JPWO2007108126A1 - Point-multipoint optical communication system - Google Patents

Abstract

A point-multipoint optical communication system that enables cost reduction of a subscriber side apparatus is obtained. One station side device and a plurality of subscriber side devices are connected by an optical network via a wavelength multiplexer / demultiplexer and an optical fiber transmission line, and optical signals are respectively transmitted to the optical network by time division multiplexing or wavelength multiplexing. In the output point-multipoint optical communication system, the center wavelength of the station side device and the center wavelength of the plurality of subscriber side devices are arranged in the equally spaced wavelength slot 21 having the wavelength slot width Δλd, and Δλd is Δλd1 + Δλd2 = Δλd and Δλd1 ≦ Δλd2 are divided into two wavelength slots, and in the downstream wavelength slot 22 having the wavelength slot width Δλd1, the center wavelength of the station side device is arranged, and the upstream wavelength slot having the wavelength slot width Δλd2 In the wavelength slot 23, the center wavelengths of a plurality of subscriber side devices are arranged.

Description

  The present invention relates to a point-multipoint optical communication system in which one or more station-side devices and a plurality of subscriber-side devices perform data transmission / reception using one optical network.

  As one form of point-multipoint optical communication system, a plurality of point-multipoint optical communication systems are multiplexed by wavelength multiplexing technology to increase the sharing efficiency of optical fiber transmission lines Point-multipoint optical communication Systems have been studied (see, for example, Patent Document 1 and Non-Patent Document 1).

  FIG. 8 is an illustration of wavelength arrangement in a conventional point-multipoint optical communication system (hereinafter abbreviated as point-multipoint optical communication system) to which optical wavelength multiplexing technology is applied. FIG. 9 is a block diagram of a conventional point-multipoint optical communication system using the wavelength arrangement shown in FIG.

  More specifically, FIG. 9 shows a point-multipoint optical communication system of a plurality of m (m is an integer of 2 or more) by applying an optical wavelength multiplexing technique when the wavelength arrangement shown in FIG. 8 is used. It is the block diagram by which (1 (1) -1 (m)) was multiplexed.

  The kth point-multipoint optical communication system 1 (k) among the multiplexed m is a station side device 2 (k) and a plurality of nk (nk is an integer of 2 or more) subscriber side. A star coupler that connects the devices 3 (k, 1) to 3 (k, nk), the station side device 2 (k) and a plurality of nk subscriber side devices 3 (k, 1) to 3 (k, nk). 4 (k), optical fiber 5, wavelength side multiplexer / demultiplexer 6 on the station side, wavelength multiplexer / demultiplexers 7, 8 and m couplers 9 (1) to 9 (m) are provided in the middle of the transmission line. And a wavelength multiplexing / demultiplexing unit 10.

  In addition, three of the optical fiber 5, the wavelength side multiplexer / demultiplexer 6 on the station side, and the wavelength multiplexing / demultiplexing unit 10 in the middle of the transmission path are a plurality of point-multipoint optical communication systems 1 (1) to 1 (m). In common.

  Here, the relationship between the conventional wavelength arrangement shown in FIG. 8 and the conventional point-multipoint optical communication system shown in FIG. 9 will be described. In the conventional wavelength arrangement shown in FIG. 8, with respect to the number m of the point-multipoint optical communication system multiplexed by applying the optical wavelength multiplexing technique, a plurality of m + 1 equally spaced wavelength slots 41 (determined by an equal wavelength interval Δλd) 0) to 41 (m) are defined.

  In the point-multipoint optical communication system shown in FIG. 9, one wavelength slot, for example, equally spaced wavelength slot 41 (0) is allocated to all downstream signal lights, and the remaining equally spaced wavelength slots 41 ( 1) to 41 (m) are allocated to upstream signal light from a plurality of subscriber-side devices in a plurality of m-point multi-point optical communication systems, thereby allowing a plurality of station-side devices 2 and a plurality of subscriber-side devices Data transmission / reception with the apparatus 3 is realized.

