JPH03226137A - Optical wavelength split multiple communication system and communication network - Google Patents

Abstract

PURPOSE:To minimize the number of wavelength variable transmission light sources provided to a transmission station by dividing a wavelength band of a transmission line into N, allowing plural reception stations to receive an optical signal for each of N wavelength bands and specifying a reception station depending on the combination of the wavelength of the optical signal in the N wavelength bands. CONSTITUTION:Transmission signals sent in a form of a data signal light with a 1st optical wavelength lambdak(1<=k<=32, k is an integer) in an operating wavelength band from transmission stations 11, 12,..., 1N and of a clock signal light with an optical wavelength lambda1 (33<=l<=64, l is an integer) in a 2nd operating wavelength band are multiplexed by a star coupler 1 and power is branched equally in reception stations 21, 22,..., 2N. The data signal and the clock signal are sent simultaneously only to a reception circuit of a reception station having a filter whose passing optical wavelength in the 1st operating wavelength band is lambdak and whose passing optical wavelength in the 1st operating wavelength band is lambdal among the reception stations 21, 22,..., 2N and the transmission signal is selectively sent to the reception station only. Thus, number of wavelength variable transmission light sources of the transmission stations is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical communication network, and more particularly to an optical wavelength division multiplexing communication network used for ultra-high speed local area networks between computers.

(Prior art) A communication network suitable for an ultra-high-speed local area network includes multiple transmitting stations that can change the wavelength of optical signals to be transmitted, and wavelength division multiplexing of all optical signals transmitted by each of the multiple transmitting stations. There is an optical wavelength division multiplexing communication network that consists of a transmission line that receives optical signals of specific fixed wavelengths, and multiple receiving stations that receive only optical signals of specific fixed wavelengths, and that identifies receiving stations by the wavelength of the optical signal transmitted by the transmitting station. . FIG. 3 is a block diagram showing the configuration of a conventional optical wavelength division multiplexing communication network, and the conventional optical wavelength division multiplexing communication network will be described using this diagram. IEEE Journal on Selected Areas in Communications (IEEE JOll)
NAI ON 5ELECTEI) AREAS
lNC0)4HUNICAT1ONS) Volume 6 No. 9 (
1988), pages 1500-1510, each receiving station 21.22. . . 2M is equipped with bandpass optical wavelength filters 161° 162, . Tunable semiconductor lasers 141 and 142° that can change the wavelength of the light emitted within the wavelength range that includes all of the optical signals received by the laser.
..., 14M is equipped, each transmitting station 11, 12°...
・The destination of transmission is specified by making the wavelength of the optical signal transmitted by , 1M equal to the passing wavelength of a band-pass optical wavelength filter provided at the receiving station, which is the destination of transmission. Table 2 shows an example of combinations of transmitting optical wavelengths and receiving station numbers in this conventional optical wavelength division multiplexing communication network. As is clear from Table 2, in this conventional optical wavelength division multiplexing communication network, the number of transmitting stations and receiving stations are both 32.

Table 2 (Problems to be Solved by the Invention) However, in a conventional optical wavelength division multiplexing communication network, the same number of optical signals with different wavelengths as the number of receiving stations are required to propagate through the transmission path in the communication network. The number of optical signals having different wavelengths is limited by the wavelength tunable range of the wavelength tunable laser provided at the transmitting station, and as a result, the number of receiving stations in the network is limited. for example,
In the conventional optical wavelength division multiplexing communication network described above, the wavelength tunable range of the wavelength tunable distributed reflection semiconductor laser used as the wavelength tunable light source is approximately 3nl, and the wavelength interval of each optical signal propagating through the transmission path in the communication network is 01n1, the number of receiving stations was limited to 32. However, since local area networks such as those between computers require hundreds of receiving stations, hundreds of optical signals with different wavelengths are also required to propagate through transmission paths in communication networks. In order to expand the wavelength tunable range of the optical signal transmitted by the transmitting station, the wavelength tunable range of the transmission light source required for the network communication network configuration greatly exceeds the wavelength tunable range of the emitted light from a single semiconductor laser. In this case, each transmitting station should be equipped with a plurality of wavelength tunable distributed reflection semiconductor lasers with different wavelength tunable ranges.
Then, the number of lasers at each transmitting station becomes large,
There was a fear that the transmitter would be expensive and the multiplexing loss would be large. For example, when configuring a transmitter capable of transmitting optical signals to each of 1024 receiving stations using a wavelength tunable distributed reflection semiconductor laser with a wavelength tunable range capable of emitting 32 lights of different wavelengths and a 2x2 optical coupler. ,
The number of lasers per transmitting station is 32, and the combining loss is 1.
It ends up being about 5 dB.

