Introduction editor
A device for repeatedly plugging and unplugging optical fibers, also known as a fiber optic active connector. The main performance parameters ( and typical values ) are insertion loss ( < 0.5 db ), insertion / removal repeatability and interchangeability between connectors ( 500 changes ). Small reflections are also required for high-capacity high-speed transmission systems.
Classified editing
Introduction
Optical fiber connectors can be divided into single-mode and multi-mode connectors for common silicon-based optical fibers according to the transmission medium, and others such as plastic
Splice principle of optical fiber connector
Splice principle of optical fiber connector
An optical fiber connector in which glue or the like is a transmission medium; According to the connector structure form can be divided into: fc, sc, ST, LC, D4, din, mu, mt and so on various forms. Among them, ST connector is usually used for wiring equipment, such as fiber distribution frame, fiber module, etc.; Whereas sc and mt connector are typically used on that network device side. Fc, PC ( including SPC or UPC ) and APC are divided according to the shape of the fiber end face; There are also single-core and multi-core ( e. g., mt - rj ) division by fiber core count. Fiber optic connectors are widely used and have many varieties. In practical application, we usually distinguish the optical fiber connector according to its structure. Here are some of the fiber optic connectors that are now common:
Fc type optical fiber connector
The connector was first developed by ntt in Japan. Fc is the abbreviation for ferrole connector, indicating that it is externally reinforced with metal sleeves and screwed. First, fc - type connectors used a flat contact ( fc ) with the mating end face of the ceramic pins. The connector is simple in structure, convenient to operate and easy to manufacture, but the fiber end is sensitive to dust, fresnel reflection is easy to generate, and it is difficult to improve the performance of return loss. Later, this type of connector was improved by using a pin ( PC ) with a spherical butt end, while the external structure was not changed, so that the insertion loss and return loss performance were greatly improved.
Sc type optical fiber connector
This is a fiber optic connector developed by ntt corporation of Japan. The outer shell is rectangular, and the structural dimensions of the pin and the coupling sleeve are exactly the same as those of the fc type. Wherein the end face of the pin is mostly in a PC or APC type grinding mode; The fastening mode is plug pin latch type, do not need to rotate. The connector is low in price, convenient to plug and insert, low in fluctuation of interference loss, high in compressive strength and high in installation density.
St and sc interfaces are two types of fiber optic connectors, typically ST for a 10 base - f connection and sc for a 100ba se - FX connection. The core of the ST connector is exposed and the core of the sc connector is in the connector.
Double cone connector ( b icon connector )
The most representative product of this type of fiber optic connector was developed by bell laboratory and consists of two precision molded cylindrical plugs with frusto - conical ends and a coupling assembly with a double tapered plastic sleeve inside. Din 47256 fiber optic connector this is a connector developed by Germany. The pin and coupling sleeve used in this connector have the same structure size as fc type, and the end face treatment adopts PC grinding method. Compared with fc connector, its structure is more complex, the internal metal structure has a spring to control the pressure, can avoid because of excessive plug pressure and damage the end face. In addition, the mechanical precision of the connector is high, and therefore the intervention loss value is small.
Mt - rj connector
Mt - rj started with ntt - developed mt connectors with the same latching mechanism as rj - 45 LAN electrical connectors, aligned with optical fibers via guide pins mounted on both sides of the mini - ferrule. for ease of connection with optical transceivers, the connector end-face optical fibers are dual-core ( 0.75 mm apart ) array design and are the next generation of high-density optical fiber connectors primarily used for data transmission.
Lc type connector
Lc - type connector is developed by bell research institute, and is made of modular jack ( rj ) latch mechanism which is easy to operate. The size of the pins and sleeves used therein is one half of the size used for conventional sc, fc, and the like, and is 1.25 mm.. This increases the density of the fiber optic connectors in the fiber optic distribution frame. At present, LC - type connectors have actually taken a dominant position in single-mode SFF, and their applications in multimode are growing rapidly.
