02-03-2010, 07:42 AM
Reported by: Edward Yin
Student ID: 8920213
Fiber-Optic Communication System Introduction
First, the history of optical fiber communication
Modern "optical fiber communication" development began in the 1960s, while making the "optical" has become the main force of the present and future of communication is based upon our two events of excitation: first, in 1960 the U.S. physicist de Umenoto (Theodore Harold Maiman) succeeded in making the ruby oscillation have a "laser light." The second was de 1966, scientists Charles Kao (Charles Kao), and George A. Hockham, they predicted the production of "optical fiber" to let "waves" in which one kilometer transmission, there is still the original 1% of light energy, then the fiber optic cable will be able to like the general, as a transfer tool. Because at the time, even the best optical fiber, light waves in which the transmission had to make 20 meters to the original light energy to reduce energy by 1%.
That by the year 1970, the Bell Labs can be successfully produced at room temperature continuous oscillation of the semiconductor laser (Semi-Conductor-Laser), and the Corning glass works (Corning Glass Work) to produce bad per kilometer is less than 20 dB lower eradication loss of quality Quartz (Silica) fiber, the "fiber" technology by leaps and bounds.
Today, due to the development of optoelectronic technology, each less than 1 dB km decline eliminate, the transmission bandwidth is higher than 800MHZ optical cable already mass-produced, coupled with the "high-end digital multi-tasking" (High Order Digital Multiplex) technology development and high performance, "Optical Components" (Opto-Electronic Device) the development, per-second transmission speeds of up to 90 million "bit (bit)", and even per second, 400 million "bits" of the high-speed large-capacity optical communication systems, and currently has practical stage.
Second, the principle of optical fiber communication
When we use the radio transmission information, you must first into a series of telecommunications numbers, by the base stations has become a "radio signals (Radio Signal)", while the receiving station, after receiving these signals, and then convert it into a telecommunications number, after decoded into the information we need. Similarly, light can also blink through light source, such as the flash on or off signal arising from a series of graphics, which we call "light signal." Light greater than the electrical capacity of the transmission of information, meaning that light can be broken into shorter pulses, so at the same time can form a higher density and informative graphics. In this rate, through the merger of a graphic element into a "heap (Stack)", can be in the same fiber at the same time send a lot of different information. Just like cars from the interchange into the highway, it would not hit the other car. This is why the "optical fiber" can accommodate a lot of information in which the transfer reason.
Third, the advantages of optical fiber communication
(A) long-distance communications, reduce costs:
1. For example, 1.3 micron wavelength of the optical fiber for transmission, each kilometer of about 0.4 ~ 0.5dB loss;
The 1.5-micron fiber of about 0.2 ~ 0.25dB per km of the low transmission loss.
2. And the traditional copper cable transmission system comparison, the optical fiber communication so that the relay transmission distance increased to
Dozens of kilometers, and can significantly reduce the number of repeaters to reduce the cost of communications systems.
3. For example: If from Taipei to Keelung, the distance, but more than 20 kilometers; the use of a fiber optic connections,
Then the Keelung area will be no need for large rooms. As the low-loss optical fiber transmission, an increase of relay range
Transmission, reducing system cost and complexity, more suitable for long-distance transmission.
(B) optical quality of thin, light and rich could be around, easy assembly into a beam, so the assembly into a fiber optic cable laid, the
Channel space can be saved. Effectively improve the channel utilization, configuration space, economy, and suitable for
Aircraft, satellites and ships.
© The fiber has great communication bandwidth, bandwidth of up to 1 ~ 2GHz or more. An ordinary one coaxial cable
Cable's bandwidth is about 330MHz ~ 550MHz, contrast, optical fiber has a high capacity of the set hearing.
(D) the general Jie Wei quartz glass fiber material, which has a non-corrosive, fire-resistant, water resistant and long life of the special
, Coupled with optical fiber to have excellent flexibility and response, good protection of outside and tensile material,
So that optical transmission can save operating costs.
(E) Since optical media such as quartz glass, are a good insulator, will not be of electromagnetic waves, etc.
Interference, that are easily affected by lightning or high electric field area, can greatly enhance the communication fidelity.
(Vi) confidentiality is not a high optical signal radiation away from the fiber is suitable for the military, banking and electrical connections
Brain network.