Therefore, the present invention identifies a receiving station based on the wavelength of an optical signal transmitted by a transmitting station, and the transmitting station uses a large-scale optical wavelength division multiplexing communication network to transmit optical signals to each of a large number of receiving stations. The objective is to minimize the number of wavelength tunable transmission light sources provided in the station.

<Means for Solving the Problems> The optical wavelength division multiplexing communication system of the present invention includes a plurality of transmitting stations that can freely change the wavelength of optical signals to be transmitted, and a plurality of optical signals output by the plurality of transmitting stations. It consists of a transmission path for wavelength multiplexing and transmission, and a plurality of receiving stations that receive an optical wavelength multiplexed signal propagating through the transmission path and extract and receive an optical signal of a specific wavelength from the optical wavelength multiplexed signal. , in an optical wavelength division multiplexing communication network in which a receiving station is identified by the wavelength of an optical signal to be transmitted, the wavelength band of the transmission path is divided into N parts (N is a natural number of 2 or more), and the plurality of transmitting stations Each of the plurality of receiving stations transmits an optical signal in each of the N wavelength bands, and each of the plurality of receiving stations receives the optical signal in each of the N wavelength bands. It is characterized by specifying.

Further, the optical wavelength division multiplexing communication network of the present invention includes a plurality of transmitting stations that can freely change the wavelength of optical signals to be transmitted, and a transmission system that optically wavelength-multiplexes and transmits the optical signals output by the plurality of transmitting stations. It consists of a transmission line and a plurality of receiving stations that receive an optical wavelength multiplexed signal propagating on the transmission line and extract and receive an optical signal of a specific wavelength from the optical wavelength multiplexed signal.The wavelength of the optical signal to be transmitted is In an optical wavelength division multiplexing communication network in which a receiving station is identified by N wavelength tunable light sources each corresponding to the N transmission wavelength bands that can be freely changed;
The plurality of receiving stations have N wavelength selection means each corresponding to the N transmission wavelength bands for selecting one or more optical signals from the optical wavelength multiplexed signal, and the plurality of receiving stations The N wavelengths selected by the N wavelength selection means, respectively.
The combination of wavelengths of optical signals in each transmission wavelength band is characterized by being different.

(Function) Since the combination of selected optical signals for each wavelength band of the wavelength selection means is different among all the receiving stations constituting the communication network, the wavelength of the signal light in each wavelength band of each transmitting station is different from the wavelength of the signal light in each wavelength band of each transmitting station. By making the wavelength equal to the wavelength of the optical signal selected in each wavelength band of the station, the transmission destination can be specified.

(Example) Next, the present invention will be described with reference to the drawings and tables. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. This embodiment is an optical wavelength division multiplexing local network with a number of 1024 stations in which a receiving station is identified only by wavelength information of an optical signal transmitted by a transmitting station. In the area network, the number of wavelength bands used for optical signals in the transmission path is two, and the number of optical signals that can be wavelength division multiplexed within one wavelength band used is 32.

Table 1 is a correspondence table between the receiving station number of each receiving station in this embodiment and the wavelength passed by the band-pass optical filter. As shown in Table 1, the first used wavelength band has optical signals of wavelengths λ1 to λ3□, and the second used wavelength band has optical signals of wavelengths λS to λ6.
．． Optical signals of each wavelength are defined respectively. A data signal is simultaneously transmitted using a first used wavelength band, and a clock signal is simultaneously transmitted using a second used wavelength band. Each receiving station includes a band-pass optical wavelength filter that selectively passes an optical signal of wavelength λ, ~λ32, and wavelength λ33~.
A band-pass optical wavelength filter that selectively passes any one of the optical signals of λ64 is provided.