Mu connector
The mu ( minimum unit coupling ) connector is the world's smallest single-core fiber optic connector developed by ntt, based on the sc connector that is currently the most widely used. The connector uses a 1.25 mm diameter sleeve and a self-retaining mechanism, with the advantage that a high density installation can be achieved. Ntt has developed a series of mu connectors using mu's l 25 mm diameter bushings. They have socket-type connectors ( mu - a series ) for optical cable connections; Floor connector ( mu - b series ) with self-retaining mechanism and simplified socket ( mu - Sr series ) for connecting LD / PD module and plug, etc. With the rapid development of optical fiber network towards larger bandwidth and larger capacity, and the wide application of DWDM technology, the demand for mu connector will increase rapidly.
Mc connector
In 2012, the domestic communication company independently developed a MC connector with smaller volume and higher density than LC connector. Tianhai MC fiber optic active connector is a high density single core fiber optic active connector, suitable for various high density occasions, such as large capacity center room and high density data center. The MC fiber optic active connector has a high density and can be up to twice as high as the LC connector in the same space, making it the smallest and highest density connector in the world.
Mc fiber optic connector
Mc fiber optic connector
Main parameters:
Mc / UPC
Insertion loss ( typical )
≤ 0.30 db
Insertion loss ( random )
≤ 0.50 db
Return loss
Greater than or equal to 40 db
Mc / APC
Insertion loss ( typical )
≤ 0.30 db
Insertion loss ( random )
≤ 0.50 db
Return loss
60 db or more
Other
Fibre connectors can also be referred to as ficon - fibre connector's IBM mainframe channel launched in 1998 with G5 servers. Based on the fibre channel standard, it increases escon's half-duplex 17mb / s transmission rate to 100 MB / s full duplex. Each ficon channel can support up to 4000 I / o operations per second, equivalent to 8 escon channels.
General structure editor
The main purpose of the optical fiber connector is to realize the connection of the optical fiber. Optical fiber connectors, which are widely used in optical fiber communication systems, have many kinds and different structures. But in detail, the basic structure of the various types of fiber optic connectors is consistent, that is, the vast majority of fiber optic connectors generally use high precision components ( composed of two pins and a coupling tube of three parts ) to achieve the alignment of the optical fiber connection.
In this method, the optical fiber is inserted into and fixed in the pin, and the surface of the pin is polished to realize alignment in the coupling tube. The outer component of the pin is made of metal or non-metal material. The butt end of the ferrule must be ground, and the other end typically uses a bend limiting member to support the optical fiber or fiber optic flex cable to relieve stress. Coupling tube is generally made of ceramic, or bronze and other materials made of two and a half synthetic, fastening cylindrical member, more equipped with metal or plastic flange, in order to facilitate the installation of the connector is fixed. In order to align the optical fiber as accurately as possible, the machining accuracy of the pin and coupling tube is very high.
Performance editing
The performance of the optical fiber connector, the first is the optical performance, in addition to considering the interchangeability of optical fiber connector, repeatability, tensile strength, temperature and plug times, etc.
( 1 ) optical performance: the optical performance requirements of the optical fiber connector are mainly the insertion loss and return loss, which are the two most basic parameters.
Insertion loss, or connection loss, refers to the loss of link effective optical power caused by the introduction of the connector. The smaller the insertion loss, the better, the general requirement should not be greater than 0.5 db.
Return loss ( reflection loss ) refers to the connector's ability to suppress link optical power reflection, its typical value should not be less than 25 db. In practical connector, the surface of pin has been polished specially, which can make the return loss larger, generally not less than 45db.
( 2 ) interchangeability and repeatability
Fiber optic connectors are common passive devices and can generally be used in any combination and repeatedly for the same type of fiber optic connectors, whereby additional losses introduced are generally in the range of less than 0.2 db.