  However, when the wavelength arrangement as shown in FIG. 8 is used, the wavelength multiplexing / demultiplexing unit 10 in the middle of transmission needs to have a very complicated configuration. This is because, in order to transmit and receive data between the upstream signal light and the downstream signal light between the station side device 2 and the plurality of subscriber side devices 3, one of the wavelength multiplexing / demultiplexing units 10 is used. Although it is necessary to input / output from the port, the upstream signal light and the downstream signal light are arranged in the equally spaced wavelength slots 41 that are not the same. Cannot be realized.

  In order to realize a function that is input / output from one port of the wavelength multiplexing / demultiplexing unit 10, the wavelength multiplexing / demultiplexing unit 10 combines a plurality of (m + 1) equally spaced wavelength slots 41 (0) to 41 (m). A wavelength multiplexer / demultiplexer 7 that demultiplexes, a wavelength multiplexer / demultiplexer 8 that multiplexes and demultiplexes the wavelength multiplexed signal light in the downstream direction, and a plurality of signals that multiplex and branch the downlink signal light and the upstream signal light. It is necessary to configure from couplers 9 (1) to 9 (m).

JP 2004-222255 A D. Nesset, ECOC 2005, Tu. 1.3.1.

  However, the prior art has the following problems. The wavelength multiplexing / demultiplexing unit 10 that has to have such a complicated configuration is expensive as a result, and there is a problem that it is difficult to apply to an optical subscriber system that requires a low price.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a point-multipoint optical communication system that enables cost reduction of a subscriber-side device.

  In the point-multipoint optical communication system according to the present invention, one station-side device and a plurality of subscriber-side devices are connected by an optical network via a wavelength multiplexer / demultiplexer and an optical fiber transmission line. In a point-multipoint optical communication system in which each of a station side device and a plurality of subscriber side devices outputs an optical signal to an optical network by time division multiplexing or wavelength multiplexing, the central wavelength of the station side device and the plurality of subscriber sides The center wavelength of the device is arranged in one wavelength slot having a wavelength slot width Δλd, and the wavelength slot having the wavelength slot width Δλd has a first wavelength slot width Δλd1 and a second wavelength slot width Δλd2, and Δλd1 + Δλd2 = Δλd and is divided into two wavelength slots having a relationship of Δλd1 ≦ Δλd2 and has a first wavelength slot width Δλd1 The center wavelength of the station side device is arranged in the wavelength slot, and the center wavelengths of the plurality of subscriber side devices are arranged in the wavelength slot having the second wavelength slot width Δλd2.

  According to the present invention, the center wavelength of the station side device and the center wavelength of the plurality of subscriber side devices are individually arranged in a pair of wavelength slots obtained by dividing one wavelength slot, and the wavelength slot widths of the plurality of subscriber side devices are provided. Is wider than the wavelength slot width of the station-side device, a point-multipoint optical communication system that enables cost reduction of the subscriber-side device can be obtained.

It is a block diagram of the point-multipoint optical communication system in Embodiment 1 of this invention. It is the figure which showed wavelength arrangement | positioning of the point-multipoint optical communication system in Embodiment 1 of this invention. It is the block diagram by which the several m point-multipoint optical communication system in Embodiment 2 of this invention was multiplexed by wavelength multiplexing. It is the figure which showed the wavelength arrangement | positioning of the several m point-multipoint optical communication system in Embodiment 2 of this invention. It is the block diagram by which the several m point-multipoint optical communication system in Embodiment 3 of this invention was multiplexed by wavelength multiplexing. It is the figure which showed wavelength arrangement | positioning of the kth point-multipoint optical communication system in Embodiment 3 of this invention. In the third embodiment of the present invention, a plurality of m 1.45 to 1.65 μm band equally spaced wavelength slots and a plurality of m 1.3 μm band equally spaced wavelength slots are multiplexed by wavelength multiplexing technology. is there. It is an illustration figure of wavelength arrangement | positioning in the conventional optical wavelength multiplexing technique application point-multipoint optical communication system (it abbreviates as a point-multipoint optical communication system hereafter). It is a block diagram of the conventional point-multipoint optical communication system using the wavelength arrangement | positioning shown in FIG.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a point-multipoint optical communication system of the invention will be described with reference to the drawings.
In the point-multipoint optical communication system of the present invention, the center wavelength of the station side device and the center wavelength of the plurality of subscriber side devices are arranged in one wavelength slot, and the wavelength slot widths of the plurality of subscriber side devices are set. It is technically characterized to be arranged wider than the wavelength slot width of the station-side device, and not only lowers the cost of the subscriber-side device, but also in such a basic point in a plurality of point-multipoint optical communication systems. By performing multiplexing based on the configuration, there is also an advantage that the configuration of the wavelength multiplexer / demultiplexer can be simplified.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a point-multipoint optical communication system according to Embodiment 1 of the present invention. A point-multipoint optical communication system 1 in FIG. 1 includes a station-side device 2, n (n is an integer of 2 or more) subscriber-side devices 3 (1) to 3 (n), station-side devices 2 and n. It comprises a star coupler 4 and an optical fiber 5 for connecting the subscriber side devices 3 (1) to 3 (n).

