Fiber optics communication page
Index
In the early days of fiber-optic transmission (in the 1970s and early 1980s)
telecommunication network developers were attracted by
the single-mode optical fiber's low loss, low weight and inherent protection
against tapping (no one then had been able to tap an optical fiber, nowadays
it can be done but it is not easy).
Optical fiber allowed developers to bridge long distances with a small number
of repeater stations and run high speed data rates at the same time.
Depending on the fiber optic cable and the equipments on the ends you
can transmit you data over fiber optic cable form tens of meters
up to even hundreds of kilometers.
There are two major basic fiberoptic types: singlemode and multimode.
The concepts of singlemode and multimode are really straightforward,
is is primarily a question of how large the core diameter is. In multimode fiber the core diameter ranges from 50 to 100 microns (typical cable types for this are 62.5/125 micrometer and 50/125 micrometer models).
In singlemode fiber, the core diameter is a in order of 7 to 9 microns.
If you are dealing with an average building or campus, you don't have to worry about singlemode versus multimode. You can easily use either for almost any application, present or future.
If, on the other hand you're dealing with wiring up long distances, then singlemode vs. multimode is of concern. You use singlemode fiber cables for long distances (typically 30-50km between repeaters) and very high data rate capacities
(gigabit per second).
Multimode fiber is qualified at two primary wavelengths: 850nm (short wavelength) and 1300nm (long wavelength). The de-facto bandwidth standard for 50/125µm optical fiber is 500 MHz·km @ 850nm and 500 MHz·km @ 1300nm. Fiber provides its lowest attenuation in the second optical window as 1310 nm, so that wavelenghts most commonly used. 850 nm is used for some short-haul transmission due availability of very low cost components for this wavelength.
The power levels sent fiber opti cable depend on application. Typically
the power levels used are form 50 nW up to 10 mW (-45 dBm to +10 dBm).
Typical telecommunication applications use 1300 and 1550 nm wavelengths
at power range of +3 to -45 dBm (50 nW to 2mW).
Typical data communication applications use wavelengths of 665,
850 or 1300 nm at -10 to -30 dBm signal levels (1 to 100uW).
CATV systems typically use 1300 and 1550 nm wavelengths
at +10 to -6 dBm signl level (250 uW to 10mW).
Signal is transmitter to the optical fiber using a LED
(in low power short distance applications) or using
a semicondictor laser. The signal is detected on
the other end of the cable using suitable photodetector
(usually PIN photodiode).
Silicon photodiodes are sensitive to light in the range of 400 to 1000 nm and germanium and indium-gallium-arsenide photodiodes are sensitive to light
in the range of 800 to 1600 nm.
- An Enlightening Guide - lists players in optical communications field
- A Practical Guide to Testing Fiber Optic Components and Networks
- Ask Lennie and Uncle Ted (The FAQs) about communication cabling - information on different cable types and fiber optics
- Asynchronous Transfer Mode (ATM) Passive Optical Networks (PONs) Tutorial - This tutorial discusses the economics, operator and customer benefits, and technological development of optical distribution networks with asynchronous transfer mode passive optical networks (ATM PONs)
- Coming Soon: Fiber to the Home
- Copper or Fiber? What's the real story?
- Fiber Amplifiers - introduction
- Fiber Connector Termination Methods
- Fiber Optic Safety - it's stupid to look into a fiber when you don't know what is being transmitted through it
- Fiber optics that was then, this is now - fiber-optics has been around for more than six decades, but it became a household word during the 1990s, the decade of electronic communications
- Fiber-Optic Technology Tutorial
- Fiber Optimism - Nortel, Lucent, and Cisco are battling to win the high-stakes fiber-optics game.
- Fiber Shortage Has Carriers Scrapping
- Fiber Survivability: Protecting The Passives - the protection of fiber optic patchcords is essential to the survival of the network
- FIBER Vs COPPER: Sometimes it's not an easy choice - choosing between fiber-optic and copper interconnect systems is sometimes difficult, entailing considerations of distance, cost, required bandwidth, and specialized expertise
- Glossary of Fiber Optic Technical Terms and Acronyms
- Hitachi overview of fiber-optic communication developments - report from 1994
- Horizon Photonic Networking Area - photonic networking information, including Roadmap towards the Optical Communication Age book
- Introduction to Fiber Optics
- Introduction to Optical Transmission in a Communications Network Tutorial
- OC-48, OC-192, and beyond (Part 1) - Networks are all about more bandwidth, and 2.5-Gbps OC-48 and 10-Gbps OC-192 promise to deliver it. However, many of the important standards are still moving.
- OC-48, OC-192, and beyond (Part 2) - Figuring out how to partition functionality at OC-48 and OC-192 speeds is only part of the battle of building a robust design that can later scale to faster speeds and increased services. At some point, however, all those high-speed ports have to come together, and that only compounds your problems.
- Optical Access Tutorial
- Optical Fiber Cabling in 568-A specification
- Optical Metro Edge Tutorial - demand for broadband voice and data services has exploded and fiber is needed in metropolitan networks
- Optical Networks Tutorial
- Optical networking lightens carrier-backbone burden - more and more users are finding faster ways to send data and are thus overburdening long-haul communications backbones
- Optical power levels of fiber optic communication systems - how much power is put to that tiny fiber
- Point-to-Point or Mesh Topologies in the Metro Optical Network Tutorial - This tutorial highlights the key advantages of adopting a point-to-point strategy and eventual mesh topology, a new approach in transport technology
- Sweetness and light: how the Web has opened up opportunities in optical components - article series
- Switching the light fantastic - As fiber carrying capacities move into multiterabit rates, equipment at the metropolitan-service/long-haul interface must cope with growing channel counts, not just channel speeds. Stretched between optical-electrical-optical solutions and the yet unrealizable all fiber network lie a number of devices that can, some say, push electrophotonic transduction to the enterprise interface and perhaps to your door.