Fiber optic connector
Fiber optic connector
( 3 ) tensile strength
For a good fiber optic connector, the tensile strength is generally required to be not less than 90 n..
( 4 ) temperature
It is generally required that the fiber optic connector be capable of normal use at temperatures of - 40oc to + 70oc.
( 5 ) plug number
The fiber optic connectors used today can be plugged or unplugged more than 100 times.
Annotation interpretation: we can often see " fc / PC", " sc / PC" and so on in the annotation of the tail fiber connector, which has the following meanings:
The front part of " /" indicates the connector model of the pigtail, as described above. " /" later said optical fiber joint section process, namely grinding mode. There are three ways to contact the end face of optical fiber connector: PC, UPC and APC. < figure slightly > PC - physic contact, the original intention is the meaning of physical contact, pin body end face for physical end face; Upc - ultra physical contact, pin body end face for super physical end face; Apc type - angle physical contact, the end face of the pin body is an angle physical end face; The difference between the three in addition to the physical is not the same, and return loss, namely reflection loss ( performance ) is not the same. Pc < UPC < APC. Multimode fiber does not have APC type. " PC" is the most widely used equipment in telecom operators, its joint section is flat. The decline of UPC
Performance of fiber optic connectors
Performance of fiber optic connectors
Consumption is smaller than " PC", generally used for equipment with special needs, some manufacturers optical connection equipment internal jumper is fc / UPC, mainly in order to improve the indicators of the equipment itself. " APC" is used in radio and television and early CATV system, because APC uses the end face with tilt angle, can improve the quality of the TV signal, the main reason is that the TV signal is analog light modulation, when the joint coupling surface is vertical, reflected light along the original path back. Due to the uneven distribution of optical fiber refractive index will return to the coupling surface again, at this time although the energy is very small, but because the analog signal is unable to completely eliminate noise, so equivalent to the original clear signal superimposed on a weak signal with delay, performance is ghosting on the picture. The angle of inclination of that pigtail headband prevent reflected light from return along the original path. This problem generally doe not exist with general digital signals.
Domestic situation editor
At present, with the continuous development of domestic communication, optical fiber communication has entered a practical stage, and the scope of application is more and more wide. Our country now for optical fiber connector used in optical communication system, or use imported connector, or to import the ceramic sleeve and peripheral metal parts and other so-called " parts" in the domestic assembly, or according to the introduction of foreign technology and key equipment for production, mainly fc type optical fiber connector. In view of this situation, the author suggests the following.
( 1 ) standardization
There are many types and standards of optical fiber connector products in the world. if they are introduced and used without restriction, there will be confusion and inconvenience for maintenance and management. According to the introduction, in this respect, the United States, Japan, Germany, France and other countries have national standards, and approved by the iec; My country has similar provisions in this regard. It is recommended that such provisions be published in the form of national standards as part of technical documents such as technical specifications or access requirements.
( 2 ) compatibility issues
As communication is a system engineering, it is recommended that the user should consider the compatibility of optical fiber connectors used in optical transmission equipment, optical accessory equipment, optical test instruments and other items when ordering. On the basis of not affecting the performance of the system, the instrument equipment to be ordered shall be as consistent as possible with the model of the optical fiber connector of the existing instrument. If not, consider the problems that may arise during use and order or prepare the appropriate transfer flange or patch cord.
( 3 ) production and use problems
In terms of production, it is recommended that the state guide the manufacturers of optical fiber connectors according to the relevant provisions and combined with the domestic existing and use situation, unified on the basis of a core component ( such as phi 2.5 mm pin and corresponding sleeve ) development in line with the national conditions, adapt to the needs of the product.
In terms of use, it is recommended that the user should choose the appropriate fiber optic connector according to their actual situation. On the premise of meeting the system requirements, fully consider the relationship between performance, price and development, and strive to reduce costs and expand the scope of use. In the future optical fiber user network and high-speed local area network, price and hardware upgrade and other issues may be more prominent, users need to consider the performance, price and development.