As the optical fiber system has many advantages mentioned above, allowing all countries are optimistic about the prospects for optical fiber communications, and has devoted considerable financial and human resources to research and development. With the advent of the information age, large capacity, low loss, excellent communication network reliability is essential, while the optical fiber communication system is the best option. Therefore, can be expected in the near future, most of the copper cable will be replaced by optical fiber.
4, optical fiber communication system type
The whole range of fiber optic communication industry, including very wide, from the central office equipment, transmission equipment, transmission equipment in the components, and client network equipment ... and others have proprietary fiber-optic communications products, although the product rather complicated, but in order to is now available commercially mass-production products to the classification of its components can be broadly classified into three categories: made of fiber and optical fiber cable, optical active components, and optical passive components, etc..
The so-called optical fiber, quartz glass is still based on the fine fiber made from the most important product, has also recently appeared in plastic as the material of plastic optical fiber; the number of core plus the cladding material be merged into Fiber cable is referred to as fiber optic cable; while light active component will include the provision of the light source optical transmitter, receive the light source optical receivers, and optical amplifiers ... and so on; in the optical passive components in the product contained more numerous, for example, the most common fiber optic connectors, optical modulators, optical isolation devices, optical fiber coupler, optical attenuator ... and so on. (See Table 1)
Table 1: Optical Fiber Communication System type
Category Description
Fiber can be divided into three layers: core layer (core), cladding layer (clad), the protection layer (optical cable).
According to material can be roughly divided into: Glass fiber (SiO2) and the Plastic Optical Fiber (PC, PS, mCOC, PMMA, Sol-Gel).
Including the single-mode fiber optic cable (48%), multi-mode fiber optic cable (9%), submarine optical cable (43%).
According to material can be roughly divided into: Indoor (PE), outdoor (PVC).
Between the optical active component related to photovoltaic energy conversion, including: optical transmitter, optical receivers, optical transceivers, optical amplifiers, surface-emitting laser (VCSEL), optical switches, tunable lasers, L Band Amplifier.
Optical Passive Components Optical connectors (the largest share), optocouplers, optical attenuator, optical signal modulation, optical polarizer, optical isolation, filters, light source Splitter, waves Splitter.
Other DWDM systems
Optical Communication Materials
Optical local area network equipment
Telecommunications optical transmission equipment
CATV optical transmission equipment
Fiber-optic communications equipment, measurement
The following will be more important to explain the several parts:
Fiber:
1. Fiber glass SiO2, snag material made of plastic optical transmission medium, as light waves can be transmitted through optical fibers to transfer data and other information, with a transmission frequency band, communication volume, low-loss, immune to electromagnetic interference, light weight characteristics of .
2. Fiber structure, the inner layer contains a very fine glass column, called the axis core (core), outer circle known as the coating layer longer (cladding) surrounding the glass, due to the refractive index coating layer of glass over shaft Core glass column is small, axial core in the conduction of light to the coating layer, if refraction, total reflection will be the way turn back the core axis, the light waves also increased the efficiency of transmission of many. Therefore, the optical fiber from the inside out is divided into three parts: 1, shaft core part (Core): namely, fiber optical signal transmission part. 2, coating layer part (Cladding): coating the shaft core periphery, in order to send light to the core. 3, protective layer (Jacket): coating layer of shell, to prevent external damage to the coating layer and the fiber core axis.
3. Fiber practical application, it can set multi-beam optical fiber, and then to protect the layer of ways to enhance protective shell, it becomes the so-called fiber optic cable. As the fiber bandwidth can be used greatly at this stage to use an area of approximately 565 Mbps up and down in the future, cutting through the bandwidth and the WDM mode, the transmission bandwidth is expected to further expand the
4. Fiber type areas: can be summarized into a single film, more film and special optical fiber, in which single-mode fiber transmission due to only one mode, suitable for large-capacity long-distance optical fiber communication, optical fiber backbone built when the demand for cloth the largest share of output value over the years the proportion is about Bacheng, multi-fiber core diameter larger membrane, which can transmit a variety of modes of transmission performance while poor natural result of the application at the regional optical networks is the use of, the future growth rate is better than single-mode fiber . Will include a special plastic optical fiber and other optical fiber, the market volume is relatively small.
