GB2268848A - Transmission active fiber-optic star coupler for a network system - Google Patents
Transmission active fiber-optic star coupler for a network system Download PDFInfo
- Publication number
- GB2268848A GB2268848A GB9214805A GB9214805A GB2268848A GB 2268848 A GB2268848 A GB 2268848A GB 9214805 A GB9214805 A GB 9214805A GB 9214805 A GB9214805 A GB 9214805A GB 2268848 A GB2268848 A GB 2268848A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fiber
- coupler
- optic
- star coupler
- optical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/009—Topology aspects
- H04Q2011/0094—Star
Abstract
A fiber-optic star coupler is configured by associating fiber amplifiers and passive fiber-optic star couplers to form a transmissive N*N active fiber-optic star coupler. The star coupler mainly contains 4*4 active fiber-optic star couplers and 2*2 3dB passive fiber-optic couplers acting as basic optical elements, wherein each of the 4*4 active fiber-optic star couplers is composed of six units of 2*2 3dB (or two units of 4*1 optical coupler), a dichroic coupler 27, an optical amplified fiber 28, and an optical isolator 29. By using a plurality of 4*4 active fiber-optic star couplers and 2*2 3dB passive fiber-optic coupler, it is possible to configure any desired configuration of transmissive N*N active fiber-optic star coupler. The number N may be any integral power of 2. The coupler in such a configuration uses less pumping sources and associated optical elements, and has the advantages of compensating the splitting loss and excess loss of the coupler, and therefore making it possible to expand the amount of connected terminals. As a result, the cost of the coupler may be reduced by 60% comparing to that of the prior art. In addition, the coupler can adapt to various pumping sources with different wavelength to meet the real demands and conditions of the network system. <IMAGE>
Description
SPECIFICATION
Transmissive Active Fiber-Optic Star Coupler for a
Network system
The present invention relates to an optical fiber star coupler, and more particularly to a transmissive active fiber-optic star coupler for a network system.
It is well-known that a star network system is widely used in an optical network system. The star network system are generally equipped with multiple transmitting ports and receiving ports capable of connecting with data terminals, and therefore the informations in the form of light signals may be transmitted from transmitting ports to receiving ports through optical fibers. It is possible to expand additional terminals to the network system without changing or modifying the physical configuration thereof. One of the advantages of such a star network system is that in case a branch of the fiber-optic is broken, only the terminal coupled thereto will be disconnected from the network system while the other terminals still work normally and correctly. Therefore, the star network is particularly suitable to the network communication systems equipped with multiple data terminals.In the prior art, a N*N transmissive passive star coupler is usually used to act as an important coupling device for transmitting and distributing the signal sources to all receivers.
Theoreticallv, the conventional passive fiber-optic star coupler is capable of transmitting and distributing the signal sources from transmitting ports to all terminals in the network. However, the number of connected terminals is still limited in practice. In other words, when the number of connected terminals is getting more, the transmitted signals will be correspondingly attenuated in amplitude during transmission due to splitting loss and total excess loss caused by the coupler. The splitting loss is defined as 10 log (N), and the total excess loss is defined as log (N) * 10 log(L).
2
The symbol L in the definition represents the excess loss of a 2*2 3dB fiber-optic coupler. It is obvious that the conventional passive fiber-optic star coupler can only support a limited number of communication ports in practice due to the fact of the attenuation of transmitted signals. This is the most important drawback found in the conventional star coupler.
With the development of the fiber-optic technique nowadays, high gain optical amplifiers with high output power is available to compensate the splitting loss and the excess loss of the passive fiber-optic coupler in the prior art. Generally, the high gain optical amplifiers may be placed directlv after the semiconductor laser of the transmitting port, acting as an optical power amplifier to enhance the intensity of the light signals being transmitted. Alternatively, the optical amplifier mav be arranged in front of the receiving port, acting as an optical preamplifier to increase the receiving sensitivity of the receiving port. Both of these arrangements in the prior art may probably compensate the transmission loss for the passive fiber-optic star coupler. However, it is necessary to arrange an optical amplifier to each branch of the communication ports of the network.For example, it requires N units of optical amplifier for forming a N*N star network system. Each of the optical amplifiers is generally composed of an optical fiber, a pumping source, a dichroic fiber-optic coupler, and an optical isolator. Obviously, the configuration with optical amplifier in each port is relatively complicated and expensive, and therefore it is not economical for practical use.