  FIG. 2 is a diagram showing the wavelength arrangement of the point-multipoint optical communication system 1 according to Embodiment 1 of the present invention. In FIG. 2, the equally spaced wavelength slots 21 defined by the wavelength interval Δλd are indicated by broken lines. Further, the equally spaced wavelength slots 21 include a downstream wavelength slot 22 and an upstream wavelength slot 23 obtained by dividing the equally spaced wavelength slot 21.

  A point-multipoint optical communication system having one station side device 2 and a plurality of subscriber side devices 3 (1) to 3 (n) as shown in FIG. I will call it. In such a basic configuration optical communication system, one equally spaced wavelength slot 21 may be arranged. However, as will be described later in the second embodiment, in a plurality of point-multipoint optical communication systems composed of a plurality of basic configuration optical communication systems, it is necessary to arrange a plurality of equally spaced wavelength slots 21, and the names are unified. Therefore, also in the first embodiment, it is referred to as “equally spaced wavelength slot 21”.

  Here, the downlink wavelength slot 22 is a downlink wavelength slot having a wavelength slot width of Δλd1 (corresponding to the first wavelength slot width) formed by dividing the equally-spaced wavelength slot 21, and the station side device 2 to an optical signal to a plurality of subscriber side devices 3 (1) to 3 (n).

  The upstream wavelength slot 23 is an upstream wavelength slot having a wavelength slot width of Δλd2 (corresponding to the second wavelength slot width), which is obtained by dividing the equally spaced wavelength slot 21, and a plurality of subscribers. Assigned to the optical signal from the person side apparatus 3 (1) to 3 (n) to the station side apparatus 2.

  Here, the present invention is characterized in that the relationship between the wavelength slot widths is Δλd = Δλd1 + Δλd2 and Δλd1 ≦ Δλd2.

  In FIG. 2, one downstream signal light 24 is disposed in the downstream wavelength slot 22, and n upstream signal lights 25 (1) to 25 (1) to 25 are disposed in the upstream wavelength slot 23. The case where (n) is arranged is illustrated. Of course, there may be a plurality of downstream signal lights 24 using a wavelength multiplexing technique, and a wavelength multiplexing technique may be used for the upstream signal light 25. FIG. 2 shows, as an example, a case where broadcast communication is applied to downlink communication and time division multiplex communication is applied to uplink communication.

  In a point-multipoint optical communication system 1 that is a basic configuration optical communication system as shown in FIG. 1, a station side device 2, a star coupler 4, and an optical fiber 5 are connected to n subscriber side devices 3 (1) to 3 (1) -3. By sharing in (n), the cost is reduced. Here, the transmission light sources of the station-side device 2 and the n subscriber-side devices 3 (1) to 3 (n) are key devices that occupy a large part of the cost.

  Therefore, when considering the cost reduction of the entire apparatus, the requirements for the transmission light source of the station side apparatus 2 are made stricter, and the requests for the transmission light sources of the n subscriber side apparatuses 3 (1) to 3 (n) are required. It is necessary to relax the conditions. That is, there is an aim to reduce the unit price of the subscriber side apparatus by relaxing the conditions of the plurality of subscriber side apparatuses.

  In particular, the requirement for the wavelength range of the transmission light source is a parameter that determines the cost. Therefore, as shown in FIG. 2, by setting Δλd1 ≦ Δλd2 and making the upstream and downstream wavelength slot ranges asymmetric, the requirements for the wavelength ranges of the n subscriber side devices 3 (1) to 3 (n) are as follows. It can be loosened and the cost can be reduced.

