Fiber Optic Communications Tutorials Intoduction
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Tutorials Intoduction
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
There are two basic types of fiber used today and many different
types of Fiber Optic Cable. The two types of fiber are called
SingleMode (SM) and MultiMode (MM), and SM fiber is more expensive
but more efficient than MM fiber. SingleMode fiber is generally
used where the distances to be covered are greater. Cables come in
a variety of configurations determined by a variety of factors.
The following should give you a general overview of fiber optic
cable and its features and benefits. But, because of the variety of
types of fiber optic cable, we recommend that you call us with a
detailed description of your application and allow us to recommend
the cable best suited to meet your requirements.
While we recommend that you consult a fiber optical-cable
specialist to determine the most cost effective cable for your
application, follow these pages for a few points to consider when
specifying cable.
Fiber Optic Communications Tutorials Intoduction
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
There are two basic types of fiber used today and many different
types of Fiber Optic Cable. The two types of fiber are called
SingleMode (SM) and MultiMode (MM), and SM fiber is more expensive
but more efficient than MM fiber. SingleMode fiber is generally
used where the distances to be covered are greater. Cables come in
a variety of configurations determined by a variety of factors.
The following should give you a general overview of fiber optic
cable and its features and benefits. But, because of the variety of
types of fiber optic cable, we recommend that you call us with a
detailed description of your application and allow us to recommend
the cable best suited to meet your requirements.
While we recommend that you consult a fiber optical-cable
specialist to determine the most cost effective cable for your
application, follow these pages for a few points to consider when
specifying cable.
Tutorials Basic Cable Design
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
1 - Two basic cable designs are:
Loose-tube cable, used in the majority of outside-plant
installations in North America, and tight-buffered cable, primarily
used inside buildings.
The modular design of loose-tube cables typically holds up to 12
fibers per buffer tube with a maximum per cable fiber count of more
than 200 fibers. Loose-tube cables can be all-dielectric or
optionally armored. The modular buffer-tube design permits easy
drop-off of groups of fibers at intermediate points, without
interfering with other protected buffer tubes being routed to other
locations. The loose-tube design also helps in the identification
and administration of fibers in the system.
Single-fiber tight-buffered cables are used ase pigtails, patch
cords and jumpers to terminate loose-tube cables directly into
opto-electronic transmitters, receivers and other active and
passive components.
Multi-fiber tight-buffered cables also are available and are
used primarily for alternative routing and handling flexibility and
ease within buildings.
2 - Loose-Tube Cable
In a loose-tube cable design, color-coded plastic buffer tubes
house and protect optical fibers. A gel filling compound impedes
water penetration. Excess fiber length (relative to buffer tube
length) insulates fibers from stresses of installation and
environmental loading. Buffer tubes are stranded around a
dielectric or steel central member, which serves as an
anti-buckling element.
The cable core, typically surrounded by aramid yarn, is the
primary tensile strength member. The outer polyethylene jacket is
extruded over the core. If armoring is required, a corrugated steel
tape is formed around a single jacketed cable with an additional
jacket extruded over the armor.
Loose-tube cables typically are used for outside-plant
installation in aerial, duct and direct-buried applications.
3 - Tight-Buffered Cable
With tight-buffered cable designs, the buffering material is in
direct contat with the fiber. This design is suited for "jumper
cables" which connect outside plant cables to terminal equipment,
and also for linking various devices in a premises network.
Multi-fiber, tight-buffered cables often are used for
intra-building, risers, general building and plenum
applications.
The tight-buffered design provides a rugged cable structure to
protect individual fibers during handling, routing and
connectorization. Yarn strength members keep the tensile load away
from the fiber.
As with loose-tube cables, optical specifications for
tight-buffered cables also should include the maximum performance
of all fibers over the operating temperature range and life of the
cable. Averages should not be acceptable.
Tutorials General Cable Information
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
Coating In the manufacturing process, a protective coating is
applied to the glass fiber. The coating protects the glass from
dust and scratches which can affect a fiber's strength.
SingleMode and MultiMode Fibers There are two types of optical
fiber: singlemode and multimode. MultiMode fiber has a much larger
core than SingleMode fiber, allowing hundreds of rays of light to
propagate through the fiber simultaneously. Singlemode fiber, on
the other hand, has a much smaller core that allows only one mode
of light to propagate through the core. While it might appear that
MultiMode fibers have higher information carrying capacity, in fact
the opposite is true. Singlemode fibers retain the integrity of
each light pulse over longer distances, allowing more information
to be transmitted. This high bandwidth has made SingleMode fiber
the ideal transmission medium for many applications. MulliMode
fiber today is used primarily in premise applications, where
transmission distances are less than two kilometers.
