JPH01190037A - Optical transmission system - Google Patents

Abstract

PURPOSE:To constitute plural optical networks based on different transmission control systems without using an optical multiplexer and an optical demultiplexer by providing a common star coupler to apply the optical transmission between the 1st class optical transmitters and the optical transmission between the 2nd class optical transmitters and implementing the optical transmission between the 1st class optical transmitters and optical transmission between the 2nd class optical transmitters independently. CONSTITUTION:A transmission type star coupler 1 outputs an optical signal distributed equally to optical fibers connected to an input section 1a similarly in the case of receiving an optical signal from an output section 1b to that of receiving an optical signal from an input section 1a. The optical signal sent from the 1st class optical transmitters 3, 4 is given to optical transmission sections 6c, 7c of the 2nd class optical transmitters 6, 7. Moreover, the optical signal sent from the 2nd class optical transmitters 6, 7 is given to optical transmission sections 3c, 4c of the 1st class optical transmitters 3, 4. Thus, the independent optical transmission is implemented without giving mutual affect on the 1st class optical network to which the 1st class optical transmitters 3, 4 belong and on the 2nd class optical network to which the 1st class optical transmitters 6, 7 belong.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical transmission system for performing optical transmission between optical transmission devices using a star coupler as a central node.

(Prior art) Figure 3 shows, for example, R, V, SCIIMIDT, Fibe
rnet ■：＾Fiber 0ptic Ether
net'', IEIEE J, 5ELEC?-Al?E
A IN CO? LM, VOL 5AC-1, NO, 5
, NOV, 1983 is a block diagram of an optical network for explaining a conventional optical transmission system. In the figure, l is a transmission type star coupler that receives an optical signal from an optical fiber and transmits the optical signal to a predetermined optical fiber;
1a is an input part of the star coupler 1 that receives an optical signal via an optical fiber, and lb is an output part of the star coupler 1 that transmits an optical signal to the optical fiber. 2゜3.4.5 is a first type optical transmission device, 'lc, 3c, which transmits an optical signal via a transmission type star coupler 1.

4c and 5c are optical transmitting units provided in the optical transmission devices 2.3 and 4.5, respectively, and transmitting optical signals via optical fibers;
d, 3d, 4d, and 5d are optical transmission devices 2.3.4.
5, each of which receives an optical signal via an optical fiber, an optical receiver 2a.

3a, 4a, 5a are first type optical transmission devices 2.3°4.
Uplink optical fibers 2b, 3b, 4b connect the optical transmission units 2c, 3c, 4c, 5c of No. 5 and the input portion 1a of the transmission type star coupler 1, respectively.

5b is a downlink optical fiber that connects the optical receiving sections 2d, 3d, 4d, and 5d of each of the first type optical transmission devices 2.3.4.5 and the output section 1b of the transmission type star coupler 1, respectively. .

FIG. 4 is a perspective view showing the configuration of the transmission type star coupler 1 shown in FIG. 3. In the figure, 1a is an input section to which an optical fiber is connected and receives the transmitted optical signal, lb is an output section to which the optical fiber is connected and transmits the optical signal received at the input section 1a, and 1c is the input section 1a and the output section. This is a slab-type mixer that is installed between the 1b and 1b and distributes optical signals.

Next, the operation will be explained. The optical signal output from the optical transmitter 2c of the first type optical transmission device 2 is input to the input section 1a of the transmission star coupler 1 via the uplink optical fiber 2a. In the transmission type star coupler l, an optical signal inputted from an input part 1a propagates to an output part 1b in a slab mixer 1c while being subjected to multiple reflections, and then passes through optical fibers 2b, 3b, Distribute to 4b and 5b. The optical signals outputted from the optical fibers 2b, 3b, 4b, and 5b are received by each optical receiver 2d, 3d, 4d, and 5d of the first type optical transmission device 2, 3°4.5. Other type 1 optical transmission equipment 3.4.5° is also type 1 optical transmission equipment 1
Performs the same operation as . Type 1 optical transmission devices 2.3, 4
．． Since 5 shares the transmission star coupler L, burst optical transmission methods such as TDMA (time division multiple access multiple access method) and C5MA/CD (carrier detection multiple access method with collision detection function) can be used as the transmission control method. Applicable.

