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About the function, structure and characteristics of optical fiber connectors


Optical fiber connectors are divided into optical fiber fixed connectors, that is, fixed connections between the relay sections. The methods of fixing the joints include the fusion welding method, the V-groove method, the capillary method, and the sleeve method. Optical fiber connector, commonly known as a live joint, generally known as optical fiber connector, is between the optical fiber line and the equipment

Removable connection.

The function of optical fiber active connector and adapter

(1) It can form a continuous optical path

(2) Repeatable loading and unloading

(3) Active connection with active or passive devices

(4) Active connection with system and instrument

It is widely used in long-distance trunk network, metropolitan area network, access network, optical fiber CATV network, optical fiber data network, DWDM system, and other optical communication, optical sensor, and other optical fiber applications.

The basic principle of the fiber optic connector is to use a certain mechanical and optical structure, and use the adapter to accurately butt the two end faces of the optical fiber to achieve physical contact between the fiber end faces. So that the optical energy output by the transmitting fiber can be coupled into the receiving fiber to the maximum extent.

Take FC / PC optical fiber connector and FC / PC as examples, as shown in the figure below:

The connector can be divided into three parts according to the structure

1) Ceramic ferrule

2) Connection structure (composed of parts)

3) Fiber optic cable

Characteristics of fiber optic connectors:

1) Insertion loss

Refers to the decibel ratio of the output optical power to the input optical power after the optical signal in the optical fiber passes through the connector, and its expression is: IL = -10Log

Where-optical power at the output

-Input optical power

The smaller the insertion loss, the better. The general requirement should not be greater than 0.3dB. For multimode fiber connectors, the injected optical power should pass through the mode stabilizer to filter out higher-order modes, so that the modes in the fiber are distributed in a steady-state, and the test loss is more accurate.

2) Return loss, that is a backward reflection loss. It refers to the decibel ratio of the retro-reflected light to the input light at the fiber connection, and its expression is = -10Log-back-reflected optical power-input optical power

The greater the return loss, the better, to reduce the impact of reflected light on the light source and system. In actual connectors, the pin surface has been specially polished to make the return loss larger, generally not less than 45dB.

3) Repeatability

Refers to the change in insertion loss of an optical fiber (cable) active connector after multiple insertions and withdrawals, expressed in dB.

4) Interchangeability

This refers to the change in insertion loss when the components of the connector are interchanged, and is also expressed in dB. These two indicators can assess the rationality of connector structure design and processing technology and are also important indicators that indicate the practicality of connectors.

5) Mechanical properties

The mechanical properties of optical fiber connectors include axial retention strength, termination retention force, connection and separation force (torque), impact, torsion, cable retention force, anti-extrusion, external bending moment, vibration, impact, static load, etc. The requirements of different fiber optic connectors are different, and the requirements are different.

Mechanical durability refers to the number of insertion and removal of optical fiber connectors under normal use. Currently used optical fiber connectors can generally be inserted and removed more than 1,000 times.

6) Environmental performance

Environmental performance mainly includes high temperature, temperature shock, humidity, sand and dust, ozone exposure, corrosion (salt spray), flammability, etc.