Optical Fiber Sizes The international standard for the cladding
diameter of optical fibers is 125 microns (um). This compatibility
is important in that it allows fibers to fit into standard
connectors and splices, and allows standard tools to be used
throughout the industry. The differences among fibers lie in their
core sizes the light-carrying region of the fiber. Standard
SingleMode fibers are manufactured with the smallest core size,
approximately 810 um in diameter. With its greater
information-carrying capacity, singlemode fiber typically is used
for longer distance and higherbandwidth applications. MultiMode
fibers are available in several core sizes. The most widely used
sizes are 50 um and 62.5 um. Larger core sizes generally have
greater bandwidth and are easier to couple and interconnect.
SingleMode Step Index SingleMode fiber is designed with a
"slopindex" profile, which refers to the shape of its refractive
index profile over a cross section of fiber. The refractive index
of a material is the ratio of the speed of light in a vacuum (where
it is fastest) to the speed of light in the specific material.
In a SingleMode fiber, light is concentrated in the core;
however, some light travels in the inner part of the cladding at
normal operating wavelengths. The diameter of the spot of light as
it travels through the fiber is called the mode field diameter
(MFD). MFD is an important parameter for determining splice loss
and the fiber's resistance to bendinduced loss.
Choosing Cable There are many different types of fiber optic
cables. All of the cables are defined by the number of fibers in
the cable, the type of fibers (MM or SM), the size of the fiber
(50, 62.5 or 125um) and the type of material used to enclose the
fibers. The material used to enclose the fibers have many names.
Some of the names are generic and others are names used by the
cable manufacturer. To limit any confusion, you should begin with
the following questions.
What type of fiber do I need?
How many fibers do I need?
Do I need indoor or outdoor cable?
Will the cable be in a hazard environment and require rugged
construction?
Will the cable be underground and require moisture and rodent
protection?
Do you need Plenum, Tempest, NEC, UL, or CSA rated cables?
The remainder of your cable concerns should be finalized by your
cable supplier after you have explained your application in
detail.
What is and why use PLENUM Cable Most states and cities have
adopted for their building codes the National Electrical Code (NEC)
recommendations regarding acceptable wiring methods for cable
installed in the air handling or plenum spaces above suspended
ceilings. The NEC states that all cable installed in plenum spaces
must be installed in metal conduit unless classified by an approved
agency as having fire resistant, low smoke producing
characteristics.
Cables that are not classified by an approved agency, such as
Underwriters Laboratories (UL), as having fireresistant, low smoke
characteristics must be installed in conduit. Conduit installation
can increase the initial installed cost of a cable system by an
average of 100 percent, and rerouting cables in conduit to
accommodate moves, adds and changes is costly and disruptive.
Cables made with several different materials have the UL low
smoke, low flame spread classification. However, plenum cables
insulated with TEFLON fluoropolymer resin provide superior
electrical performance at a reasonable cost for all computer,
voice, data, video, control and life safety
Tutorials General Cable Information
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
Coating In the manufacturing process, a protective coating is
applied to the glass fiber. The coating protects the glass from
dust and scratches which can affect a fiber's strength.
SingleMode and MultiMode Fibers There are two types of optical
fiber: singlemode and multimode. MultiMode fiber has a much larger
core than SingleMode fiber, allowing hundreds of rays of light to
propagate through the fiber simultaneously. Singlemode fiber, on
the other hand, has a much smaller core that allows only one mode
of light to propagate through the core. While it might appear that
MultiMode fibers have higher information carrying capacity, in fact
the opposite is true. Singlemode fibers retain the integrity of
each light pulse over longer distances, allowing more information
to be transmitted. This high bandwidth has made SingleMode fiber
the ideal transmission medium for many applications. MulliMode
fiber today is used primarily in premise applications, where
transmission distances are less than two kilometers.
Optical Fiber Sizes The international standard for the cladding
diameter of optical fibers is 125 microns (um). This compatibility
is important in that it allows fibers to fit into standard
connectors and splices, and allows standard tools to be used
throughout the industry. The differences among fibers lie in their
core sizes the light-carrying region of the fiber. Standard
SingleMode fibers are manufactured with the smallest core size,
approximately 810 um in diameter. With its greater
information-carrying capacity, singlemode fiber typically is used
for longer distance and higherbandwidth applications. MultiMode
fibers are available in several core sizes. The most widely used
sizes are 50 um and 62.5 um. Larger core sizes generally have
greater bandwidth and are easier to couple and interconnect.