[Problem to be solved by the invention]

Since the conventional optical transmission system is configured as described above, the first type optical transmission device 2. connected to the transmission type star coupler l. 3. 4. 5 must be composed of one transmission equipment group (optical network) based on a common transmission control method. Therefore, the transmission equipment group based on different transmission control methods is the transmission type star coupler 1 and optical 7 fibers 2a, 2b. ,
3a, 3b.

It was necessary to configure 4a, 4b, 5a, and 5b separately, or to configure a transmission space for performing optical transmission by optical wavelength multiplexing using an optical multiplexer and an optical demultiplexer. As described above, the conventional optical transmission system has a problem in that when a plurality of optical networks based on different transmission control systems are configured, the configuration becomes complicated and the cost increases.

This invention was made to solve the above-mentioned problems, and it is possible to create optical networks based on different transmission control methods using a common transmission star coupler without using optical multiplexers and optical demultiplexers. It is an object of the present invention to provide an optical transmission system that can be configured with a plurality of optical transmission systems and can be realized at low cost.

[Means to solve the problem]

The optical transmission system according to the present invention uses an optical fiber 3a.

An optical transmitter 3c that transmits an optical signal via 4a.

4C and a first type optical transmission device 3 having optical receivers 3d and 4d that receive optical signals via optical fibers 3b and 4b.
．． 4, a second type of optical transmission having optical transmitters 6c, 7c that transmit optical signals via optical fibers 6b, 7b, and optical receivers 6d, 7d that receive optical signals via optical fibers 5a, 7a. A plurality of devices 6 and 7 are provided respectively, and optical transmission between the first type optical transmission devices 3 and 4 and the second type optical transmission device 6 are provided.
, 7, each optical fiber 3a
, 4a, 3b, 4b, 6a, 7a, 6b.

7b, and includes a common star coupler 1 that connects the first type optical transmission devices 3 and 4, and the second type optical transmission device 6.
, 7 are performed independently.

[Effect]

For example, an optical signal transmitted from the optical transmitter 3c of the first type optical transmission device 3 passes through the optical fiber 3a, the star coupler l, and the optical fiber 4b to the first type optical transmission device i! It is received by the optical receiver 4d of No. 4. The light 4g transmitted from the optical transmitter 6c of the second type optical transmission device 6 is transmitted through the optical fiber 6b,
The signal is received by the optical receiver 7d of the second type optical transmission device 7 via the star coupler l and the optical fiber 7a. In this way, the transmission of optical signals between the first type optical transmission devices 3 and 4 and the transmission of optical signals between the first type optical transmission devices 3 and 4,
Transmission of optical signals between the different optical transmission devices 6 and 7 is performed independently through the common star coupler 1 for both devices.

[Embodiments of the invention]

FIG. 1 is a block diagram of an optical network for explaining an optical transmission system according to an embodiment of the present invention. Components in FIG. 1 that correspond to those shown in FIG. 3 are given the same reference numerals, and their explanations will be omitted. In Figure 1,
6.7 is a second type optical transmission device, and belongs to a second type optical network different from the first type optical network to which the first type optical transmission device 3.4 belongs. Reference numeral 6c is an optical transmitting unit that is included in the second type of optical transmission device 6 and transmits an optical signal via an optical fiber, and 6d is also included in the second type of optical transmission device 6 and receives an optical signal via the optical fiber. optical receiver, 7c
Reference numeral 7d is an optical transmitter that is provided in the second type optical transmission device 7 and transmits an optical signal via an optical fiber, and 7d is also provided in the second type optical transmission device 7 and receives an optical signal via the optical fiber. An optical receiving section 6b is an optical transmitting section 6 of the second type optical transmission device 6
An uplink optical fiber 7b connects C and the output section 1b of the pass-through star coupler l, and 7b connects the optical transmission section 7C of the second type optical transmission device 7 and the output section 1b of the pass-through star coupler l. The uplink optical fiber 6a is connected to the optical receiving section 6d of the second type optical transmission device 6 and the input section l of the pass-through star coupler 1.
7a is a downlink optical fiber that connects the optical receiving section 7d of the second type optical transmission device 7 and the input section 1a of the pass-through star coupler 1.

Also, 3c,, 4C+ l 6C+ l 7c+
3d+, 4d+, 6d+, and 7d+ are light emitting elements provided in the optical transmitters 3c, 4c, 6c, and 7c, and optical receivers 3d.

4d, 6d, and 7d.

Figure 2 is a graph showing the spectral sensitivity characteristics of various photodiodes, in which 8 is a Si photodiode and 9 is an I photodiode.
It is a spectral sensitivity characteristic curve of an nGaAs photodiode.

