Optical Fiber Connectors

Optical fiber connectors are mechanical devices that are placed at the end of a fiber cable, allowing it to be connected to telecommunication equipment such as another cable, a receiver or a light source. They align the core of microscopic fibers together so light pulses can travel through them and allow communication. These devices make temporary links, which means they can be easily joined and detached.

Over the course of optical fiber technology development and improvement, several communication companies have created and introduced more than 100 connectors to the market, but just a few of them made it to the present days. And even fewer are considered the most used.

Optical Fiber Connectors Types

Optical fiber connectors Optical fiber connectors are used in premises installations, inside and outside plant applications, in CATV and telephony systems to join cables and equipment where a connect/disconnect capability is needed. Connectors are considered the weakest link in a fiber optic system, because they mark a spot in which signal power can be lost. So for optical fiber systems to have an outstanding performance, well designed connectors, good terminations and an installer with skills are needed.

There are several types of optical fiber connectors and they are all integrated by three main mechanisms:

The ferrule: This is the most important component of fiber optic connectors because it holds, protects and aligns the glass fiber. Ferrules are usually made of ceramic, high-quality plastic or metal. Of all those materials, zirconia ferrules are the ones that offer the highest performance and durability after several mating cycles.

Coupling mechanism: It keeps the connector in place when it is joined to another device. It could be push-pull or bayonet style.

Connector body: Is the structure that holds the ferrule, the coupling mechanism and the boot. It is made of plastic or metal.




Connectors’ end-face

The connectors’ end-face determines what the return loss, also known as back reflection, of a fiber optic cable will be. Return loss is the loss of power that happens when light returns from the fiber to the light source device due to discontinuities or airs gaps caused in the ferrule’s end-face. It is measured in decibels.

Ferrules are polished in different ways, which classifies connectors as:

- PC (Physical Contact): PC connectors are polished with a slight curvature, which reduces the air gaps between fibers. These connectors’ back reflection is between 30dB and 40dB.

- UPC (Ultra Physical Contact): UPC connectors also have a convex end-face, but have a finer surface finish. Their return loss goes from -40dB from -55dB, which makes them reliable for transmitting TV and data signals.

- APC (Angled Physical Contact): APC connectors have an 8° angle cut in their ferrules, which makes connections between optical fibers even tighter. Industry standards indicate that APC connectors back reflection is -60dB.

Source : http://www.networking-forum.com/viewtopic.php?f=24&t=48286