Cable
1. Malpractices fiber optic cable assembly, add water, coating as well as supporting media in order to achieve the maintenance of the existing optical fiber transmission characteristics, ease of construction and protection of fiber optic capabilities. The structure in general can be divided into optical fiber cable buffer layer, and anti-tension cable heart body, coating, and waterproof layer and some other. But according to their structural differences, may be slightly divided into (1), loose belt-type cable (2), groove-type cable (3), groove-type ribbon cable (4), four types of ribbon fiber optic cable (5), optical / electrical hybrid cable (6), indoor fiber optic cable (7), communications cable and other broad categories
2. China now truly home-made fiber manufacturers are not many, mostly by foreign buying optical fiber, coupled with a sealed tube into a fiber optic cable manufacturing. Foreign firms to Corning optical fiber, Lucent, Alcatel, Sumitomo, etc. for the industry leader. (See appendix 1, appendix II)
optical active components:
The entire fiber-optic communications system architecture which, fiber optic active components can be described as playing a "continuity," an important role as the main function of optical active components are carried out optical (or electro-optical) conversion, and optical signal amplification and so on.
Through the electro-optical conversion, the original use of electrical signals can be the process of dissemination of information, freedom to switch to optical signals for the, soon after arrival to photoelectric conversion, the optical signals into electrical signals back to the original, and then from other electronic equipment application , it makes the optical fiber communication can be achieved. In addition, the process of transmission, the signal inevitably be subject to the environment and the impact of communication media, the growth of decay as the propagation distance, in order to to maintain the accuracy of information, so in the dissemination process, you must use the amplifier will have a signal attenuation of the enhanced continue to send. Precisely because of optical active components, and so has the conversion and amplification functions, the dissemination of information to make more efficient use of fiber-optic whom, it does have a fiber optic active components, "continuity" function.
A, optical transceiver modules:
i. Department of integrating optical transceiver module optical transmitter (transmitter) and the optical receiver (receiver) two functions, while the formation of a single optical signal transceiver module. Therefore, it can be divided into communication with the light source (transmitter) and review the majority of optical device 2, in which communication with the light source some of the major use of two kinds of LED and LD light sources, LED unit though relatively inexpensive, but the LD light source in nature due to better coupled with newly developed surface-emitting laser (VCSEL) light source superior performance, with the proportion of LD of the optical transceiver modules there is a rising trend.
ii. while the inspection part of the optical device is particularly optical transceiver module of the most important key components need to have high sensitivity, high bandwidth, high reliability and low cost, easy manufacturing requirements. The current inspection devices used in optical components, mainly divided into PIN diodes, and APD diodes into two categories, Among them, the PIN diodes with lower production costs, accounting for a larger proportion.
iii. the future of optical networking will continue to enhance the transmission rate request, light source and review the performance requirements of optical devices will become the key to the development of optical networks.
B, optical amplifiers:
i. In the past, before the invention of optical amplifiers have not yet, you must first restore the optical signal back to electronic signals, the use of electronic signal amplifiers amplified and then converted to optical signal transmission. Such a process is not only complicated, but the application of electronic signal amplifier transfer rate and bandwidth is fixed, if the transmission speed optical fiber communication systems, you must upgrade all of the next update, and so makes the equipment costs have increased, but the optical amplifier does not have this trouble. Recent high-density WDM (Dense Wavelength Division Multiplexing, DWDM) system, introduction, making data transfer rates of surge, but was able to spread, it is thanks to optical amplifier to remove the barriers of traditional photoelectric conversion thanks. In addition to being in the relay transmission, the optical amplifier can be added to the transmitter to increase the output power, or for the receiver as a preamp to increase the sensitivity.
ii. optical amplifier is a photoelectric conversion without conditions, direct the optical signal to be amplified optical active components, due to long-distance fiber-optic communications will face serious light signal attenuation issue, so fiber optic network at appropriate distance from the namely, the need for repeaters or optical amplifier to amplify signals. Because of the optical amplifier without having photoelectric conversion, the network upgrade or adjust the format, then we do not like a repeater in general be replaced.
iii. optical amplifier can be divided into three categories: (1), optical fiber amplifier (OFA); (2), semiconductor optical amplifier (SOA); and (3), Raman amplifier (RA) three categories. Fiber amplifier is the use of rare-earth ions doped glass gain characteristics of the fiber directly to the signal amplification; semiconductor optical amplifier principle is similar with the laser diodes can be in the DC bias will be incident on the active layer of the optical amplification; la Man is the use of optical amplifiers and fiber non-linear interaction between atoms to produce the Stoke line up amplification. Current technology more mature optical amplifiers are erbium-doped fiber amplifier (EDFA), praseodymium-doped fiber amplifier (PDFA), three kinds of semiconductor optical amplifier.