To overcome the aforementioned drawbacks and problems found in the prior art, the primary object of the present invention is to provide a transmissive active fiber-optic star coupler for a network system. Comparing to the prior art, the coupler of the present invention not only compensates the splitting loss and total excess loss effectivelv, but also requires less numbers of optical elements, such as optical amplifiers, pumping sources and other associated optical elements to configure a star network svstem. Hence, it is possible to reduce the total cost and promote the performance of the star network system. In addition, the coupler of the present invention is suitable to any pumping sources with various wavelengths, and has the advantages of facilitating the applicable combination to meet the required demands of the network system.
These and other objects and features of the invention will become more apparent from the following description taken in connection with the accompanying drawings.
Fig.1A shows a configuration of a conventional 4*4 passive
fiber-optic star coupler;
Fig.1B shows a configuration of a 4*4 active fiber-optic
coupler in accordance with the present invention;
Fig.1C shows an alternative configuration of a 4*4 active
fiber-optic coupler of the present invention;
Fig.2A shows a configuration of a transmissive 8*8 active
fiber-optic star coupler by using two units of 4*4
active fiber-optic coupler and four units of 2*2
3dB fiber-optic coupler of the present invention; configuration of a r-optic star coupler by ve fiber-optic coupler iber-optic coupler of ansmissive 16*16 active sing four units of 4*4
and four units of 4*4 oupler of the present
general form of a iber-optic star coupler zsent invention; and guration of general form active fiber-optic star h the present invention.
which shows a network 1 passive fiber-optic star ts of 2*2 3dB fiber-optic orm a 4*4 passive fiberical elements are spliced rhine. In the drawing, the ng node, the symbol " I
represents an input terminal, and the symbol " O " 0 represents an output terminal. The passive coupler as shown in Fig.1A is a bi-directional transmission device.
Therefore, the I1 to I4 represent the first to fourth input ports, while the 01 to 02 represent the first to fourth output ports.
Fig.1B shows a network configuration of the active fiber-optic coupler 2 in accordance with the present invention. which is composed of a plurality of 2*2 3dB fiber-optic couplers 21, 22, 23, 24, 25, and 26, a dichroic coupler or wavelength selection coupler 27, an optical amplified fiber 28 and an optical isolator 29.
The dichroic coupler 27 is used to mix the light signals with a pumping source and thereafter apply the mixed signals to the optical amplified fiber 28. The optical isolator 29 is used to isolate the amplified spontaneous emissions caused bv the optical amplified fiber 28. The required pumping energy is inputted from the pumping input port P1 of the dichroic coupler 27 to the optical amplified fiber 28. The fiber-optic terminus of the unused optical couplers must be cut properly to a form of slanted fiber end( abbreviated as SFE) to obviate optical reflection. All the optical elements used in the star coupler are spliced by splicing machine as the conventional technique.By controlling the splicing current and splicing time precisely, it is possible to control the splicing loss less than 0.1 åB when splicing the conventional optical fibers and less than 0.5 dB when splicing the optical amplified fiber 28 with conventional optical fibers. In such a condition, it is possible to configure a 4*4 active fiber-optic star coupler 2 by using onlv eight splicing nodes.In the alternative embodiment of the present invention, as shown in Fig.1C, the configuration of the 4*4 active fiber-optic star coupler is formed by two units of 4*1 fiber-optic star coupler 31 and 32 which are used to substitute the six units of 2*2 3dB fiber-optic coupler ?1, 22, 23, 24, 25, and 26 of the fiber-optic star coupler of the previous embodiment of the present invention as shown in Fig.1B.
Fig. 2A and 2B show the configurations of a 8*8 active fiber-optic star coupler 4 equipped with eight input/output ports in accordance with the present invention. In such a configuration, it contains two units of 4*4 active fiber-optic star coupler 2 and four units of 2*2 3dB fiber-optic coupler 41, 42, 43, and 44. All the optical elements are also spliced by splicing machine.