SingleMode Step Index SingleMode fiber is designed with a
"slopindex" profile, which refers to the shape of its refractive
index profile over a cross section of fiber. The refractive index
of a material is the ratio of the speed of light in a vacuum (where
it is fastest) to the speed of light in the specific material.
In a SingleMode fiber, light is concentrated in the core;
however, some light travels in the inner part of the cladding at
normal operating wavelengths. The diameter of the spot of light as
it travels through the fiber is called the mode field diameter
(MFD). MFD is an important parameter for determining splice loss
and the fiber's resistance to bendinduced loss.
Choosing Cable There are many different types of fiber optic
cables. All of the cables are defined by the number of fibers in
the cable, the type of fibers (MM or SM), the size of the fiber
(50, 62.5 or 125um) and the type of material used to enclose the
fibers. The material used to enclose the fibers have many names.
Some of the names are generic and others are names used by the
cable manufacturer. To limit any confusion, you should begin with
the following questions.
What type of fiber do I need?
How many fibers do I need?
Do I need indoor or outdoor cable?
Will the cable be in a hazard environment and require rugged
construction?
Will the cable be underground and require moisture and rodent
protection?
Do you need Plenum, Tempest, NEC, UL, or CSA rated cables?
The remainder of your cable concerns should be finalized by your
cable supplier after you have explained your application in
detail.
What is and why use PLENUM Cable Most states and cities have
adopted for their building codes the National Electrical Code (NEC)
recommendations regarding acceptable wiring methods for cable
installed in the air handling or plenum spaces above suspended
ceilings. The NEC states that all cable installed in plenum spaces
must be installed in metal conduit unless classified by an approved
agency as having fire resistant, low smoke producing
characteristics.
Cables that are not classified by an approved agency, such as
Underwriters Laboratories (UL), as having fireresistant, low smoke
characteristics must be installed in conduit. Conduit installation
can increase the initial installed cost of a cable system by an
average of 100 percent, and rerouting cables in conduit to
accommodate moves, adds and changes is costly and disruptive.
Cables made with several different materials have the UL low
smoke, low flame spread classification. However, plenum cables
insulated with TEFLON fluoropolymer resin provide superior
electrical performance at a reasonable cost for all computer,
voice, data, video, control and life safety systems.
Tutorials Different Types of Cable
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
BREAKOUT CABLE Breakout cables are designed with alldielectric
construction to insure EMI immunity, and are available with UL/CSA
OFNR/FT4 or UL/CSA OFNP/FT6 listings. These cables are obtainable
in a wide range of fiber counts and can be used for routing within
buildings, in riser shafts, and under computer room floors. The
Breakout design enables the individual routing, or "fanning", of
individual fibers for termination and maintenance. In addition to
the standard duty 2.4 mm subunit design, a 2.9 mm heavy duty and a
2.0 mm lite duty design are also available.
INTERCONNECT CABLE
Cable for interconnecting equipment is available in singlemode
and multimode fiber sizes and its all dielectric construction
provides EMI immunity . Available in oneand twofiber designs, these
cables are optimized for ease of connectorization and use as
"jumpers" for intra-building distribution. Its small diameter and
bend radius provide easy installation in constrained areas. This
cable can be ordered for plenum or riser environments. Products
include single fiber cable, twofiber Zipcord, and twofiber DIB
Cable. Uncabled fiber, coated only with a thermoplastic buffer, is
also available for pigtail applications with inside equipment. All
cables are available with UL/CSA OFNR/FT4 or UL/CSA OFNP/FT6
listing.
LOOSE TUBE CABLE
Loose tube cables are for general purpose outdoor use. The loose
tube design provides stable and highly reliable transmission
parameters for a variety of applications. The design also permits
significant improvements in the density of fibers contained in a
given cable diameter while allowing flexibility to suit many system
designs. These cables are suitable for outdoor duct, aerial, and
direct buried installations, and for indoor use when installed in
accordance with NEC Article 770.
FEATURES
Different fiber types available within a cable (hybrid
construction).
Lowest losses at long distances, for use in duct aerial, and
directburied applications.
Wide range of fiber counts (up to 216).
Available with singlemode and multimode fiber types.
All dielectric or steel central member.
