of wavelengths λu1 to λun in the wavelength band λu. The optical amplifier may be arranged at an appropriate position such as the input side of the wavelength demultiplexers 24 and 25 or the output side of the wavelength multiplexer 26. However,
The optical amplifiers arranged on the input sides of the wavelength demultiplexers 24 and 25 need only be able to individually amplify the respective wavelength bands λd and λu.
The optical amplifier arranged on the output side of the wavelength multiplexer 26 has a wavelength band λ
A band for collectively amplifying both d and λu is required. The same applies to the embodiments described below.

Downstream modulated light of the wavelength band λd input to the wavelength demultiplexing means 20A from the optical fiber transmission line 1 and the wavelength band λ
The unmodulated light of u is demultiplexed into each band by the WDM coupler 21, and demultiplexed into each wavelength by the wavelength demultiplexers (DMX) 24 and 25. Down-modulated light of wavelength λd1 and unmodulated light of wavelength λu1
The optical fiber transmission line 3 is multiplexed by the WDM coupler 22-1.
Is transmitted to the ONU 30-1 via. Down-modulated light and non-modulated light of other wavelengths are similarly transmitted to each OUN.

The ONU 30-1 demultiplexes the down-modulated light of wavelength λd1 and the unmodulated light of wavelength λu1 by the WDM coupler 31, receives the down-modulated light of wavelength λd1 by the optical receiver 32, and outputs the wavelength λu1.
The unmodulated light is modulated by the optical modulator 33 and transmitted as an upstream signal to the wavelength demultiplexing / demultiplexing means 20A via the optical fiber transmission line 4. The same applies to other ONUs. The upstream modulated lights of wavelengths λu1 to λun input to the wavelength demultiplexing means 20A are multiplexed by the wavelength multiplexer (MUX) 26, transmitted to the OSU 10 via the optical fiber transmission line 2, and received by the receiving unit 15. .

Wavelength demultiplexing means 20A as shown above
The wavelength demultiplexers 24 and 25 and the wavelength multiplexer 26 each have a configuration of multiplexing and demultiplexing light of one wavelength band, and the AWG has a periodic wavelength transmission characteristic (FSR) which has been conventionally required.
It is not necessary to collectively combine and demultiplex multiple wavelength bands using the. That is, when configuring the optical wavelength division multiplexing access network, it is not necessary to consider the optical frequency shift when using the AWG FSR described above, and each wavelength of the two wavelength bands has a frequency constant interval defined by the ITU. Can be set to a value. Further, a multi-wavelength batch generation light source using a single frequency generation source with a constant frequency interval can be used as the light source.

(Another Configuration Example of Wavelength Multiplexing / Demultiplexing Means 20A)
FIG. 3 shows another configuration example of the wavelength demultiplexing means 20A.
In this configuration example, the WDM coupler 21 and the wavelength demultiplexers (DMX) 24 and 25 shown in FIG.
X) 27. Wavelength separator (DM
X) 27, light having wavelengths λd1 to λdn in the wavelength band λd,
An equivalent function can be realized by using a large-scale one capable of demultiplexing light of wavelengths λu1 to λun in the wavelength band λu without using the FSR.

(Second Embodiment) FIG. 4 shows a second embodiment of the optical WDM access network of the present invention.
In the figure, the components of the OSU 10, the wavelength demultiplexing means 20B, and each of the OUNs 30-1 to 30-n are the same as those of the first embodiment. The transmitter 11 of the OSU 10 transmits the down-modulated light in the wavelength band λd and the unmodulated light in the wavelength band λu to the wavelength demultiplexing means 20B via the optical fiber transmission line 1.

Downstream modulated light of the wavelength band λd input to the wavelength demultiplexing means 20B from the optical fiber transmission line 1 and the wavelength band λ.
The unmodulated light of u is demultiplexed into each band by the WDM coupler 21, and demultiplexed into each wavelength by the wavelength demultiplexers (DMX) 24 and 25. The downlink modulated light of wavelength λd1 is transmitted by the WDM coupler 22-d.
It is transmitted to the ONU 30-1 via the optical fiber transmission line 3. In addition, the unmodulated light of wavelength λu1 is transmitted through the optical fiber transmission line 4
Is transmitted to the ONU 30-1 via. Down-modulated light and non-modulated light of other wavelengths are similarly transmitted to each OUN.