The 4*4 active fiber-optic coupler may be arranged on the front-end of the star coupler 2 marked with 8*8A(F) as shown in Fig.2A, and it may be arranged on the rear-end of the coupler 2 marked with 8*8A(R) as shown in Fig.2B.
When the number of ports N is more than or equal to 32, the 4*4 active fiber-optic coupler 2 may be arranged on inter-end between the couplers 2. The active fiber-optic coupler has different signal-to-noise ratio( abbreviated as SNR) depending on the position of 4x4A being placed. The position of 4x4A in is changeable to meet the coupler system requirements.
Fig.3 shows a configuration of a transmissive 16*16 active fiber-optic star coupler in accordance with the present invention, which contains four units of 4*4 active fiber-optic star coupler 2 ( 4*4A) and four units of 4*4 passive fiber-optic star coupler 1(4*4P). In the same way, all the optical elements are spliced by splicing machine, and the position of the couplers 4*4A and 4*4P is exchangeable in order to meet the system requirements.
Fig.4 shows a configuration of general form of a transmissive N*N active fiber-optic star coupler in accordance with the present invention In the drawing,
2 the number of input/output ports N = m , wherein the symbol m is any integral power of 2. It is to be understood that such a configuration will cover various network systems having input/output ports of 16, 64, 256, 1024, 4069, etc. In such a configuration, it contains m units of m*m active fiber-optic star coupler(m*mA) and m units of m*m passive fiber-optic star coupler(m*mP). Each of the passive couplers (m*mP) has stages of log (m), and
2 of 2*2 3dB fiber
system requires m/2
total.Each active
m/2 units of 2*2 3dB
Implified fiber, m/4 1 m/4 units of optical complete N*N active /2 log (N) + N/2 units
2 /4 units of optical ic optical coupler and configuration of the tic star coupler in ion. In the drawing,
2 = 2 m , and the symbol
Therefore the network work systems having 1, 2048, etc. In such a ontains 2m units of m*m
and m units of 2m*2m . In this alternative on, the numbers of the ?lifer fibers, and the ing a N*N active fiber
as that of the first
Each of the m*m active coupler has m/4 units of pumping energy input port; while each of the 2m*2m active couplers has m/2 units of pumping energy input port.The output power of each pumPing sources is distributed to K branches bv 1*k optical power splitter and thereafter supplied to the optical amplified fibers respectively. In other words, k units of active coupler 4*4A share a pumping source. The number k depends on the pump power
Pp(dBm) of each pump source, pump power required for each amplified fiber Pedf(dBm) to obtain desired optical gain, and total loss Ltotal(dB) in the pump path. The relationship of these parameters can be indicated by
10 log(K) ;s Pp - Pedf - Ltotal
The symbol K is the any integral power of 2. By using higher output power of pumping sources, optical amplified fibers with higher gain or pumping path with less pumping loss may increase the value of K.In fact, each 1*k optical splitter is a 1*k passive fiber-optic star coupler, and it may be composed of K-1 units of 2*2 3dB coupler corresponding to the specific wavelength of the light sources. In comparison, the splitting loss and excess loss in total of the N*N active fiber-optic star coupler of the present invention are only higher than that of the N*N passive fiber-optic star coupler by about 9dB.
Referring to Table I, which compares the total elements used in a transmissive N*N active fiber-optic
star coupler of the present invention to that of the conventional one.
Table I
OPTICAL PRIOR ART THE PRESENT
ELEMENTS INVENTION
2*2 3dB fiber
optic couplers (N/2)log N (N/2)log (N)+ N/2
2 2 optical amplified fibers N N/4
fibers N N/4 pumping
sources N N/4K
dichroic couplers N N/4
optical isolators N N/4
1*k optical
splitters 0 N/4K
Remark: In case that the number N is more than or equal
to 32, and the 4*4 active fiber-optic coupler is arranged on the first stage of the N*N active fiber-optic star coupler1 the optical isolators in the 4*4 active fiberoptic coupler mav be omitted.