  In the wavelength arrangement shown in FIG. 2, the downstream signal light 24 and the upstream signal light 25 are respectively disposed in separate wavelength slots (downstream wavelength slot 22 and upstream wavelength slot 23). It is also effective for the resistance to reflection by the optical fiber 5 which is a transmission path.

  For example, consider a case where the downstream signal light 24 is reflected in the optical fiber 5 and returns to the transmission side. In this case, when the downstream signal light 24 and the upstream signal light 25 are not arranged in different wavelength slots (that is, arranged in the same wavelength slot), the downstream signal light 24 The crosstalk that occurs between the reflected light and the upstream signal light 25 becomes coherent crosstalk when the wavelengths of the two coincide with each other, causing a significant deterioration in transmission quality.

  On the other hand, in the wavelength arrangement shown in FIG. 2, the downstream signal light 24 and the upstream signal light 25 are disposed in different wavelength slots, so that reflection occurs even in the optical fiber 5 serving as a transmission path. Even in this case, the possibility of coherent crosstalk is zero, and high transmission quality can be maintained.

  As described above, according to the first embodiment, the downlink wavelength slot in which the center wavelength of the station side device is arranged and the downlink wavelength slot in which the center wavelengths of the plurality of subscriber side devices are arranged are set to one, etc. The wavelength slot widths of the plurality of subscriber side devices are allocated wider than the wavelength slot widths of the station side devices. Thereby, it is possible to obtain a point-multipoint optical communication system that enables cost reduction of the subscriber side apparatus.

Embodiment 2. FIG.
FIG. 3 shows that a plurality of m (m is an integer of 2 or more) point-multipoint optical communication systems (1 (1) to 1 (m)) according to the second embodiment of the present invention are multiplexed by wavelength multiplexing. It is a block diagram. That is, the point-multipoint optical communication system of FIG. 3 is the same as the basic configuration optical communication system described in the first embodiment in the common optical fiber 5, the wavelength multiplexer / demultiplexer 6 on the station side, and the transmission path. The wavelength multiplexer / demultiplexer 7 is used to connect m pieces.

  The multi-point optical communication system 1 (k), which is the kth basic configuration optical communication system, includes a station side device 2 (k) and nk units (nk is an integer of 2 or more) subscriber side devices 3 (k, 1) to 3 (k, nk), a star coupler 4 (k) for connecting the station side device 2 (k) and the nk subscriber side devices 3 (k, 1) to 3 (k, nk), optical It comprises a fiber 5, a wavelength side multiplexer / demultiplexer 6 on the station side, and a wavelength multiplexer / demultiplexer 7 in the middle of the transmission path.

  Each of the plural m point-multipoint optical communication systems 1 (1) to 1 (m) is different only in the wavelength slot allocated to the optical communication, and the basic configuration is the same as that described in the first embodiment. And all are equal. The optical fiber 5, the wavelength multiplexer / demultiplexer 6, and the wavelength multiplexer / demultiplexer 7 are shared by each of a plurality of m point-multipoint optical communication systems 1 (1) to 1 (m). Further, the star couplers 4 (1) to 4 (m) may have different characteristics or may be optical couplers having the same characteristics.

  FIG. 4 is a diagram showing the wavelength arrangement of a plurality of m point-multipoint optical communication systems 1 (1) to 1 (m) according to Embodiment 2 of the present invention. In FIG. 4, m equally-spaced wavelength slots 21 (1) to 21 (m) defined by equal wavelength intervals Δλd are indicated by broken lines. Further, in each of the m equally spaced wavelength slots 21 (1) to 21 (m), a downlink wavelength slot formed by dividing the equally spaced wavelength slots 21 (1) to 21 (m). 22 (1) to 22 (m) and upstream wavelength slots 23 (1) to 23 (m) are included, each paired for each basic configuration optical communication system.

  Here, the downstream wavelength slots 22 (1) to 22 (m) are obtained by dividing each of the equally spaced wavelength slots 21 (1) to 21 (m), and the downstream wavelength slots have a wavelength slot width of Δλd1. The wavelength slot is assigned to the optical signal from the station side devices 2 (1) to 2 (m) to each subscriber side device. Further, the upstream wavelength slots 23 (1) to 23 (m) are obtained by dividing the equally spaced wavelength slots 21 (1) to 21 (m), and the upstream wavelength slots having a wavelength slot width of Δλd2. The slot is assigned to an optical signal from each subscriber side device to the station side devices 2 (1) to 2 (m).