On the fir axis of Table 1, read the wavelength of light passing in the first used wavelength band corresponding to the receiving station number, and on the horizontal axis of the same table, read the wavelength of passing light in the second used wavelength band corresponding to the receiving station number. I can do it. For example, in the receiving station with receiving station number 68, the wavelength λ4 is used in the first used wavelength band, and the wavelength ^3 . . . is used in the second used wavelength band. pass through each. That is, when specifying the receiving station with the receiving station number 68 as the transmission destination, the data signal is transmitted at the wavelength λ4, and the data signal is transmitted at the wavelength λ,.

to transmit the clock signal.

In the example shown in Table 1 and Figure 1, 1 is 2048X 204
8-light Katsupura, 11, 12. ..., IN is the transmitting station, 2
1.22. ..., 2N is a receiving station.

Transmitting stations 11, 12. ..., IN, 31°32
, ..., 3N are all transmitting circuits, and 41°42
,...,4N and 51,52. ... 5N are all distributed reflection semiconductor lasers with a 1°3 μm band phase control region. This laser 41.42. ...The wavelength variable range of the output light of 4N is wavelength λ1°λ2. ..., λ
The first wavelength band used includes 32 and 5 lasers 5
1,52. . . , the wavelength variable range of the output light of 5N is the wavelength λ33. λ, 4. . . . includes a second used wavelength band including λ64. Therefore, the laser 41,4
2. . . , 4N to transmit data signals, and the lasers 51, 52 . ...The clock signal is transmitted using 5N.

Receiving stations 21, 22. ..., 2N receiving station numbers are 1, 2, . . . , 2N, respectively. ..., 1024. Receiving station 21゜2
2,..., 2N, 81.82. . . , 8N are receiving circuits each including a p1n photodiode as a light receiving element. 61.62. ..., 6N and 71.7
2. ..., 7N are all distributed feedback type semiconductor laser filters. The wavelengths of light passing through the filters 61, 62°, . . . , 6N are λ1. λ2. ...λ32.

In addition, filters 71, 72 . ...7N passing light wavelengths are λ, 3. ^34+ ”'λ64.

FIG. 2 shows receiving stations 21, 22. . . , is a diagram showing the configuration of 2N. The data signal light with the wavelength λ that has passed through the distributed feedback semiconductor laser filter 91 whose passing wavelength is one of the wavelengths λk from the wavelengths λ〉 to λ3□ in the first used wavelength band is photoelectrically converted by the pin photodiode 93. After being further amplified by an amplifier 95, it is input to a data input terminal 98 of a D-flip-flop 97. On the other hand, the second
Any wavelength of λ, 3 to λ64, which is the wavelength band used for
Distributed feedback semiconductor laser filter 9 with a passing wavelength of
The clock signal light having the wavelength λ1 that has passed through the D-type flip-flop 97 is photoelectrically converted by the pin photodiode 94 and further amplified by the amplifier 96, and then input to the clock input terminal 99 of the D-flip-flop 97. By using the D-flip flop 97, both the data signal light with the wavelength λ and the clock signal light with the wavelength λ are simultaneously transmitted to the receiving station 21.
Only when input to ~2N, output terminal 1 of positive phase and negative phase
It becomes possible to obtain output from 00°101.

Transmitting stations 11, 12 . in FIG. ..., optical wavelength λk in the first used wavelength band from IN (1≦to≦32
.
The waves are multiplexed by each receiving station 21, 22 . ..., 2N
The power is divided evenly. Receiving stations 21, 22. ...
, 2N, the wavelength of the light passing through the filter having the light passing wavelength in the first used wavelength band is λ, and the wavelength of the light passing through the filter having the passing light wavelength in the second used wavelength band is λ
, the data signal and the clock signal are simultaneously transmitted only to the receiving circuit of the receiving station, and the transmission signal is selectively transmitted only to the receiving station.

With the configuration described above, a wavelength tunable distributed reflection type semiconductor laser having a wavelength tunable range capable of emitting light having 32 mutually different wavelengths is used to identify a receiving station using only wavelength information of an optical signal transmitted by a transmitting station. When configuring a transmitter that can transmit optical signals to each receiving station in a division multiplex communication network, transmitting station 1
The number of lasers per station is 2, and the multiplexing loss is equivalently 3.
It can be reduced to about dB.

In this embodiment, the number of communication wavelengths in the filter of the receiving station is one for each used wavelength band, but the combinations of passing wavelengths for each used wavelength band are different in all the receiving stations making up the communication network. As long as the conditions are met, there may be a plurality of wavelength bands for each used wavelength band.