2 2
The symbol N in the Table I may be equal to m or 2m
The present invention uses 4*4 active fiber-optic coupler as a basic element to configure a complete active star coupler. so the numbers of the optical amplified fibers, dichroic couplers and the optical isolators is the 1/4 of that of the conventional one. In addition, because various optical amplified fibers share a pumping source, the number of light sources used in the present invention mav be reduced to the 1/4K of that of the conventional one. Furthermore. in case that the 4*4 active fiberoptic coupler containing optical amplified fiber is arranged on the first stage of the N*N active fiber-optic star coupler, the optical isolator in the 4*4 active fiber-optic coupler may be omitted. As a result, the cost may be further reduced.
The advantages of the present invention are as follows: (1) The present invention uses less optical elements, such as pumping sources, optical amplified fibers, dichroic couplers, and optical isolators. Although the required amount of the 2*2 3dB optical couplers and 1*k optical splitters of the present invention is more than that of the prior art, the cost of such optical elements are cheaper. It is known that the cost of a 2*2 3dB optical coupler is 0.1% of that of a pumping source, and the cost of the pumping sourse, optical isolator, optical amplified fiber, dichroic coupler is the 80%, 12%, 7%, 1% of that of an optical amplifier respectively. Comparing to the conventional coupler, the cost of the active fiberoptic star coupler of the present invention may be reduced bv about 60% in total.In addition. by using pumping source with higher output power available in the future, the required number of the pumping sources may be further reduced. By using optical amplified fiber with higher performance, the fiber-optic star coupler can support more input/output ports.
(2) The basic element 4*4 active fiber-optic coupler may use various types of available optical amplified fiber such as erbium-doped fiber, erbium plus ytterbium-doped fiber, or praseodymium-doped fiber, etc. Also, the coupler of the present invention may be suitable to various pumping sources with different wavelength by simply replacing the dichroic coupler and optical splitter. The present invention may use various types of optical amplified fibers without limitation of the wavelength of the pumping sources. For example, in case a erbium-doped fiber is used, the wavelength of the pumping source may be 1.48 um, 0.98um, 0.82um or 1.06um. Hence, it is more easy to maintain and upgrade the coupler.
(3) The 4*4 active fiber-optic coupler acting as a basic element of the present invention may be arranged on any stage of the N*N active fiber-optic star coupler, depending on the requirements of signal-to-noise ratio and output power of the network system.
(4) The high quality of the 2*2 3dB fiber-optic coupler available in the market is rather stable, and therefore it is easy to splice an active fiber-optic star coupler by simply using a conventional splicing machine.
In conclusion, the active fiber-optic star coupler of the present invention not only can evenly transmit and distribute the signals from transmitting ports to receiving ports of the system, but also is capable of amplifying the signals to compensate the splitting loss and excess loss during transmission. In the preferred embodiment of the present invention, the active fiberoptic star coupler can support 64 or more communication ports, which allows the system to expand the number of connected terminals to upgrade the communication capability. In addition, the coupler of the present invention uses less optical elements such as pumping sources, optical amplified fibers and the other associated parts, so that the cost may be reduced. Furthermore, the configuration of the present invention can adapt to various type of pumping sources with different wavelength and makes the coupler easy to be upgraded and maintained.
Many changes and modifications in the above described embodiment of the invention can, of course, carried out without departing from the scope thereof. Accordingly, to promote the progress in science and the useful art, the invention is disclosed and is intended to be limited only by the scope of the appended claims.
Claims (6)
1. A transmissive active fiber-optic star coupler for transmitting optical signals from transmitting ports to receiving ports in a network system, comprising: at least six units of 2*2 3dB fiber-optic coupler; an optical amplified fiber for amplifying the optical signals: a dichroic coupler for mixing the optical signal with a pumping source and then sending the mixed signals to the optical amplified fiber: and an optical isolator for isolating the amplified sPontaneous emissions caused by the optical amplified fiber: wherein the star coupler spliced with low splitting loss and excess loss forms a 4*4 active fiber-optic star coupler and is expandable to a N*N active fiber-optic star coupler.