Loose Tube Cable is also available with armored construction for
added protection.
LOW SMOKE, ZERO HALOGEN CABLE HalexRTM is a low smoke, zero
halogen fiber optic cable, designed to replace standard
polyethylene jacketed fiber optic cables in environments where
public safety is of great concern. In addition to having low smoke
properties, HalexR cable meets the NEC requirements for risers,
passes all U.S. flame requirements for UL 1666 and UL 1581, and is
OFNR listed up to 156 fibers.
The Halex family of fire safe cables consists of HalexR for
indoor riser requirements and HalexL for outdoor loosetube
requirements. HalexL is the industry's first loosetube, gelfilled,
lowsmoke zero halogenated optical cable that is OFN listed with up
to 144 fibers.
HalexR uses ChromaTek "L" jacketing to protect the optical
fibers it surrounds. This special jacketing exceeds all index
requirements as stated in New York State article 15, U.S. Navy NES
711 and ASTME662 for smoke density. Special compounds in HalexR
also prolong cable life and reliability, making it highly resistant
to flame, acids, chemicals and oils.
HalexR cable is available with any optical fibers, both
singlemode and multimode, in loose tube, tight buffer or breakout
constructions. Attenuations as low as 0.4 dB/km, and bandwidths as
high as 1000 MHZ/km, can be supplied.
LXE LIGHT GUIDE EXPRESS ENTRY CABLE The LXE (Lightguide Express
Entry) sheath system is designed with the loop distribution market
in mind, where express entry (accessing fibers in the middle of a
cable span) is a common practice.
The LXE sheath system achieves a 600 pound (2670 N) tensile
rating through the use of linearly applied strength members placed
180 degrees opposite each other.
High density polyethylene (HDPE) is used for the cable jacket to
provide both faster installation, through a lower coefficient of
friction, and optimum cable core protection in hostile
environments.
FEATURES
Strength members in cable sheath (not in cable core).
Nonmetallic cable core.
LIGHTPACK CABLE
Lightpack Cable consists of fiber "bundles" held together with
color coded yarn binders. Cable can hold up to 144 fibers and still
maintain a large clearance in the core tube. A waterblocking
compound, specifically designed for LIGHTPACK Cable, adds extra
flexibility, protects the fiber and virtually eliminates
microbending losses. Lightpack cable is compact size, rugged
design, contains a high density polyethylene sheath and has a high
strengthtoweight ratio.
INDOOR/OUTDOOR LOOSE TUBE CABLES The RLT Series of loose tube
fiber optic cables is designed for installation both outdoors and
indoors in areas required by the (NEC) to be riser rated Type OFNR.
They meet or exceed Article 770 of the NEC and UL Subject 1666
(Type OFNR). They also meet CSA C22.2 No. 232M1988 Type OFNFT4.
All of the RLT products utilize a proprietary ChromaTek 3
jacketing system that is designed for resistance to moisture,
sunlight and flame for use both indoors and outdoors. These cables
are loose tube, gelfilled constructions for excellent resistance to
moisture. They are available with singlemode or multimode fibers
with up to a maximum of 72 fibers.
Because these outdoor cables are riser rated, they eliminate the
need for a separate point of demarcation, i.e., splicing to a riser
rated cable within 50 feet of the point where the outdoor cable
enters the building as required by the NEC. These cables may be run
through risers directly to a convenient network hub or splicing
closet for interconnection to the electro-optical hardware or other
horizontal distribution cables as desired.
No extra splice or termination hardware is required at the
entrance to the facility, and cable management is made easier by
the use of just one cable. This installation ease is especially
useful in Campus type installations where buildings are
interconnected with outdoor fiber optic cables.
TACTICAL/MILITARY CABLE Tactical cable utilizes a tight buffer
configuration in an all dielectric construction. The tight buffer
design offers increased ruggedness, ease of handling and
connectorization. The absence of metallic components decreases the
possibility of detection and minimizes system problems associated
with electromagnetic interference.
FEATURES
Proven compatibility with existing ruggedized connectors.
Lightweight and flexible: no antibuckling elements required.
Available in connectorized cable assemblies.
Available with 50, 62.5 and 100 micron multimode fibers, as well
as singlemode and radiationhardened fibers.
TEMPEST CABLE DESCRIPTION For use where secure communications
are a major consideration, and Tempest requirements must be met.
The Tempest rated cable is available in a variety of cable
constructions.
Tempest relates to government requirements for shielding
communications equipment and environments.