The ONU 30-1 receives the down-modulated light of wavelength λd1 input from the optical fiber transmission line 3 from the WDM coupler 31.
The signal is received by the optical receiver 32 via. Optical fiber transmission line 4
The unmodulated light having the wavelength λu1 input from is modulated by the optical modulator 33 and transmitted as an upstream signal to the wavelength demultiplexing means 20B via the WDM coupler 31 and the optical fiber transmission line 3. The same applies to other ONUs.

The upstream modulated lights of wavelengths λu1 to λun input from the optical fiber transmission line 3 to the wavelength demultiplexing means 20B are separated from the downstream signal lights by the WDM couplers 22-1 to 22-n, respectively, and then the wavelength multiplexer (MUX). ) 26, the optical signal is transmitted to the OSU 10 via the optical fiber transmission line 2, and is received by the receiving unit 15.

Thus, the W of the wavelength demultiplexing means 20B is
DM couplers 22-1 to 22-n and each ONU 30-1 to
The WDM coupler 31 of 30-n has a configuration for separating the downstream signal light of the wavelength band λd and the upstream signal light of the wavelength band λu, and is an optical connection between the wavelength demultiplexing means 20B and each OUN 30-1 to 30-n. The optical signals of the fiber transmission lines 3 and 4 are different from those of the first embodiment.

The wavelength demultiplexing means 20 of the present embodiment.
B WDM coupler 21 and wavelength demultiplexer (DMX) 2
The wavelengths 4 and 25 can also be replaced with a single wavelength demultiplexer (DMX) 27 as shown in FIG.

(Third Embodiment) FIG. 5 shows a third embodiment of the optical WDM access network of the present invention.
The feature of this embodiment is that each ONU 30-1 to 30-n has
Each of the light modulators 3 has a light source 34 having a wavelength of λu1 to λun.
It is in the place where it is modulated by 3 to obtain upstream modulated light.

In the figure, the transmitter 11 of the OSU 10 is
Wavelength band λd output from multi-wavelength batch generation / modulation unit 12
And transmits the down-modulated light to the wavelength demultiplexing means 20C via the optical fiber transmission line 1.

The wavelength demultiplexing means 20C is a WDM coupler 22-1 to 22 for multiplexing / demultiplexing the wavelength band λd and the wavelength band λu.
-N, a wavelength demultiplexer (DMX) 24 that demultiplexes light having wavelengths λd1 to λdn in the wavelength band λd, and wavelengths λu1 to λ in the wavelength band λu.
It is composed of a wavelength multiplexer (MUX) 26 that multiplexes the light of un.

The down-modulated light of the wavelength band λd inputted from the optical fiber transmission line 1 to the wavelength demultiplexing means 20C is demultiplexed into each wavelength by the wavelength demultiplexer (DMX) 24. The downlink modulated light of wavelength λd1 is transmitted to the ONU 30-1 via the WDM coupler 22-d optical fiber transmission line 3. Similarly, downlink modulated lights of other wavelengths are also transmitted to the respective OUNs.

The ONU 30-1 receives the down-modulated light having the wavelength λd1 input from the optical fiber transmission line 3 from the WDM coupler 31.
The signal is received by the optical receiver 32 via. The unmodulated light of the wavelength λu1 output from the light source 34 is modulated by the optical modulator 33 and transmitted as an upstream signal to the wavelength demultiplexing means 20C via the WDM coupler 31 and the optical fiber transmission line 3. The same applies to other ONUs.

The upstream modulated lights of wavelengths λu1 to λun input from the optical fiber transmission line 3 to the wavelength demultiplexing means 20C are separated from the downstream signal lights by the WDM couplers 22-1 to 22-n, respectively, and then the wavelength multiplexer (MUX). ) 26, the optical signal is transmitted to the OSU 10 via the optical fiber transmission line 2, and is received by the receiving unit 15.

