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Fiber Optics

FIBER CONNECTOR TYPES

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Fiber Optics

There have been many different types of fiber optic connectors developed throughout the years, many of which are now obsolete.

We will concentrate on the most commonly used connectors and the fiber connectors that are recognized by the standards.

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Fiber Optics

The industry standard connectors are rigid ferrule connectors and can be broken down into four categories:

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Fiber Optics

PC: Physical contact polish.

These connectors are hand polished and typically have an attenuation of -30dB. PC refers to how the ferrule of the connector is polished.

These connectors can cause back reflection into the ferrule and into the transmitter.

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Fiber Optics

APC: Angled physical contact.

This is done by the manufacturer, they cut the ferrule to an 8 degree angle to reduce back reflection.

These connectors have an attenuation of -60dB and are used by CATV and Phone companies.

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Fiber Optics

SPC/UPC: SUPER POLISH CONTACT, done by the manufacturer. -40db

ULTRA POLISH CONTACT, done by the manufacturer. -50db

These finishes are to help prevent back reflection into the transmitter.

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Fiber Optics

Flat: Flat polish connector.

These connectors are polished by the manufacturer typically have an attenuation of -30dB.

Flat polish connectors control back reflection fairly well

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Fiber Optics

PC polish and flat polish connectors are intermateable with reduced return loss performance.

APC polish connectors are not intermateable with any other type, and furthermore there are different and incompatible APC types which are only partially compatible

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Fiber Optics

The way a ferrule is polished is critical to connector return loss performance. A "flat polish" connector will cause around -14.7 dB return loss unmated, and up to -11.7 dB mated. ( e.g. two reflections ).

A "PC" or "physical contact" connector will cause around -14.7 dB return loss unmated, and between -30 and -60 dB mated, or around -20 dB for multimode fiber.

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Fiber Optics

The back reflection losses are a result of the light being reflected back to the light source.

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Fiber Optics

You may also see designations such as SX or DX which indicates a single strand connector or dual strand connector.

The following are examples of connectors and their designations.

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Fiber Optics

Three of the most commonly used fiber connectors:

SC

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Fiber Optics

The ST (straight tip connector) historically has been the most commonly used connector in the industry up to several years ago, it was not originally recognized by the standards but was added because of it’s prevalence in the industry.

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Fiber Optics

The duplex SC (subscriber connector) was the first connector to be recognized by the TIA/EIA fiber standards because of it’s ease of interconnectablity and it represents a complete link (1 connector for TX the other for RX).SC/PC MM DX CONNECTOR SC/PC SM DX CONNECTOR

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Fiber Optics

The SC single and duplex version, this was the defacto standard for all LAN terminations and is still used today.

SC CONNECTORS

SC/APC DX CONNECTOR

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Fiber Optics

The new standard in fiber connectors is the LC (Lucent connector). These are small form factor (SFF) connectors that take up less space in a fiber panel.

LC DX & SX MM PC

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Fiber Optics

A fiber connector designed for FTTD (fiber to the desk) is the MTRJ (mechanical transfer registered jack), as you can see this connector mimics an RJ-45 connector.

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Fiber Optics

Connectors that are no longer used but still may be installed in older cable plants:

FC FERRULE CONNECTOR

SMA BICONIC D4

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Fiber Optics

Another connector type used for WAN (wide area networks) is the FDDI (fiber distributed data interface) connector which is typically used on single mode fiber.

COUNTER ROTATING RINGS FOR FAULT TOLERANT NETWORKING

FDDI TOPOLOGY

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Fiber Optics

Here is a dissected view of a fiber connector

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Fiber Optics

900um buffered fiber can be connectorized. We can install a fiber connector directly onto the fiber strand.

250 or 500um buffered fiber can not be directly connectorized. We have to build up the outer jacket of the fiber strand.

To do this we use a breakout kit, fan out assembly or furcation tubing.

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Fiber Optics

Break out kits/fan out assemblies

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Fiber Optics

Furcation tubing is clear hollow tubing that comes in rolls.

The installer cuts them to length and slides the 250um fiber thru to build up the jacketing to 900um.

Where the furcation tubes meet the fibers loose tube, will require the appropriate heat shrink material to attach it all together.

This facilitates connectorization.

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Fiber Optics

This universal breakout kit provides the ability to install 1.2mm or 3.0mm furcation tube (jacket) over the 250um coated fibers from multi-fiber loose tube cables. Connectors then can be installed directly onto the 1.2mm or 3.0mm furcation tube.

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Fiber Optics

Small 250uM fibers are slid thru the tubes of a fan out kit to build up the outer jackets of the strands. This then allows us to install the connectors onto the strand.

There is a housing on the fan out kit that connects to the cable