One common application is the use of fiber optic cable in
conjunction with RF shielded enclosures. These enclosures have been
specially constructed to suppress the emission of RF signals, and
must meet the Transient Electro-magnet, Pulse Emanation Standard
(TEMPEST).
For a system to be TEMPEST qualified, it must be tested in
accordance with MIL-STD285, and it must also meet the requirements
stated in NSA 656. All elements of the system, individually and
combined, must meet the TEMPEST standard. In the case of fiber
optics, the "system" consists of the cable (which is dielectric and
nonconductive), and the tube through which the cable passes.
Tutorials Connectors
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
THERE ARE MANY TYPES OF CONNECTORS. THE ONE YOU USE DEPENDS UPON
THE EQUIPMENT YOU ARE USING IT WITH AND THE APPLICATION YOU ARE
USING IT ON. THE TWO WORDS TO REMEMBER ARE:
"COMPATIBILITY" AND "RELIABILITY."
Except for special applications, the most commonly used, readily
available and cost effective connector is the "ST" connector.
Because of the general compatibility of the ST connector with most
equipment, it is always a good place to start when deciding upon
the connector you may need.
When deciding upon the proper cable to use, there are only three
issues to consider.Is it compatible with my equipment?Will I be
using it in extremely hazardous conditions?Does it require special
clearance?
REVIEW THE PICTURE BELOW FOR A FEW OTHER TYPES OF
CONNECTORS.
Tutorials A Cross Section of Various Cable Types
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
A - OUTSIDE PLANT CABLE B - PREMIS DISTRIBUTION CABLE C -
SIMPLEX, DUPLEX AND TWO FIBER ROUND CABLE D - BREAKOUT CABLE E -
LOOSE TUBE RISER CABLE F - SINGLE ARMOR LOOSE TUBE CABLE G - DOUBLE
ARMOR LOOSE TUBE CABLE
Tutorials Wave Division Multiplexers
Introduction
Fiber Optic Basics
Basic Cable Design
General Cable Information
Different Types of Cable
Connectors
A Cross Section of Various Cable Types
Wave Division Multiplexers
Wavelength Division Multiplexing An Alternative To Leased Fiber
LinesFiber-optic systems are now the key solution to linking
high-speed LAN and WAN networks within and among buildings. The
number of high-speed networking applications using fiber as the
physical-layer backbone continues to grow, such as:
Fiber Distributed Data Interface (FDDI), running at 100Mbps
Synchronous Optical Network (SONET), running at 155Mbps and
622Mbps
ESCON, running at 200Mbps
Gigabit Ethernet, running at 1,000Mbps
Fibre Channel, running at 1,062Mbps and below
High-Performance Parallel Interface (HIPPI), running at
1,200Mbps.
Optical fiber provides the backbone speed and distance
capability to support all these applications and more.
The Problem With Fiber
Mainframe systems capable of supporting ESCON are some of the
most fiber-intensive applications in wide-scale deployment today.
These enterprise systems generally run on multimode 62.5/125 micron
(m, .001 millimeter) fiber for connecting devices within 3 km or on
single-mode 9/125 m for distances of up to 20 km. Although these
fibers easily handle the 200Mbps data streams, each channel or
device interface requires dedicated use of fiber connections. For
applications such as on-line remote transaction processing and
disaster recovery - which often run at full speed 24 hours per day,
seven days per week - the fibers are dedicated exclusively. The net
result is that an ESCON network requires from a few pairs to a few
hundred pairs of fibers among facilities to deliver the necessary
performance and connectivity.
The cost and availability of this fiber are key issues in
planning connectivity between facilities. Mainframe applications
continue to grow. Transaction processing is expanding beyond
current system capabilities, requiring more devices and more
connections. The new role of the mainframe as an Internet server
also has a dramatic effect on device and fiber demand.
Wave Of The Future
Wavelength Division Multiplexing (WDM) is a new option for
adding applications or expanding existing applications over
currently available fiber links. WDM offers a cost avoidance in
that existing fiber can support multiple applications over the same
link without any performance penalty. In addition, WDM technology
requires fewer links to support the performance needs of a new
application.
Multiplexing techniques have a long history and are now widely
used in communications. Frequency Division Multiplexing (FDM) is
the standard technique used in analog transmission systems, such as
cable television. Each communications channel uses a separate
frequency. Time Division Multiplexing (TDM) is standard for digital
transmission systems. Data communications and long-haul
telecommunications systems use TDM to combine multiple low-speed
channels in specific time slots of a higher-speed channel.
