Cisco Systems OL-7861-01 manual Cleaning Fiber-Optic Connectors

Cabling and Specifications

Figure 42 Attaching Simplex or Duplex Fiber Cables (Line Card Port or GBIC)

Duplex

Simplex

FAST ETHERNET

TX

RX

22553

Simplex

Duplex

RX TX

17464

Note The fiber-optic connectors must be free of dust, oil, or other contaminants. Carefully clean the fiber- optic connectors using an alcohol wipe or other suitable cleanser.

Cleaning Fiber-Optic Connectors

Fiber-optic connectors are used to connect two fibers together. When these connectors are used in a communication system, proper connection becomes a critical factor. They can be damaged by improper cleaning and connection procedures. Dirty or damaged fiber-optic connectors can result in communication that is inaccurate or not repeatable.

Fiber-optic connectors differ from electrical or microwave connectors. In a fiber-optic system, light is transmitted through an extremely small fiber core. Because fiber cores are often 62.5 microns or less in diameter, and dust particles range from a tenth of a micron to several microns in diameter, dust and any other contamination at the end of the fiber core can degrade the performance of the connector interface where the two cores meet. Therefore, the connector must be precisely aligned and the connector interface must be absolutely free of foreign material.

Connector loss, or insertion loss, is a critical performance characteristic of a fiber-optic connector. Return loss is also an important factor. Return loss specifies the amount of reflected light: the lower the reflection, the better the connection. The best physical contact connectors have return losses of better than –40 dB, but –20 to –30 dB is more common.

The connection quality depends on two factors: the type of connector and the proper cleaning and connection techniques. Dirty fiber connectors are a common source of light loss. Keep the connectors clean at all times, and keep the dust plugs or covers installed when the connectors are not in use.

Before installing any type of cable or connector, use a lint-free alcohol pad from a cleaning kit to clean the ferrule, the protective tube or cone that surrounds the fiber core, and the end-face surface of the fiber core.

As a general rule, any time you detect a significant, unexplained loss of light, clean the connectors. To clean the optical connectors, use a CLETOP fiber optic cleaning cassette (Type A for SC connectors) and follow the manufacturer’s usage instructions.

If a CLETOP cleaning cassette is not available, follow these steps:

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