Next, the operation of the embodiment of the present invention will be explained.

The light emitting elements 3C1 and 4C1 of the optical transmission units 3C and 4C of the first type optical transmission devices 3 and 4 also have a second type optical transmission device 6.
and 7, light emitting elements 6c+ and 7 of optical transmitters 6C and 7C.
A case will be described in which a light emitting diode that emits light of the same wavelength is used for c+.

Optical transmission between the first type optical transmission devices 3 and 4 is performed in the same manner as in the conventional example. Even when an optical signal is input from the output section 1b, the transmission type star coupler 1 equally distributes the optical signal to the optical fiber connected to the input section la in the same manner as when the optical signal is input from the input section 1a. It has reversibility when it comes to output. Optical transmission between the second type optical transmission devices 6 and 7 is as follows:
The inside of the transmission type star coupler l is connected to the first type optical transmission device 3, 4.
The optical transmission is performed on the same principle as the optical transmission between the first type optical transmission devices 3 and 4, except that the optical signal propagates in the opposite direction. The transmission type star coupler l is structurally connected to the uplink optical fiber 3a to the input section 1a.

No optical signals are coupled between 4a, 6a, and 7a.

Downlink optical fiber 3b similarly connected to output section 1b
, 4b, 6b, and 7b. Therefore, the optical signals transmitted from the first type optical transmission devices 3 and 4 are not received by the second type optical transmission devices 5 and 6. Not in principle.

In the optical transmission system according to this embodiment, the optical signals transmitted from the first type optical transmission devices 3 and 4 are input to the optical transmitters 6C and 7C of the second type optical transmission devices 6 and 7. Further, the optical signals transmitted from the second type optical transmission devices 6 and 7 are transmitted to the optical transmitting units 3C and 4 of the first type optical transmission devices 3 and 4.
It is input to C. However, each optical transmitter 3c, 4c, 6c
, 7c does not affect the modulation operation even if an optical signal is injected from the outside.

As described above, in the optical transmission system of the above embodiment, the first type optical network to which the first type optical transmission device 3.4 belongs and the second type optical network to which the second type optical transmission device 6.7 belongs. can perform optical transmission independently without influencing each other. Furthermore, in the above embodiment, the light emitting element 6C1
When using a laser diode as +7 CB, the modulation operation of the laser diode becomes unstable with respect to externally injected light of the same wavelength, so it is necessary to set the wavelength of the injected light to be different from the oscillation wavelength of the laser diode. be. The first type of optical transmission device! ! If a laser diode is used in 3.4, the second type optical transmission devices 6 and 7 use a laser diode that outputs an optical signal with a wavelength different from the oscillation wavelength of the laser diode in the first type optical transmission device 3.4. Or it is necessary to use light emitting diodes.

An actual optical fiber transmission line has connection points such as optical connectors, and a portion of the optical signal is reflected at the connection points.

The return loss of optical connectors is 13dB to 30d per point.
It is B. For example, if an optical signal transmitted from the first type optical transmission device 3 is reflected at a connection point in the middle of the downlink optical fiber 3b, the reflected light is input from the output part 1b of the transmission star coupler 1, and Similar to the optical signals transmitted from the second type optical transmission devices 6 and 7, the transmission type star coupler 1 equally distributes the optical signals to the uplink optical fibers 3a, 4a, 6a, and 7a, and the light of the second type optical transmission devices 6 and 7 Receiving parts 6d and 7d
received at. Normally, the reflection attenuation 1 of light is small and transmission between the second type optical transmission devices 6 and 7 is not hindered by reflected light.

As shown in FIG. 2, the spectral sensitivity characteristic 8 of the Si photodiode and the spectral sensitivity characteristic 9 of the InGaAs photodiode differ in the wavelength range in which they are sensitive. The first type of optical transmission devices 3 and 4 transmit optical signals of 0.8 μm using St Fort diodes or Si avalanche photodiodes, and the second type of optical transmission devices 6 and 7 use InGaAs photodiodes or InGaAs avalanche photodiodes. When transmitting a 1.3 μm optical signal using a diode,
Even if reflected light occurs at the connection point, the light receiving element 3d.

4 (Due to the difference in spectral sensitivity characteristics of 1+, 6 d+, and 7 d+, even if an optical signal is input, it is not converted to an electrical signal. Optical transmission between devices 6 and 7 is not hindered.