A much newer technology, WDM is already a critical tool for many
high-speed communications systems. WDM works on the same principles
as FDM and TDM, except the channel discriminator is wavelength
instead of frequency or time. Since light waves of different
lengths do not interfere with each other, multiple wavelength
signals can be transmitted through the same optical fiber without
error. By allowing multiple high-speed communications applications
to share the same fiber simultaneously, WDM unlocks optical fiber's
tremendous bandwidth capability: more than one terabit per
second.
The telecommunications industry is investing heavily in WDM
technologies. Communications service providers, such as AT&T,
MCI and US Sprint, are running out of bandwidth capacity and are
looking for more cost-effective, time-sensitive alternatives to
installing more dedicated fiber lines. Industry standards are now
being created around high-speed WDM systems. Although these systems
present excellent capacity expansion alternatives for
central-office telecommunications, they don't meet the speed and
cost requirements of the data communications industry.
New optical multiplexers employ WDM to increase existing fiber
capacity for data communications environments. The WDM equipment
converts each input data stream into separate wavelengths (colors)
and simultaneously transmits these channels through the same
optical fiber. Since each wavelength is completely isolated from
the others, creating a discrete channel, and since the WDM unit
never processes the data, protocols can be mixed within the same
link. Essentially the unit creates "virtual fibers" from one fiber.
As a result, existing fiber can be leveraged to add new
applications within a metropolitan area.
Many critical components combine to produce this
performance.
Remote wavelength conversion: The converter board houses the
critical elements to change the local channel into the remote
wavelength necessary for the long-distance WDM signal. Each
converter board receives the local device signal into an
electrooptic receiver. This signal is directly forwarded to drive
the remote single-mode laser, which is specific for each channel.
This process is similar to conventional multimode-to-single-mode
conversion, except the single-mode laser is wavelength specific.
This example is a four-channel system - remote channel 1 operates
at 1300 nanometers (nm), while channels 2 through n are widely
spread wavelengths around the 1550 nm band. The remote link can
support distances up to 16 km and greater. Where a single-mode
long-distance device is already running over a single-mode remote
fiber, removing the channel 1 converter allows the addition of
three new applications onto the existing fiber.
Passive WDM: The heart of the unit, the WDM passively (no power
required) combines and separates the specific wavelengths on one
remote fiber. The WDM uses an interference film technology
developed more than 20 years ago by the optics and photography
industry for reflective and antireflective lenses. Now dramatically
refined, the technology allows wavelength-selective reflection
through roughly 100 layers of the film with nanometer
precision.
The WDM combiner uses the interference technology with fused
optical fiber couplers to combine all wavelengths onto one remote
"transmit" fiber. The WDM splitter is a duplicate device that
operates in the opposite direction. It receives the combined
wavelengths on the single remote "receive" fiber and splits them
onto separate fibers.
Local signal regeneration: Once the passive WDM element
separates the remote signals, each signal is routed back to the
converter board, which reconverts it to the original 1300 nm
wavelength. The output power to the local devices is between -14
dBm (decibel relative to 1 milliwatt) and -21 dBm and matches the
protocol input on the other side of the WDM link.
Practical Benefits
Compared with dedicated fiber alternatives, WDM technology
offers many key benefits, including:
Leveraging of existing fiber capacity
Lower cost
Elimination of long-distance single-mode converters
Faster access to new channels
Protocol independence.
Leverage: WDM can leverage existing fiber to provide new fully
operational channels immediately. For example, a four-channel WDM
system can create three new application paths for every fiber pair.
The economic advantages for distances beyond 4 km are significant.
The ability to leverage fibers also benefits private fiber
installations on a campus. Although high-fiber-count cables can be
less expensive to install in short-distance runs (less than 2 km)
than WDM equipment, the long lead time for fiber cable and
installation crews can exceed several months.
Lower cost: WDM provides a more economical solution for
high-speed data communications applications. Its cost advantages
come from two main points:
1) WDM equipment is often less expensive than private cable and
leased-line alternatives for distances longer than 2 km.
2) WDM equipment provides a granular or incremental growth
solution for adding new applications among facilities. WDM
equipment is added as needed, as opposed to the installation of
additional private cable, which requires a substantial up-front
investment.
The cost of installing dedicated cable varies significantly by
location, accessibility, right of way and total length. Regardless
of these variables, the cost to add fiber capacity always includes
a large initial investment. This investment must be justified on
the basis of immediate applications and longer-term projections of
application growth to amortize the cost of the new cable over all
these applications. However, a WDM solution is a more granular
choice for adding capacity, since it can be justified by only a few
applications and capacity can be increased at any time. WDM thus
incurs added capacity costs only as needed and eliminates the need
for guesswork in future growth projections.
Most WAN applications do not provide the option of installing
private fiber cable. Instead, a private fiber service can be leased
on a per-pair basis. Although a much more granular solution than
the large initial capital outlay of purchased and installed cable,
leased fiber services are generally expensive; the cost can vary
from $100 to $1,000 per fiber per mile per month, depending on
region, availability, distance and number of fiber pairs needed.
Service providers often demand a 10-year to 20-year commitment for
leased fiber, limiting the flexibility for running a business (for
example, data center relocation). WDM minimizes the impact of such
commitment because fewer fibers are required and the equipment is
re-deployable at any place and time.
No long-distance converters: WDM technology uses single-mode
remote lasers to create the separate wavelengths for the WDM
system. This feature incorporates a multimode-to-single-mode
conversion process required to interface the local input (usually
multimode) with most long-distance fiber communications systems,
saving the space and cost of converters or long-distance laser
cards.
Faster access to new channels: As the base of installed fibers
fills up and most service providers move toward specialization,
dedicated fiber is becoming harder to obtain in most metropolitan
areas. Even when fiber can be procured, it often takes four to 12
months to have complete point-to-point service connected.
Protocol independence: WDM systems create completely
independent, fully transparent paths over each fiber. This allows
the combination of multiple application protocols over the same
fiber without any issues of latency, speed, proprietorship,
software setup, etc. A multi-channel WDM link will behave as
multiple "virtual" fiber pairs, letting users mix and reconfigure
protocols as needed.
Summary
WDM systems present a new alternative for network connectivity
in the enterprise. They offer cost advantages, flexibility and
quick response to application growth. Business managers can show
reduced costs and improved investment returns. Data communications
managers have the flexibility to add a variety of applications and
reconfigure devices as needed immediately, with no penalty on
performance. Capacity planners can be more accurate and ensure
availability of resources when needed. In new LAN and WAN
applications, WDM systems are an excellent choice for network
connectivity.
Fiber Optic Data Communications Multiplexers MODEL LT8116
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MODEL LT8116
16 Channel Multiple Interface Multiplexer
16 Async Channels
Speeds Up to 38.4 Kbps
Power Redundancy & Fiber Optic Redundancy
LEDs for "Tx," "Rx," "Alarm" & "PWR"
Field Interchangeable Interfaces: RS232, RS-422, Dry Contact
Relays
Local & Remote Loopback Single Mode & Multimode Rack
Mount or Standalone
Applications
The LT8116 provides a particularly inexpensive method for
connecting large numbers of async terminals, printers and status
collecting devices. It is also used in harsh environments where
EMI/RFI interference and lightning conditions may exist.
Description
The LT8116 is an affordable 16-channel fiber optic multiplexer
with interchangeable interfaces and optional power/optical
redundancy. It supports data rates up to 38.4Kbps with no controls.
Because the electrical interfaces are modular, they are
interchangeable in 4-channel increments at any time--before or
after installation. Available interfaces include RS-232 or RS-422.
Fiber optic connectors are ST (FC or SMA are optional); electrical
connectors are RJ11. Power is 9 to 12VDC or 115/230VAC with an
external power cube.
Specifications
Data RatesAsync
up to 38.4 Kbps per channel
ChannelsCapacity
16 Async Channels
OpticalTransmitter
LED/ELED
Receiver
PIN
Wavelength
850nm/1300nm multimode
1300nm single mode
Fiber Optic connectors
*ST (FC or SMA optional)
Loss Budget
15 dB multimode
850nm/1300nm @50 um
15 dB multimode
850nm/1300nm @62.5um
20 dB single mode
1300nm @9 um
ElectricalConnector
RJ-11
Interface
RS-232, RS-422, Dry Contact Relay
(check factory for other kinds)
SystemBit error rate
1 in 10X9 or better
Visual indicator
"Tx", "Rx", "Alarm", "Sync", "Power
Diagnostic
Local Loopback
PowerDure power source
12 VDC @400ma
optional:
115 or 230 VAC with external power cube
TemperatureOperating
-10"C to 50 C
Storage
-40 C to 901'C
Humidity
95% non-condensing
PhysicalHeight
(6.5 cm) 2.60"
Width
(18 cm) 7.20"
Depth
(25 cm) 9.75"
Weight
(1 .36 kg) 3 lb
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MODEL LT3000
Multimode-Single mode Fiber Optic Converter/Repeater
Converts Multimode to Single Mode
Converts Single Mode to Multimode
Reads Opto-Digital Data up to 165 Mbps
Increases Distance Between Nodes
Cross Connects Fiber Types
Performs Optical Repeater Function
Applications
Ethernet, Token Ring, FDDI & SONET
Extend Transmission Distance
Fiber Optic Repeater
Description
The LT3005/3020 Fiber Optic Mode converters give users the
unique ability to convert multimode format to single mode format or
single mode to multimode for data transmission.