- Teach Yourself Fiber Optics Online - fiber optics cabling course
- The ABC's of Fiber Management
- The Direction of the Optical-Networking Market Tutorial
- Thoughts About Fiber Optics - general discussion of fiber optics
- Working with fiber - fiber optics is a much simpler technology than most people believe, it is just different than normal cables
- Analog components add fiber to your communications diet - To effectively interface between the digital electronic world and the optical world, you need to use analog components designed to accommodate the unique characteristics of electro-optical components
- BER caused by jitter and amplitude noise in limiting optoelectronic repeaters with excess bandwidth - a simplified analysis of noise in concatenated limiting (2R) optoelectronic repeaters
- Breaking The 2.5-Gbit/s Barriers - as Gigabit Ethernet and OC-48/STM-16 nodes start permeating the communications industry, the bandwidth requirements on the line and across the backplane are increasing exponentially, 40-Gbit/s backplane bandwidths are commonplace today and traditional backplane bus structures are on the verge of extinction, the new buzzword is serial
- Design Challenges For Fiber Optic LAN Transceivers
- Design and layout rules eliminate noise coupling in communication systems - high-speed telecommunication and data-communication schemes, such as SONET/SDH networks, noisy high-speed digital logic often shares board space with sensitive analog circuitry
- Fiber battles copper for gigabit serial links - you can now get gigabit connectivity with minimum fuss via standard module and connector families, and you can switch between copper and fiber links without significant redesign
- GaAs ICs Arm 10-Gb/s Optical Communications Systems
- High-Speed PHY Design - high speed fiber optic transmitters and receivers give challenges also to electrical design on circuit board
- Intelligent Data Recovery - clock and data recovery (CDR) function is a key element in any high-performance fiber-optic link
- Optical/Electrical Conversion in SDH/SONET Fiber Optic Systems
- POS-PHY Level 3: Enabling High-Speed Networking Applications - there is call for inter-chip interface to handle sheer variety of services such as ATM, packet over SONET/SDH (POS), Frame Relay, and Gigabit Ethernet
- Statistical Confidence Levels For Estimating Error Probability
- The right test equipment simplifies measuring BER in burst-mode systems - without the right equipment, experimentally verifying burst-mode receiver designs can be difficult
For the last two decades, it has been a dream for telecommunication carriers to develop a new era wherein a variety of services are provided over an optical access platform instead of existing Plain Old Telephone Service (POTS)-oriented metallic networks. Passive optical network (PON) is a promising technology for building optical access networks.
Wavelength-Division Multiplexing (WDM) is a technology for transmissing many
diferent signals through one optical fiber cable using many different optical
carries which have different wavelength.
At first, wavelength-division multiplexing was used with only two wavelengths -
1310 nm and 1550 nm. However, this was suitable only for limited applications:
for example, applications in which analog optical-cable television signals
co-existed with digital optical-telecommunication signals.
Dense Wavelength Division Multiplexing (DWDM) in an attempt to
make optimum use of the Erbium-doped fiber amplifier's gain band,
1530 nm to 1570 nm to carry tens of different signals in that wavelegth range.
A number of signals coming from different transmitters with different center
wavelengths are combined into one fiber using an optical multiplexer
and amplified almost equally using Erbium-doped fiber amplifier.
With regard to optical equipment, the scheme has the noticeable advantage of
being transparent for data protocols. Basically, it is possible
to mix analog and digital signals or, more commonly, digital signals of
different protocols. One application od DWDM is to increase the fiber
optic cable capacity by packing up to 100 high speed data channels to
one fiber optic cable. ITU Recommendation G.692 specifies 100 GHz/0.8nm
channel spacing on 32 nm grid centered at 193.1 THz/1552.52nm
(preliminary standards works are specifying 50 GHz and 25 GHz spacing).
Synchronous Digital Hierarchy (SDH) in Europe and the Synchronous Optical
Network (SONET) in North America, is gaining popularity in telecommunication
networks thanks to its interconnecting flexibility and ease of management.
The SONET and SDH format allows different types of data to be transmitted on
one line. SONET and SDH are long term solutions in telecommunication networks
for a mid-span-meet between vendors. SONET and SDH standardize the rates and
formats to avoid complicated multiplexing/demultiplexing, coding/decoding
process to convert a signal from one format to another format. Today,
most countries are in the process of replacing the old PDH hierarchy with this
new standard.
Fibre Channel (FC) is the most common choice for transport in
storage area network (SAN) implementations.
Fibre Channel is a data management system, a unified approach to
storage, network and control. It provides accessible supervision,
scalable performance and versatile connectivity, via simple
point-to-point topologies with dedicated bandwidth or loops with
shared bandwidth.
The promise of Fibre Channel storage is, that by using a high-speed
networking technology, you can easily connect a wide variety of storage
devices to your server and you can share content stored on these
storage devices. Much of this promise has been delivered, but there are
still some issues to be resolved.
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