  Here, the present invention is characterized in that the relationship between the wavelength slot widths is Δλd = Δλd1 + Δλd2 and Δλd1 ≦ Δλd2.

  Also, one wavelength transmitted from the kth station side apparatus 2 (k) is accommodated in the kth downlink wavelength slot 22 (k). On the other hand, in the k-th upstream wavelength slot 23 (k), nk wavelengths transmitted from the k-th plurality of subscriber-side devices 3 (k, 1) to 3 (k, nk) are present. Be contained.

  The k-th downstream wavelength slot 22 (k) and the k-th upstream wavelength slot 23 (k) are accommodated in the equally-spaced wavelength slot 21 (k) as a pair, and a plurality of m The equally spaced wavelength slots 21 (1) to 21 (m) are multiplexed using a wavelength multiplexing technique.

  Therefore, with the wavelength arrangement as shown in FIG. 4, a plurality of m point-multipoint optical communication systems 1 (1) to 1 (m) can be multiplexed by the wavelength multiplexing technique.

  In a system in which a plurality of m point-multipoint optical communication systems 1 (1) to 1 (m) as shown in FIGS. 3 and 4 are wavelength-multiplexed, as in the basic configuration optical communication system of the first embodiment, By making the upstream and downstream wavelength slot ranges asymmetrical with each of the m, it is possible to relax the requirements for the wavelength ranges of the plurality of subscriber side devices 3. As a result, cost reduction can be realized.

  Further, by adopting the wavelength arrangement as shown in FIG. 4, the wavelength multiplexer / demultiplexer 7 arranged in the middle of the transmission path multiplexes and demultiplexes a plurality of m equally spaced wavelength slots 21 (1) to 21 (m). It only needs to have the function to do. Therefore, the circuit configuration can be greatly simplified and the cost can be reduced compared with the conventional wavelength arrangement (see FIG. 9), which has been complicated by combining a plurality of wavelength multiplexers / demultiplexers and optical couplers. Maintenance management work can be simplified.

  Furthermore, the wavelength arrangement as shown in FIG. 4 is also effective for the resistance to reflection by the optical fiber 5 serving as a transmission line, as in the first embodiment.

  As described above, according to the second embodiment, in a plurality of point-multipoint optical communication systems, multiplexing based on the basic configuration optical communication system in the first embodiment is performed, so that the wavelength multiplexer / demultiplexer The configuration can be simplified. As a result, the entire system can be reduced in cost and simplified maintenance management work.

Embodiment 3 FIG.
FIG. 5 is a configuration diagram in which a plurality of m point-multipoint optical communication systems ((1) to 1 (m)) according to Embodiment 3 of the present invention are multiplexed by wavelength multiplexing. That is, the point-multipoint optical communication system of FIG. 3 is the same as the basic configuration optical communication system described in the first embodiment in the common optical fiber 5, the wavelength multiplexer / demultiplexer 6 on the station side, and the transmission path. The wavelength multiplexer / demultiplexer 7 is used to connect m pieces.

  A multipoint optical communication system 1 (k), which is the kth basic configuration optical communication system, includes a station-side device 2 (k) having a transmission wavelength of 1.45 to 1.65 μm and a transmission wavelength of 1.3 μm. nk subscriber side devices 3 (k, 1) to 3 (k, nk), station side device 2 (k) and nk subscriber side devices 3 (k, 1) to 3 (k, nk) Are connected by a star coupler 4 (k), an optical fiber 5, a recurring wavelength multiplexer / demultiplexer 6a having a revolving characteristic on the station side, and a recurring wavelength multiplexer / demultiplexer 7a having a revolving characteristic in the middle of the transmission path. The

  Compared with the configuration of FIG. 3 according to the second embodiment, the configuration of FIG. 5 according to the third embodiment uses recursive wavelength multiplexer / demultiplexers 6 a and 7 a instead of the wavelength multiplexer / demultiplexers 6 and 7. The point is different.