optical passive components:
The main function of optical passive components is the optical signal for continuation and differences, filtering, attenuation or isolation, so that such components, including connectors, couplers, wavelength division multiplexer (Wavelength-Division Multiplexer), optical switches, filters, isolators and attenuation, etc.. Optical fiber communication systems throughout the building fabric, the overall communication network links all depends on fiber optic passive components to achieve, while the passive components are closely related to the quality of virtue or vice and communications. For example, a good passive components can make a page link insertion loss (insertion loss) as low as possible, allowing a clearer signal, and ensure the stability of the page link line will not drop it or loose a result of bad communication, so it can be said passive components is a fiber optic communications infrastructure.
A, optical connectors:
i. Fiber Optic Connector is a device at the fiber end mechanical devices can be used as a fiber optic connection time path of successive parts. Different types according to their follow-fiber, fiber optic connectors can be broadly divided into single-mode fiber optic connector and multimode fiber connectors, while the Ruozai according to semi-permanent and permanent continuation of the use of a different fiber, they can still be divided into light in the mechanical bonding, as well as two follow-mode welding machine.
ii. general measure of how good or bad performance of fiber optic connectors, optical signals pass through the two connected in the connector, its depletion of energy derived from the insertion loss and reflection from the connector end surface reflection loss calculated data will be the main two criterion. In the future in line with line construction and ease of end-use fiber-optic connectors, fiber-optic network rollout in the high labor cost factors, will be the main growth products. "Table 2"
Table II: a variety of environmental requirements for the connector loss
The degree of damage use of the environment
0.2dB below the long-range communication system to connect with the
02.-0.75dB system connection within the building or facility with the
1-3dB at cost as a priority consideration, applications used to connect
B, fiber couplers:
i. Fiber Optic Coupler Splitter in general may be called, the main light signal used to carve up from an optical fiber section, due to optical signal transmission is not like the copper wire inside Telecom's general ease of differences, thus wishing to light signals scattered to a different pipeline, that is required to spectrophotometric optical fiber coupler.
ii. Therefore, the optical fiber coupler is widely used in the user loop system, LAN, cable TV network systems. Configuration in general can be divided into pairs of branches, tree / star and the three types of WDM; while according to the different manufacturing methods can also be divided into welding optical fiber sintering, micro-optics and planar waveguide-type three types of optical fiber coupler.
iii. which is a graded refractive micro-optical lens, optical fiber rods will be oriented parallel to the light, after the expansion, and then semi-transparent mirror to light into two parts, respectively, after focusing rod lens coupling into the fiber. Malpractices two optical fiber sintering and melt together, stretched, so that the nuclear core due to synergies and integration to achieve light coupling, the current lowest cost, highest reliability and the highest rate of the domestic industry producing the coupler products. Planar waveguide approach is the use of flame hydrolysis deposition and optical lithography, the waveguide structure fabricated on silicon on in order to achieve spectral coupling, foreign operators to use the technology to produce a higher proportion of couplers.
C, sub-wave multiplexer:
i. WDM errant simultaneously with an optical fiber transmission of several different wavelengths of light signals to double the capacity of optical fiber transmission technology developed by the division of labor, due to WDM EDFA can be combined such as optical signal amplification technology, give full play to optical transmission The high-bandwidth features, will be hundreds of different wavelengths of light signals transmitted in the same fiber at the same time, while the principles developed in accordance with its sub-wave multiplexer (WDM: Wavelength Division Multiplexing) has become associated in recent years, the most popular fiber-optic passive components .
ii. a two-way wavelength division multiplexer of passive components, its performance can be multi-wavelength optical signals of different combinations of an optical fiber, and its solution may be a multi-tasking performance fiber optic transmission of signals of different wavelengths of light separated.
Ding, fiber grating:
Fiber Bragg Grating is a new technology, its fairly wide range of applications, therefore not only be used for optical fiber communication, so in the future market, the application will be quite optimistic about the market; fiber Bragg grating from the fiber core principle of its work Bragg grating in the reflection mechanism, as of now the most extensive and most economical of the system into the phase mask method, production method is to strip fiber coating, the place some time after the high-pressure hydrogen tank removed, and then placed in the phase mask ( Phase Mask), the longer excimer laser (Excimer Laser) exposure of about ten minutes can become a reflection of a certain wavelength of the reflector, while the reflected wavelength determined in accordance with the phase mask; while major equipment required for the KrF quasi - molecular laser, phase mask and the associated optical apparatus; The following diagram is an icon system to do.
Figure 1: the production of optical fiber grating icon
Fiber Bragg Grating fairly wide range of applications that can be used
¢ Tunable Wavelength Laser (Tunable Laser)
¢ EDFA filter (gain modified components)
¢ Smart Structure (Smart Structure)
¢ Wavelength selector
¢ WDM filter module manufacturing
¢ band suppression filter
¢ fiber optic coupler and fiber with spin-wave devices can be done to take Wong Zao multiplexer (OADM)
¢ chirped phase mask (Chirped Phase Mask) produced chirped grating (Chirped Fiber Grating) as a dispersion compensator (Dispersion Compensator)
Therefore, optical communication fiber Bragg grating is a very important research and development firms focused
E, light switches:
Optical switch for all-optical network, optical fiber signal cross-linked the main components, its role will be primarily to establish or interrupt a light path in order to determine the direction of optical signal transmission.
Been, optical attenuator:
i. optical attenuator can be used to absorb or reflect light signal margin, or for system loss evaluation and testing. As the optical signals through the various components of the transmission, both will lead to the light source frequency drift and the line noise, therefore, through the optical attenuator to absorb the associated noise will be to ensure the quality of an important high-speed optical communication components.
ii. optical attenuator is now widely used in optical communications market, with its output after the connector, coupler, the market demand is still steadily growing.
G, optical isolator:
Optical isolator is a two-port optical passive components, the main function is to enable the optical signal attenuation in the transmission direction is very small, but in the opposite direction of the light will not be reflected. Mainly used in optical transmitter modules, optical amplifiers, as well as in high-transmission system, to reduce the noise impact.
Sim, high-density wavelength division multiplexer
High-density wavelength division multiplexer (Dense Wavelength-Division Multiplexer) for the recent communication was a major invention, its working principle and the same wavelength division multiplexer, but its work on the same wavelength bands, and the interval between the different wavelengths less than 1nm, is because of its very short wavelength interval, so used to be very narrow bandwidth light source, such as DFB lasers, because of its narrow bandwidth of up to 0.2nm, it is quite suitable for use. In addition, due to multi-tasking part of the solution used in the filter must also be very high precision in order to ensure the purity of the output signals. DWDM light source mainly used 1550nm wavelength range, different wavelength interval is only about 0.8nm, and therefore use more of its light source and narrow bandwidth DFB laser, while the filter characteristics to the decision to DWDM good or bad. "See Appendix III"
5, optical fiber communication applications
In the optical transmission less than 30 years of history, the early stage of development are mainly based telecommunications transmission, but due to the technological sophistication and the different needs of the increase in the past 10 years has gradually amplified optical fiber application development to the optical local area network and cable television optical transport market, because the transmission of optical communication must be very precise, it has also led to associated to the measurement of optical communications market's rise.
The application of optical fiber communication systems at present can be divided into three broad categories: telecommunications optical transmission, fiber-optic local area network connection, cable connection, the bottom of the 11 to be explored.
1. Telecommunication optical transmission in
Telecommunications optical transmission equipment for the optical communications industry, the largest application of those
In the most early stage telecommunications structure is determined by a central switch (Centralized Switch, also known as the clearing house) and all users (End User) a direct connection, known as the central switching network (see Figure 2), which only serves a single line end-users, but in which the distance between the various users of varying lengths, in order to avoid long lines confined to only be occupied by a user, resulting in communications equipment due to inefficient use of waste formed, so class network (Hierarchical Network) also made derivatives. Class network architecture (see Figure 3), in principle, at the local clearing house by the and user switching network composed of a central responsibility of the central switching network and then to a larger bandwidth trunk (Carrier Trunks ) mutual connection, and use multi (Multiplexing) approach to increase the transmission capacity of trunk, and now the use of more multi-tasking technology is TDM (Time Division Multiplexing, TDM)-based; in class, under Network , due to regional communications by various regions of the central switching network processing, while the long-distance communications will be via the multi-tasking machine to transmit through the trunk, so a regional communication and long-distance communications, the use of resources can be more efficient allocation of and have access to a larger transmission capacity.
Figure 2: The Central Exchange network infrastructure (Centralized Switching)
Figure 3: class network infrastructure (Hierarchical Network)
Optical fiber transmission bandwidth and speed far superior to copper cable
Telecommunications infrastructure in the past, due to a single voice transmission channel (voice channel) can only 64Kbps of bandwidth, so in all regions of the trunk between the majority of the clearing-house use only accommodate a higher throughput of copper cable as the connection media, such as DS3 (also known as T3, 44.736Mbps) and E3 (34.368Mbps) ... and so on, but with the increase in the amount of telecommunications transmission, copper lines in the past has gradually been insufficient bandwidth to use, so have a higher transmission capacity The cable also begun to use the trunk, and even has begun to replace copper cables; in the traditional fiber-optic systems, optical fiber transmission speed is several times more than copper cables, such as Synchronous Optical Network Systems / synchronous digital hierarchy (SONET / SDH), the lower optical fiber transmission rate up to OC-3 rates were 155Mbps, the speed of nearly 5 times the copper E3, if a high optical transmission rate OC-192 (10Gbps), its speed E3 is almost 300 times (see Table III).
Table III Comparison of copper and fiber optic transmission speed
With the increasing application of fiber-optic technology, SONET / SDH optical transmission protocol standard also been worked out, SONET (Synchronous Optical Network, Synchronous Optical Network) and SDH (Synchronous Digital Hierarchy, SDH) are based on the basic structure synchronous transfer mode as a basis, but by the United States to set SONET fiber-optic transmission standard (U.S. regulation), SDH is the ITU (International Telecommunication Union) is modeled according to SONET, followed by the set adapted for the world outside the United States simultaneous transmission standard, this In addition to the standard applied to optical fiber network, but also applicable to other synchronous transfer be based on a standard transmission. At present many countries around the world long-distance backbone network are commonly used by SONET / SDH fiber-optic network, most of them in order to provide 2.5Gbps, 5Gbps, or a 10Gbps system mainly on the relay route is the OC-3 and OC - 12 for most.
ATM fiber optic network enables a more flexible and scalable
But because the SONET / SDH synchronous transmission technology such as a part of the inherent limitations and data information transfer increases, ATM network transmission will be the future of another major backbone transmission infrastructure, next generation backbone network will be designed for a number of ATM architecture . ATM (Asynchronous Transfer Mode, ATM), as its known as a non-synchronous transfer mode, the most important special place that is to use a number of fixed-length frame (Fixed-length Cells) (53 bytes) for information transmission, This shipping method provides a chronological nature of information (such as voice and video) for high-speed (2.5Gbps and above) transmission, and can achieve the quality of service (Quality of Service, QoS) guarantees. As the ATM network construction with a flexible, future equipment, scalability, and speed ... and other features, so the rise of ATM will also be useful in the development and prevalence of optical networking, optical fiber transmission can play an even greater effectiveness. WDM and DWDM multiplexing techniques such as the emergence of optical fiber transmission can be more efficient, greatly enhance the scope of application of optical fiber communication.
Although the SONET / SDH fiber-optic transmission for the present a more accessible means of transmission, but due to fiber-optic SONET architecture information is only a single frequency (ie, monochromatic) is transmitted in the current era of bandwidth demand to that seems to be more inconsistent with the benefits, it also has a different wavelength as a multi-tasking WDM (Wavelength Division Multiplexing, WDM) technology, WDM is to use the simple principle of a fiber optic transmission of two or more different wavelengths (colors ) of optical signals in order to achieve additional capacity or bandwidth of the multi-effects; In recent years, fiber-optic multiplexing technique to further high-density reached WDM (Dense Wavelength Division Multiplexing, DWDM), the so-called DWDM and WDM principle is similar, except to be as high-density DWDM way for eight or more different wavelengths of light through an optical fiber transmission of information at the same time, to today's technology can be a maximum of about 80 multi-pen data packet transmitted on a single optical fiber in order to fully to achieve the effect of broadband and optical fiber communication greatly reduces the transmission costs; If DWDM technology combined with erbium-doped fiber amplifier (EDFA) the use of, and now has become a wired communications to increase transmission capacity of the best solution.
2. Fiber optic local area network connection
People for the bandwidth demand-led the development of fiber-optic local area network
As mentioned earlier, due to high prices and demand, so is limited to the early development of long-distance fiber optic communications lines on the use of, but in recent years a rapid increase in traffic volumes and the explosive growth of the Internet, the optical networking applications long-distance transportation from the past (Long Haul Transport) of the backbone network extended to the city transport (Metro Transport) of the district lines, the next one or two years because of Datacom traffic will increase, technological advances, and the cost of optical communication down, leaving the application of optical communication access once again to the end of transmission (Edge Transport) of the relay route (such as Fiber to the Building ... and so on) development.
While the rapid decline in the price of fiber optic products, fiber optic product prices due to the average consumer should be reduced to an acceptable range and the actual project erection difficulties, so in the near future fiber-to-table (Fiber to the Desk, FTTD) should remain a non - more common, but in the fiber optic local area network is the backbone of the coming year can be seen. Optical local area network currently in the mainstream of Fast Ethernet (100Mbps and above) and Gigabit Ethernet (1Gbps or above), due to optical local area network on the cost considerations are more important than the telecommunications backbone network, so most of its light source using low-cost LED and the newly developed VCSEL (Vertical Cavity Surface Emitting Laser, Vertical Cavity Surface Emitting Laser), will increase the popularity of optical fiber local area network.
The popularity of the current regional fiber optic network backbone on a limited, but based on the evaluation of this market is not inferior to the telecommunications backbone network of the market, if the future due to decline in the price of fiber optic products can be achieved FTTD, then the relevant active and passive components market, a huge would be beyond words.
3. CATV optical transmission
CATV HFC bi-directional transmission led to the rise, has also increased the demand for optical fiber cable
Early cable television transmission medium is used coaxial cable (Coaxial Cable) transmission by use of the coaxial cable from the band is only 50MHz to 550MHz, running approximately 100 channels, the other remaining bands formed because of not using a waste, after Because HFC (Hybrid Fiber Coaxial, fiber coaxial cable) architecture and the emergence of two-way transmission, so cable systems can also be used in data transmission. HFC is mainly used to signal from the ground-side optical fiber (Head-end) sent to the user in the vicinity of the light cast Placement (Optical Network Unit, ONU), then after the concatenation way coaxial cable to high-quality RF signals sent to the 500 ~ 1000 users at.
HFC with the 50 ~ 550MHz frequency band to download TV shows, and the other using the band 550 ~ 750MHz modulation approach to data, images, or phone ... such as a digital download service, in addition to re-use 5 ~ 35MHz frequency band as the uplink signal using the .
Because these two years the use of coaxial cable for bi-directional transmission market is a multiple of the growth of the old type of traditional architecture have to be re-laying cable HFC, so cable TV transmission market will also be a fiber optic transmission equipment and components, the other fast-growing a driving force.
6 Conclusion
Sum up the above, in the future bandwidth requirements have continued to grow, the trend of optical communication is already taking shape, the Taiwanese firms naturally can not give up enormous opportunities in this one. On the whole, the communications equipment market is still dominated by major players in Europe and the United States, in the master specification formulation and existing market base, the scope of domestic manufacturers can not dwell, therefore the main opportunities for Taiwan businessmen are still in optical communication Zero Group parts manufacturing.
In the optical communications components, our firms more time engaged in passive components, development of a more mature and the current degree of automation of production is not high, are more dependent on manpower, so carry European and American firms outsourcing orders more easily. Be relatively low especially in the future of communications components, including various types of connectors, couplers and filters and other passive components and low-power active components, this part of the product requirements is not as harsh long-distance transmission, focusing on the costs are low, and the demand is huge, this part just right for Taiwanese manufacturers to develop, therefore, Taiwanese firms should be aware that this block of the current market.
Because Taiwan is only a few manufacturers to produce optical fibers, so output is still small, but the cable industry is quite developed, most of the optical fiber is imported from abroad, and then processed into mainland China in its cable, cable operators are beginning to meet Taiwan The domestic demand, but as capacity development and the input of many industry, at present the cable companies are active in the international market
In short, fiber-optic communications to flourish in today's occasion, domestic manufacturers can play an active investment products and manufacturing technology R & D, coupled with an appropriate strategic alliance, the future business opportunities will be very large, while the fiber optic industry will become a future star in the Taiwan stock market industry.