2. The fiber-optic star coupler as claimed in claim 1, wherein the pumping source is inputted to the optical amplified fiber from a pumping input port of the dichroic coupler, and the fiber-optics terminus of unused couplers are cut to a form of slanted fiber end to obviate optical reflection.
3. The fiber-optic star coupler as claimed in claim 1, wherein the six units of 2*2 3dB fiber-optic coupler are substituted by two 4*1 passive fiber-optic star couplers to form a 4*4 active fiber-optic star coupler.
4. The fiber-optic star coupler as claimed in claim 1, a transmissive 8*8 active fiber-optic star coupler being configured bv using two units 4*4 active fiber-optic star coupler and four units of 2*2 3dB fiber-optic coupler spliced by splicing machine, in which the 4*4 active fiber-optic couplers are placed on the front-end or rearend of the star coupler and the couplers may be placed on the inner-end of the star coupler in case that the amount of input/output ports N of the network is more than or equal to 32, the position of the couplers being exchangeable depending on the requirement of signal-noise ratio and the demands of the network system.
5. The active fiber-optic star coupler as claimed in claim 1, a transmissive 16*16 active fiber-optic star coupler being configured bv using four units of 4*4 active fiberoptic star coupler and four units of 4*4 passive fiberoptic star coupler, the position of the 4x4A being changeable depending on the requirement of signal-noise ratio and output power of the network system.
6. The active fiber-optic star coupler as claimed in claim 1. wherein the optical amplified fiber is responsible to various wavelength ranging from 1.3 um to 1.6um, such as erbium-doped fiber. erbium plus -tterbium-doped fiber, or praseodvmium-doped fiber.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9214805A GB2268848A (en) | 1992-07-13 | 1992-07-13 | Transmission active fiber-optic star coupler for a network system |
| CA002073808A CA2073808A1 (en) | 1992-07-13 | 1992-07-14 | Transmissive active fiber-optic star coupler for a network system |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9214805A GB2268848A (en) | 1992-07-13 | 1992-07-13 | Transmission active fiber-optic star coupler for a network system |
| CA002073808A CA2073808A1 (en) | 1992-07-13 | 1992-07-14 | Transmissive active fiber-optic star coupler for a network system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9214805D0 GB9214805D0 (en) | 1992-08-26 |
| GB2268848A true GB2268848A (en) | 1994-01-19 |
Family
ID=25675323
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9214805A Withdrawn GB2268848A (en) | 1992-07-13 | 1992-07-13 | Transmission active fiber-optic star coupler for a network system |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2073808A1 (en) |
| GB (1) | GB2268848A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2743233A1 (en) * | 1995-12-28 | 1997-07-04 | Alcatel Nv | OPTICAL SIGNAL DISTRIBUTION SYSTEM |
| US20170237507A1 (en) * | 2016-02-11 | 2017-08-17 | Huawei Technologies Co., Ltd. | Coherent channel mixing for obfuscated optical communications |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2215854A (en) * | 1988-03-26 | 1989-09-27 | Stc Plc | Active optical fibre star couplers |
-
1992
- 1992-07-13 GB GB9214805A patent/GB2268848A/en not_active Withdrawn
- 1992-07-14 CA CA002073808A patent/CA2073808A1/en not_active Abandoned
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2215854A (en) * | 1988-03-26 | 1989-09-27 | Stc Plc | Active optical fibre star couplers |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2743233A1 (en) * | 1995-12-28 | 1997-07-04 | Alcatel Nv | OPTICAL SIGNAL DISTRIBUTION SYSTEM |
| EP0783212A1 (en) * | 1995-12-28 | 1997-07-09 | Alcatel N.V. | Optical signal distribution system |
| US5926299A (en) * | 1995-12-28 | 1999-07-20 | Alcatel N.V. | System for distributing optical signals |
| US20170237507A1 (en) * | 2016-02-11 | 2017-08-17 | Huawei Technologies Co., Ltd. | Coherent channel mixing for obfuscated optical communications |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9214805D0 (en) | 1992-08-26 |
| CA2073808A1 (en) | 1994-01-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |