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Fiber Optics 101
Assembly Styles:
Duplex Connector Assembly
Duplex Assembly with Simplex Connectors
Simplex Jumper Assembly
Simplex Pigtail Assembly
Optical Assembly Terminology:
Optical jumpers can take many forms. The most common form is a duplex
jumper, with one fiber acting as a Tx (transmit leg) and the other fiber
acting as the Rx (Receive leg).
Optical jumper users must understand the relationship between the connectors, cable style and glass fiber. The term "Simplex" indicates that a single optical fiber is being used in the assembly but does not mention what type of glass is to be used (e.g. singlemode, multimode, etc...). The term "Duplex" indicates that the assembly contains two optical fibers.
"Duplex" connectors allow two fibers to be terminated while "Simplex" connectors allow just one. Some simplex connectors can be joined together to form a quasi-duplex connector.
Optical Fiber Cable:
Jumper Cable
A duplex cable contains two fibers while a simplex cable contains just
one. However, jumper cable design varies based on the primary applications.
The most common jumper styles are:
Simplex
Duplex Round
Duplex "Zipcord"' Round
Ribbon Fiber Cable
Certain optical connectors require ribbon cable constructions. In such
cases, ribbon cables can take jacketed or unjacketed forms. Below, you
will find the construction of a typical jacketed 12 fiber ribbon cable.
Optical Glass Fiber Basics:
An optical fiber is comprised of two inseparable sections - a
core and it's cladding. Light propagates through the core section and
the cladding provides an internal reflection boundary. Light will propagate
through the cladding layer but poorly.
A multimode fiber has a large core thus allowing many light rays (modes) to propagate.
A singlemode fiber has a very small core, allowing only one mode of light to be transmitted.
Optical glass is sold based on the core / cladding dimensions. The most common multimode fiber is 62.5 /125 microns where 62.5 is the size of the core while the 125 microns is the size over the cladding. Over the past few years, 50/125 glass has grown in popularity due to it's exceptional performance at the 850 nm window. The core size of a singlemode fiber is called the mode diameter and ranges between 8.3 and 10 microns. It may be written 9/125 or 8.3-10/125.
OVER VIEW OF FIBER OPTIC CABLE ADVANTAGES OVER COPPER:
• SPEED: Fiber optic networks operate at high speeds - up into
the gigabits
• BANDWIDTH: large carrying capacity
• DISTANCE: Signals can be transmitted further without needing to
be "refreshed" or strengthened.
• RESISTANCE: Greater resistance to electromagnetic noise such as
radios, motors or other nearby cables.
• MAINTENANCE: Fiber optic cables costs much less to maintain.
In recent years it has become apparent that fiber-optics are steadily replacing copper wire as an appropriate means of communication signal transmission. They span the long distances between local phone systems as well as providing the backbone for many network systems. Other system users include cable television services, university campuses, office buildings, industrial plants, and electric utility companies.
A fiber-optic system is similar to the copper wire system that fiber-optics is replacing. The difference is that fiber-optics use light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. Looking at the components in a fiber-optic chain will give a better understanding of how the system works in conjunction with wire based systems.
At one end of the system is a transmitter. This is the place of origin for information coming on to fiber-optic lines. The transmitter accepts coded electronic pulse information coming from copper wire. It then processes and translates that information into equivalently coded light pulses. A light-emitting diode (LED) or an injection-laser diode (ILD) can be used for generating the light pulses. Using a lens, the light pulses are funneled into the fiber-optic medium where they transmit themselves down the line.
Think of a fiber cable in terms of very long cardboard roll (from the
inside roll of paper towel) that is coated with a mirror.
If you shine a flashlight in one you can see light at the far end - even
if bent the roll around a corner.
Light pulses move easily down the fiber-optic line because of a principle known as total internal reflection. "This principle of total internal reflection states that when the angle of incidence exceeds a critical value, light cannot get out of the glass; instead, the light bounces back in. When this principle is applied to the construction of the fiber-optic strand, it is possible to transmit information down fiber lines in the form of light pulses.