[0039]

As described above, the optical WDM access network of the present invention has a structure in which the wavelength demultiplexer and the wavelength demultiplexer that compose the wavelength demultiplexing unit combine and demultiplex light in one wavelength band. Yes, previously required AW
The collective multiplexing / demultiplexing of a plurality of wavelength bands using the G FSR is unnecessary. As a result, each wavelength of the two wavelength bands used in the upstream and the downstream in the optical WDM access network is I
The value can be set to a value with a fixed frequency interval defined by TU. Further, a multi-wavelength batch generation light source using a single frequency generation source with a constant frequency interval can be used as the light source.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of an optical WDM access network of the present invention.

FIG. 2 is a diagram showing a configuration example of a multi-wavelength batch generation / modulation unit 12.

FIG. 3 is a diagram showing a configuration example of a wavelength demultiplexing unit 20A.

FIG. 4 is a diagram showing a second embodiment of an optical wavelength division multiplexing access network of the present invention.

FIG. 5 is a diagram showing a third embodiment of an optical wavelength division multiplexing access network of the present invention.

FIG. 6 is a diagram showing a configuration example of a conventional optical wavelength multiplexing access network.

[Explanation of symbols]

1, 2, 3, 4 optical fiber transmission line 10 Center unit (OSU) 11 Transmitter 12 Multi-wavelength batch generation / modulation unit 13 Multi-wavelength batch generator 14 WDM coupler 15 Receiver 20, 20A, 20B, 20C Wavelength demultiplexing means 21,22 WDM coupler 24, 25, 27 Wavelength demultiplexer (DMX) 26 Wavelength Multiplexer (MUX) 30 Optical Network Unit (ONU) 31 WDM coupler 32 optical receiver 33 Optical modulator 34 light source

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koji Akimoto             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 5K002 AA01 AA03 BA05 CA14 DA02                       DA04 FA01

Claims (6)