  Each of the plural m point-multipoint optical communication systems 1 (1) to 1 (m) is different only in the wavelength slot allocated to the optical communication, and the basic configuration is the same as that described in the first embodiment. And all are equal. Further, the optical fiber 5, the recurring wavelength multiplexer / demultiplexer 6a, and the recursive wavelength multiplexer / demultiplexer 6a are shared by each of a plurality of m point-multipoint optical communication systems 1 (1) to 1 (m). ing. Further, the star couplers 4 (1) to 4 (m) may have different characteristics or may be optical couplers having the same characteristics.

  FIG. 6 is a diagram showing the wavelength arrangement of the kth point-multipoint optical communication system 1 (k) in the third embodiment of the present invention. Here, the equidistant wavelength slot 31 (k) is an equidistant wavelength slot defined by an equal wavelength interval Δλd in the 1.45 to 1.65 μm band. The equidistant wavelength slot 31 (k) includes a downstream wavelength slot 34 (k) having a downstream signal light 36 (k).

  The equally spaced wavelength slots 32 (k) are equally spaced wavelength slots defined by equal wavelength intervals Δλd in the 1.3 μm band. The equidistant wavelength slot 32 (k) includes an upstream wavelength slot 35 (k) having upstream signal light 37 (k).

  In the point-multipoint optical communication system 1 (k), since the cyclic wavelength multiplexers / demultiplexers 6a and 7a are used, the equally spaced wavelength slots 31 (k) for the downstream direction in the 1.45 to 1.65 μm band are used. And 1.3 μm band equally spaced wavelength slots 32 (k) for the upstream direction are input and output from the same input / output port, and the equally spaced wavelength slots 31 (k) and the equally spaced wavelength slots 32 (k) just overlap. Can be.

  The equidistant wavelength slot 33 (k) in FIG. 6 is input and output from the same input / output port because the equidistant wavelength slot 31 (k) for the downlink direction and the equidistant wavelength slot 32 (k) for the uplink direction overlap. This is a diagram showing the state.

  Here, the downstream wavelength slot 34 (k) is obtained by dividing the equally spaced wavelength slot 31 (k) for the downstream direction in the 1.45 to 1.65 μm band, and the downstream wavelength slot width is Δλd1. This is a wavelength slot. The upstream wavelength slot 35 (k) is an upstream wavelength slot having a wavelength slot width of Δλd2 formed by dividing the upstream equally spaced wavelength slot 32 (k) in the 1.3 μm band. .

  The downstream wavelength slot 34 (k) and the upstream wavelength slot 35 (k) are input and output from the same input / output port, and are equally spaced, from the wavelength circulation characteristics of the recursive wavelength multiplexers / demultiplexers 6a and 7a. The wavelength slot 33 (k) is disposed as a pair of wavelength slots.

  Here, the present invention is characterized in that the equally spaced wavelength slots 33 (k) are divided so that the relationship between the wavelength slot widths is Δλ = Δλd1 + Δλd2 and Δλd1 <Δλd2.

  Thus, as in the first and second embodiments, by making the upstream and downstream wavelength slot ranges asymmetric, requirements for the wavelength ranges of the plurality of subscriber-side devices 3 can be relaxed and the cost can be reduced. Can be achieved.

  FIG. 7 shows a plurality of m 1.45 to 1.65 μm band equally spaced wavelength slots 31 (1) to 31 (m) and a plurality of m 1.3 μm band equally spaced wavelengths in Embodiment 3 of the present invention. It is a figure at the time of multiplexing slots 32 (1) -32 (m) by the wavelength multiplexing technique.

  Similarly to the one shown in FIG. 6 above, due to the circulation characteristics of the cyclic wavelength multiplexers / demultiplexers 6a and 7a, a plurality of 1.45 to 1.65 μm band equally spaced wavelength slots 31 (1) to 31 ( m) and a plurality of m 1.3 μm band equally-spaced wavelength slots 32 (1) to 32 (m) can overlap each other, and equally-spaced wavelength slots 33 (1) to 33 (33). (M).