Lascomm's mode converters are intended for Ethernet, FDDI &
SONET environments and support data rates up to 165 Mbps.
These conversions can benefit users by extending transmission
distances and/or enabling different fiber types to be used with
dissimilar installed fiber.
The LT3020 takes multimode optical-digital information and
converts it to single mode for transmission over duplex single mode
fiber optic cablefor speeds up to 5Mbps. Model LT3005 takes in
multimode optical digital information and convert it to single mode
format for transmission of speeds up to 165/200Mbps.
Lascomm's mode converters are available with ST and FC type
connectors. Power can be either 115/230 VAC or -48VDC.
Specifications
Data RatesLT3020
Up to 5 Mbps
LT3005
Up to 165/200 Mbps
OpticalTransmitter
LED/ELED/LASER
Receiver
PIN
Wavelength
850nm/1300nm multimode1300nm single mode
Fiber Optic Connectors
STor FC
Loss BudgetsLT3050
16dB 1300nm SM @9/125 um
LT3005-05
16dB 1300nm SM @9/125 um
LT3005-25
25dB 1300nm SM @9/125 um
LT3005-35
34dB 1300nm SM @9/125 um
SystemBit error rate
1 in 10X9 or better
Visual Indicators
Power
(Green)
SM REC
Single Mode IN (Green)Lights at -33+-1dBm
MM REC
Multimode IN (Green)Lights at -33+-1dBm
XMT
Laser output OK (Green) - Lightswhen laser is transmitting
properly
PowerPower source
12VDC @ 300ma
optional:
115 or 230 VAC w/ext. power cube
optional:
-48 VDC
TemperatureOperating
0 C to 50 deg. C
Storage
-40 C to 90 deg. C
Storage
-40 C to 90 deg. C
Humidity
95% non-condensing
PhysicalHeight
(1.75 cm) 1.75"
width
(24.7 cm) 9.75"
Depth
(31.5 cm) 12.5"
Weight
(2.27 kg) 5 lb
Fiber Optic Data Communications WDM MODEL LT4001
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MODEL LT4001
Channel Fiber Optic Multiplexer (Wave Division Multiplexer)
Doubles Use of Existing Fiber Optic Cable
Transparent to Data Format
Passive Device - No External Power Needed
Stand Alone or Rackmount
Applications
The LT4001 is ideal for situations where existing fiber optic
cable capacity is limited. Because it doubles existing cable
capacity by transmitting bi-directional signals over a single
fiber, it eliminates the need to install additional fiber optic
cable.
Description
The "Channel Surfer," Model LT4001 Fiber Optic Wavelength
Division Multiplexer, enables 1300nm and 1550nm wavelengths to be
transmitted simultaneously on the same fiber optic cable. The
direction of the optical signals can be in the same direction or
oppo-site directions.
Transparent to incoming data, the LT4001 effectively doubles
exist-ing cable capacity by multiplexing two separate channels over
one single mode fiber. Dual two-channel units are also available.
Each LT4001 unit separates incoming optical signals between 1300nm
and 1550nm. Thus, a user needs to connect the TC4001 to a device
(transceiver, modem, etc.) with a 1300nm single mode trans-mitter
at one end and a 1550nm single mode transmitter at the other
end.
The LT4001 fiber optic connectors are ST or FC. Because it is a
passive device, it requires no power.
Specifications
Bandwidth1310/1550nm
15nm
Optic Ports1310nm
1
1550nm
1
1310nm+1550nm
1
connector
*ST (FC optional)
Insertion LossStandard
30dB
Directivity(Return Loss)
>55dB
WavelengthsSingle Mode
>1310 & 1550nm
Typical PolarizationSensitivityPSD