[Claims] 1. A center unit (OSU) and a plurality of optical network units (ONUs) having no light source are connected via wavelength demultiplexing means and optical fiber transmission lines, and the OSUs each ONU. Different wavelength bands λd and λu are assigned for the downstream signals to the OSU and the upstream signals from the ONUs to the OSU.
Nu1, 2, ..., N have different wavelengths (λd1, λu1), (λd2, λu1), ...
When (λdn, λun) is assigned, the OSU transmits modulated light in the wavelength band λd and unmodulated light in the wavelength band λu, and each ONUi (i is 1 to 1).
(integer of n) receives the modulated light of the allocated wavelength λdi and modulates the unmodulated light of the allocated wavelength λui to transmit as an upstream signal, and the OSU is transmitted as an upstream signal from each ONUi. In the optical wavelength division multiplexing access network configured to receive the modulated light of the wavelength λui, the wavelength demultiplexing unit may transmit the modulated light of the wavelength band λd and the unmodulated light of the wavelength band λu transmitted from the OSU. A first WDM coupler for demultiplexing into a band and the wavelength band λd
First wavelength demultiplexer for demultiplexing the modulated light of each wavelength λd1 to λdn, a second wavelength demultiplexer demultiplexing the unmodulated light of the wavelength band λu into each wavelength λu1 to λun, and a wavelength λdi of The n second WDM couplers that combine the modulated light and the unmodulated light of the wavelength λui and transmit the multiplexed lights to the respective ONUi, and the modulated lights of the wavelengths λu1 to λun transmitted from the respective ONUi, and combine the OSUs. An optical WDM access network, comprising: 2. A center unit (OSU) and a plurality of optical network units (ONUs) having no light source are connected via wavelength demultiplexing means and an optical fiber transmission line, and each OSU is connected to each ONU. Different wavelength bands λd and λu are assigned for the downstream signals to the OSU and the upstream signals from the ONUs to the OSU.
Nu1, 2, ..., N have different wavelengths (λd1, λu1), (λd2, λu1), ...
When (λdn, λun) is assigned, the OSU transmits modulated light in the wavelength band λd and unmodulated light in the wavelength band λu, and each ONUi (i is 1 to 1).
(integer of n) receives the modulated light of the allocated wavelength λdi and modulates the unmodulated light of the allocated wavelength λui to transmit as an upstream signal, and the OSU is transmitted as an upstream signal from each ONUi. In the optical wavelength division multiplexing access network configured to receive the modulated light of the wavelength λui, the wavelength demultiplexing unit may transmit the modulated light of the wavelength band λd and the unmodulated light of the wavelength band λu transmitted from the OSU. A first WDM coupler for demultiplexing into a band and the wavelength band λd
First wavelength demultiplexer for demultiplexing the modulated light of each wavelength λd1 to λdn and a second wavelength demultiplexing the unmodulated light of the wavelength band λu into each wavelength λu1 to λun and transmitting to each ONUi. Separator, modulated light of wavelength λdi to be transmitted to each ONUi, and each ON
N second WDM couplers that demultiplex the modulated light of wavelength λui transmitted from Ui, and a wavelength multiplexer that multiplexes the modulated light of wavelengths λu1 to λun transmitted from each ONUi and transmits to the OSU. An optical WDM access network characterized by comprising: 3. The optical WDM access network according to claim 1 or 2, wherein the wavelength demultiplexing unit includes a first wavelength demultiplexer that demultiplexes the modulated light of the wavelength band λd into each wavelength. A second wavelength demultiplexer that demultiplexes unmodulated light in the wavelength band λu into each wavelength and a wavelength multiplexer that multiplexes modulated light in each wavelength in the wavelength band λu are used as a free spectral range (FSR) above each band. The optical wavelength division multiple access network characterized by having a configuration using an arrayed-waveguide diffraction grating having 4. The optical WDM access network according to claim 1, wherein the WDM demultiplexing unit demultiplexes the modulated light in the wavelength band λd and the unmodulated light in the wavelength band λu into respective bands. Instead of the first WDM coupler, the first wavelength demultiplexer that demultiplexes the modulated light of the wavelength band λd into each wavelength, and the second wavelength demultiplexer that demultiplexes the unmodulated light of the wavelength band λu into each wavelength. , Wavelength band λd and wavelength band λu
Free spectral range (FS
An optical WDM access network, characterized in that it is configured to use one arrayed waveguide diffraction grating having R). 5. The optical WDM access network according to claim 1 or 2, wherein a single light source is used as a light source of a transmitting unit that transmits the modulated light in the wavelength band λd and the unmodulated light in the wavelength band λu in the OSU. The light of the center wavelength of is input to the optical modulator, modulated by the periodic signal of the specified frequency from the single frequency source, and the multi-wavelength batch is generated to generate the multi-wavelength light of the frequency interval corresponding to the frequency of the periodic signal. An optical WDM access network characterized by using a generated light source. 6. A center unit (OSU) and a plurality of optical network units (ONUs) each having a light source are connected via a wavelength demultiplexing means and an optical fiber transmission line, and the OSUs are connected to the respective ONUs. Different wavelength bands λd and λu are allocated for the downstream signal and for the upstream signal from each of the ONUs to the OSU.
, N, which are different wavelengths from the wavelength bands λd and λu, respectively (λd1, λu1), (λd2, λu1), ..., (λd
n, λun), the OSU transmits the modulated light of the wavelength band λd, and each ONUi (i is an integer of 1 to n) receives the modulated light of the assigned wavelength λdi. An optical wavelength division multiplexing access network having a configuration in which unmodulated light having a wavelength λui assigned thereto is modulated and transmitted as an upstream signal, and the OSU receives the modulated light having a wavelength λui transmitted as an upstream signal from each ONUi. In the wavelength division demultiplexing means, the wavelength demultiplexer for demultiplexing the modulated light of the wavelength band λd transmitted from the OSU into each wavelength λd1 to λdn, the modulated light of the wavelength λdi to be transmitted to each ONUi, and each ONUi N to demultiplex the transmitted modulated light of wavelength λui
WDM couplers and the wavelength λ transmitted from each ONUi
An optical WDM access network comprising: a wavelength multiplexer for multiplexing modulated lights of u1 to λun and transmitting the multiplexed lights to the OSU.