Further, in this embodiment, the number of wavelength bands used is two, but the number of wavelength bands used may be three or more, for example,
If the number of wavelength bands used is 3, a station that uses a wavelength tunable laser with a wavelength tunable range that can emit light of 10 different wavelengths to identify the receiving station only by the wavelength information of the optical signal transmitted by the transmitting station. An optical wavelength division multiplexing communication network with 1000 wavelength division multiplexing devices can be constructed.

(Effects of the Invention) As explained in detail above, according to the present invention, the number of wavelength tunable transmitting light sources whose wavelength tunable range of emitted light is limited is minimized, and the light that passes through each receiving station is Optical signals transmitted from each transmitting station are equipped with band-pass optical wavelength filters with different wavelengths, and each transmitting station is equipped with a wavelength-tunable semiconductor laser that can be tuned in the wavelength range of all optical signals received at all receiving stations. It is possible to construct a large-scale optical wavelength division multiplexing communication network in which the transmission destination is specified by making the wavelength of the transmission destination equal to the passing wavelength of the transmission destination receiving station.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a receiving station in the optical wavelength division multiplexing communication network of the present invention, and FIG. 3 is a diagram showing the configuration of a receiving station in the optical wavelength division multiplexing communication network of the present invention. FIG. 2 is a block diagram showing the configuration of a network. 1...2048x 2048 Star Katsupura, 2...
・32x32 star cutlet pla, 11,12. ..., L
M, IN... transmitting station, 21, 22. ..., 2M, 2
N...receiving station, 31. 32. ..., 3N, 131
, 132°..., 13M... Transmission circuit, 41, 42
．． ..., 4N51.52. ..., 5N... distributed reflection semiconductor laser with phase control region, 61, 62. ...
, 6N, 71°72,..., 7N, 91.92・
...Distributed feedback semiconductor laser filter, 81.82...
・, 8N, 181182, ..., 18M... Receiving circuit, 93.94... Photodiode, 95.96.
...Amplifier, 97...D flip-flop, 98...
・Data input terminal, 99...Clock input terminal, 10
0... Positive phase output terminal, 101... Negative phase output terminal, 1
41,142. ..., 14M... wavelength tunable semiconductor laser, 161,162..., 16M... bandpass wavelength filter, 191.192... optical fiber.

Claims (2)

[Claims] (1) A plurality of transmitting stations that can freely change the wavelength of optical signals to be transmitted, a transmission line that optically wavelength multiplexes and transmits the optical signals output by the plurality of transmitting stations, and light that propagates through the transmission line. Optical wavelength division multiplexing consists of multiple receiving stations that receive a wavelength multiplexed signal and extract and receive an optical signal of a specific wavelength from the optical wavelength multiplexed signal, and the receiving station is identified by the wavelength of the optical signal to be transmitted. In the communication network, the wavelength band of the transmission path is divided into N parts (N is a natural number of 2 or more), each of the plurality of transmitting stations transmits an optical signal for each of the N wavelength bands, and the plurality of transmission stations transmits an optical signal for each of the N wavelength bands. An optical wavelength division multiplexing communication system characterized in that each receiving station receives an optical signal in each of N wavelength bands, and the receiving station is identified by a combination of wavelengths of the optical signals in the N wavelength bands. (2) A plurality of transmitting stations that can freely change the wavelength of optical signals to be transmitted, a transmission line that wavelength-multiplexes and transmits the optical signals output by the plurality of transmitting stations, and light that propagates through the transmission line. Optical wavelength division multiplexing consists of multiple receiving stations that receive a wavelength multiplexed signal and extract and receive an optical signal of a specific wavelength from the optical wavelength multiplexed signal, and the receiving station is identified by the wavelength of the optical signal to be transmitted. In the communication network, the transmission path is divided into N parts (N is a natural number of 2 or more) with respect to the transmission wavelength band, and the plurality of transmitting stations can freely change the wavelength of the emitted light. It has N wavelength tunable light sources each corresponding to a wavelength band,
The plurality of receiving stations each have N wavelength selection means corresponding to the N transmission wavelength bands for selecting one or more optical signals from the optical wavelength multiplexed signal, and each of the plurality of receiving stations The N wavelengths selected by the N wavelength selection means.
An optical wavelength division multiplexing communication network characterized in that the combinations of wavelengths of optical signals in different transmission wavelength bands are different.