  Similarly, the plurality of m downstream wavelength slots 34 (1) to 34 (m) and the plurality of m upstream wavelength slots 35 (1) to 35 (m) are each a plurality of m equally spaced wavelength slots. 33 (1) to 33 (m) are arranged as a pair of components. Here, the present invention is characterized in that the equally spaced wavelength slots 33 (k) are divided so that the relationship between the wavelength slot widths is Δλ = Δλd1 + Δλd2 and Δλd1 <Δλd2.

  Also in the wavelength arrangement shown in FIG. 7, as in the first and second embodiments, by making the upstream and downstream wavelength slot ranges asymmetric, the requirements for the wavelength ranges of the plurality of subscriber side devices 3 are relaxed. It is possible to reduce costs.

  Further, by adopting the wavelength arrangement as shown in FIG. 7, the cyclic wavelength multiplexer / demultiplexer 7a arranged in the middle of the transmission line multiplexes a plurality of m equally spaced wavelength slots 31 (1) to 31 (m), It is only necessary to have a function of demultiplexing, that is, a function of multiplexing and demultiplexing only a plurality of m equally spaced wavelength slots 32 (1) to 32 (m) and 33 (1) to 33 (m). As a result, the circuit configuration can be greatly simplified compared to the conventional wavelength arrangement that had to be combined with multiple wavelength multiplexers / demultiplexers and optical couplers, resulting in lower costs and maintenance management work. Can be simplified.

  As described above, according to the third embodiment, in a plurality of point-multipoint optical communication systems, multiplexing based on the basic configuration optical communication system in the first embodiment is performed using a recurring wavelength multiplexer / demultiplexer. Can be realized. Furthermore, the configuration of the cyclic wavelength multiplexer / demultiplexer can be simplified as in the wavelength multiplexer / demultiplexer of the second embodiment. As a result, the entire system can be reduced in cost and simplified maintenance management work.

Claims (4)

One station-side device and a plurality of subscriber-side devices are connected by an optical network via a wavelength multiplexer / demultiplexer and an optical fiber transmission line, and the one station-side device and the plurality of subscriber-side devices are connected to each other. In a point-multipoint optical communication system in which each outputs an optical signal to the optical network by time division multiplexing or wavelength multiplexing,
The center wavelength of the station side device and the center wavelength of the plurality of subscriber side devices are arranged in one wavelength slot having a wavelength slot width Δλd,
The wavelength slot having the wavelength slot width Δλd is divided into two wavelength slots having a relationship in which the first wavelength slot width Δλd1 and the second wavelength slot width Δλd2 are Δλd1 + Δλd2 = Δλd and Δλd1 ≦ Δλd2. And
The center wavelength of the station side device is arranged in the wavelength slot having the first wavelength slot width Δλd1, and the center of the plurality of subscriber side devices is placed in the wavelength slot having the second wavelength slot width Δλd2. A point-multipoint optical communication system in which wavelengths are arranged. A basic configuration of a point-multipoint optical communication system including one station-side device and a plurality of subscriber-side devices according to claim 1 as a basic configuration optical communication system, wherein a plurality of m (m is an integer of 2 or more) basic configuration In a point-multipoint optical communication system in which an optical communication system is connected via a common wavelength multiplexer / demultiplexer and a common optical fiber transmission line,
The k-th (k is an integer 1 ≦ k ≦ m) basic configuration optical communication system of the plurality m of basic configuration optical communication systems is defined by m equally spaced wavelength slot widths Δλd having equal wavelength intervals Δλd. Output an optical signal using the kth wavelength slot,
A point-multipoint optical communication system in which respective optical signals output from the plurality m of basic configuration optical communication systems are multiplexed using wavelength multiplexing technology. The point-multipoint optical communication system according to claim 2,
The wavelength multiplexer / demultiplexer is a recursive wavelength multiplexer / demultiplexer having a wavelength recirculation characteristic. In the input / output of a plurality of m basic configuration optical communication systems, a downstream optical signal from a station side device and a plurality of subscribers A point-multipoint optical communication system that inputs and outputs an upstream optical signal from a side device from the same input / output port for each basic configuration optical communication system. The point-multipoint optical communication system according to claim 3,
A point-multipoint optical communication system in which a central wavelength of the station side device is arranged in a 1.45 μm to 1.65 μm band, and a central wavelength of the subscriber side device is arranged in a 1.3 μm band.

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