Оптикалық талшық қосылғыштары: түрлері мен қолданылуы

Device used to join fiber optic strands in communication systems

An optical fiber connector is a device used to link optical fibers, facilitating the efficient transmission of light signals. An optical fiber connector enables quicker connection and disconnection than splicing. They come in various types like SC, LC, ST, and MTP, each designed for specific applications. In all, about 100 different types of fiber optic connectors have been introduced to the market. These connectors include components such as ferrules and alignment sleeves for precise fiber alignment. Quality connectors lose very little light due to reflection or misalignment of the fibers. Optical fiber connectors are categorized into single mode and multimode types based on their distinct characteristics. Industry standards ensure compatibility among different connector types and manufacturers. These connectors find applications in telecommunications, data centers, and industrial settings.

Optical fiber connectors are used to join optical fibers where a connect/disconnect capability is required. Due to the polishing and tuning procedures that may be incorporated into optical connector manufacturing, connectors are often assembled onto optical fiber in a supplier's manufacturing facility. However, the assembly and polishing operations involved can be performed in the field, for example, to terminate long runs at a patch panel. Optical fiber connectors are used in telephone exchanges, for customer premises wiring, and in outside plant applications to connect equipment and fiber optic cables, or to cross connect cables. Most optical fiber connectors are spring loaded, so the fiber faces are pressed together when the connectors are mated. The resulting glass to glass or plastic to plastic contact eliminates signal losses that would be caused by an air gap between the joined fibers. Performance of optical fiber connectors can be quantified by insertion loss and return loss. Measurements of these parameters are now defined in IEC standard 61753 1. The standard gives five grades for insertion loss from A (best) to D (worst), and M for multimode. The other parameter is return loss, with grades from 1 (best) to 5 (worst). A variety of optical fiber connectors are available, but SC and LC connectors are the most common types of connectors on the market. Typical connectors are rated for 500–1,000 mating cycles. The main differences among types of connectors are dimensions and methods of mechanical coupling. Generally, organizations will standardize on one kind of connector, depending on what equipment they commonly use. In many data center applications, small (e. g., LC) and multi fiber (e. g., MTP/MPO) connectors have replaced larger, older styles (e. g., SC), allowing more fiber ports per unit of rack space. Outside plant applications may require connectors be located underground, or on outdoor walls or utility poles. In such settings, protective enclosures are often used, and fall into two broad categories: hermetic (sealed) and free breathing. Hermetic cases prevent entry of moisture and air but, lacking ventilation, can become hot if exposed to sunlight or other sources of heat. Free breathing enclosures, on the other hand, allow ventilation, but can also admit moisture, insects and airborne contaminants. Selection of the correct housing depends on the cable and connector type, the location, and environmental factors.

Field mountable optical fiber connectors are used to join optical fiber jumper cables that contain one single mode fiber. Field mountable optical fiber connectors are used for field restoration work and to eliminate the need to stock jumper cords of various sizes. These assemblies can be separated into two major categories: single jointed connector assemblies and multiple jointed connector assemblies. According to Telcordia GR 1081, a single jointed connector assembly is a connector assembly where there is only one spot where two different fibers are joined together. This is the situation generally found when connector assemblies are made from factory assembled optical fiber connector plugs. A multiple jointed connector assembly is a connector assembly where there is more than one closely spaced connection joining different fibers together. An example of a multiple jointed connector assembly is a connector assembly that uses the stub fiber type of connector plug.

On all connectors, cleaning the ceramic ferrule before each connection helps prevent scratches and extends the connector life substantially. Connectors on polarization maintaining fiber are sometimes marked with a blue strain relief boot or connector body. Sometimes a blue buffer tube is used on the fiber instead. Hardened Fiber Optic Connectors (HFOCs) and Hardened Fiber Optic Adapters (HFOAs) are passive telecommunications components used in an outside plant environment. They provide drop connections to customers from fiber distribution networks. These components may be provided in pedestal closures, aerial and buried closures and terminals, or equipment located at customer premises such as a Fiber Distribution Hub (FDH) or an optical network terminal unit. These connectors, which are field mateable and hardened for use in the OSP, are needed to support Fiber to the Premises (FTTP) deployment and service offerings. HFOCs are designed to withstand climatic conditions existing throughout the U. S., including rain, flooding, snow, sleet, high winds, and ice and sand storms. Ambient temperatures ranging from 40 °C ( 40 °F) to 70 °C (158 °F) can be encountered. Telcordia GR 3120 contains the industry’s most recent generic requirements for HFOCs and HFOAs.

Glass fiber optic connector performance is affected both by the connector and by the glass fiber. Concentricity tolerances affect the fiber, fiber core, and connector body. The core optical index of refraction is also subject to variations. Stress in the polished fiber can cause excess return loss. The fiber can slide along its length in the connector. The shape of the connector tip may be incorrectly profiled during polishing. The connector manufacturer has little control over these factors, so in service performance may well be below the manufacturer's specification. Testing fiber optic connector assemblies falls into two general categories: factory testing and field testing. Factory testing is sometimes statistical, for example, a process check. A profiling system may be used to ensure the overall polished shape is correct, and a good quality optical microscope to check for blemishes. Insertion loss and return loss performance is checked using specific reference conditions, against a reference standard single mode test lead, or using an encircled flux compliant source for multi mode testing. Testing and rejection (yield) may represent a significant part of the overall manufacturing cost. Field testing is usually simpler. A special hand held optical microscope is used to check for dirt or blemishes. A power meter and light source or an optical loss test set (OLTS) is used to test end to end loss, and an optical time domain reflectometer may be used to identify significant point losses or return losses.