According to the above embodiment, since the optical signal propagates in only one direction within the transmission star coupler l, the first type of optical transmission device 3.
When the optical signal of 4 and the optical signal of the second type optical transmission device 6.7 are propagated in opposite directions in the transmission type star coupler l, the optical signals are input to the optical receiver of the other optical transmission device. This allows two independent optical networks to be constructed. In addition, optical signals from optical transmitting devices belonging to other optical networks are input to the optical transmitting section, but in particular, a laser diode is used for the light emitting element of the optical transmitting device belonging to one optical network, and the other optical By using laser diodes or light emitting diodes that emit light of different wavelengths as light emitting elements of optical transmission devices belonging to a network, the influence of optical signals on each other can be eliminated. In addition, Si
By using a photodiode and an InGaAs photodiode, respectively, and using optical signals of different wavelengths, the degree of separation between the two optical networks is improved.

In the above embodiment, the transmission control method is T.
Although the case where a burst optical transmission method such as DMA or C3MA/CD is used has been described, the present invention may also be applied to a broadcast transmission system using a continuous transmission method.

In addition, the input section 1a and the output section 1b of the transmission type star coupler 1
The name is for convenience and is the first type optical transmission device 3.4.
Similar effects can be obtained even if the connections of the second type optical transmission devices 6 and 7 are reversed.

(Effects of the Invention) As described above, according to the present invention, a plurality of first type optical transmission devices and a plurality of second type optical transmission devices are provided, and optical transmission between the first type optical transmission devices and It is equipped with a common star coupler for performing optical transmission between two types of optical transmission devices, and the first
Since optical transmission between the first type optical transmission devices and optical transmission between the second type optical transmission devices are performed independently, different transmission control methods can be used without using optical multiplexers and optical demultiplexers. It is possible to construct a plurality of optical networks based on the above, and to provide an inexpensive optical network.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical network for explaining an optical transmission system according to an embodiment of the present invention, FIG. 2 is a graph showing spectral sensitivity characteristics of various photodiodes in this embodiment, and FIG. 3 4 is a block diagram of an optical network for explaining a conventional optical transmission system, and FIG. 4 is a perspective view showing the configuration of a transmission type star coupler. DESCRIPTION OF SYMBOLS 1... Transmissive star coupler, 3.4... 1st type optical transmission device, 6, 7... 2nd type optical transmission device, 3a, 3
b, 4a, 4b, 6a, 6b. 1a, 1b...-optical fibers, 3c, 4c, 6c. 7C... Optical transmitter, 3d, 4d, 6d, 7d... Optical receiver, 3C+, 4c+, 5c,, 7c+... Light emitting element, 3dl, 4d+, 6dl, 7dl...
Light receiving element. Agent: Masuo Oiwa (and 2 others)
Z 3a, 3b, Q4b, 6a, 6b, 7a, 7)) --
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忰3djun, package, 7 (1---L missing bond 3c+, 4ct, 6cI7c, --ichiki 94shi 3dI
Qh, mark +, 7d+--Ikke 0 sho No. 29 1 length λ [7-] Figure 3 Procedural amendment (voluntary) 1. Indication of the incident Patent application No. 1983-014124 3,
Representative of the person making the amendment Moriya Shiki 5 Column for detailed explanation of the invention to be amended. G. Contents of the amendment (1) On page 4, line 10 of the specification, the phrase "time division multiplex multiple access system" is amended to read "time division multiplex multiple access system." (2) In the same book, page 8, line 2, line 4, line 6 to line 7, and line 9, "through-type star coupler l" is replaced with "through-type star coupler 1". and correct it. (3) In the same book, page 9, line 1, ``in r3c and 4c,'' is corrected to ``in r3c and 4c,''. that's all

Claims (1)

[Claims] A first comprising an optical transmitter that transmits an optical signal via an optical fiber and an optical receiver that receives an optical signal via the optical fiber.
A plurality of optical transmission devices of the second type and a plurality of optical transmission devices of the second type each having an optical transmission unit that transmits an optical signal via an optical fiber and an optical reception unit that receives an optical signal via the optical fiber are provided, Optical transmission between the first type optical transmission devices and the second type
A common star coupler is provided for connecting each of the above-mentioned optical fibers in order to perform optical transmission between the above-mentioned first-type optical transmission devices, and optical transmission between the above-mentioned first-type optical transmission devices and the second-type optical transmission device. An optical transmission method characterized by performing optical transmission between the two independently.