Quotation - Zhihu - 【Dongguan Zhaoheng Machinery】

Currently, with the continuous development of the domestic communication industry, optical fiber communication has entered the practical stage and its application scope is becoming wider and wider. At the same time, it has put forward more and higher requirements for optical fiber connectors. The main development direction is to make the appearance smaller and the cost lower, while the requirements for performance are getting higher and higher. The following will explain the differences between pre-buried optical fiber and non-pre-buried (straight-through) optical fiber connectors, optical fiber jumpers, and tail fibers.

The differences between pre-buried optical fiber quick connectors and straight-through connectors

Optical fiber quick connectors are divided into two major categories based on the technology used: pre-buried optical fibers and non-pre-buried (straight-through) optical fiber connectors. The main differences lie in the connection points and connection methods:

(1) Connection point setting

The connection point of pre-buried optical fibers is set inside the connector. Pre-buried optical fibers have pre-applied matching liquid. The connection point of non-pre-buried (straight-through) optical fibers is on the surface of the connector. No matching liquid is pre-applied and the connection is directly achieved through an adapter with the target optical fiber.

(2) Connection method

Optical fiber quick connectors insert and fix the optical fibers in the pins and then polish the surface of the pins. Alignment is achieved in the coupling tube. The outer components of the pins are made of metal or non-metal materials. The mating end of the pins must be ground. The other end usually uses a bending restraint component to support the optical fiber or optical flexible cable to release stress. The coupling tube is generally a semi-closed cylindrical component made of two halves of ceramic or bronze materials, often equipped with metal or plastic flanges for easy installation and fixation of the connector. To achieve precise alignment of the optical fibers, high processing accuracy is required for the pins and the coupling tube.

Straight-through optical fiber quick connectors have no pre-buried optical fibers or matching gel inside. After the optical fibers are clamped, the fiber end can be inspected with a magnifying glass to avoid excessive fiber connection loss. The axial positioning mechanism is provided, and during the clamping process, the optical fiber will not move axially forward.

The differences among optical fiber patch cords, tail fibers, and optical fiber connectors

(1) An optical fiber patch cord is used as a jumper line from a device to the optical wiring link. It has a thicker protective layer and is generally used for connection between optical transceivers and terminal boxes.

(2) A tail fiber, also known as a pigtail cable, has a connector at one end and a severed end of an optical fiber core at the other end. It is connected to other optical fiber cores through fusion splicing and is often found in optical terminal boxes. It is used to connect optical fibers and optical transceivers (couplers, patch cords, etc. are also used in between).

An optical fiber connector is a device that enables a detachable (active) connection between optical fibers. It precisely aligns the two end faces of the optical fibers to maximize the coupling of the optical energy emitted by the transmitting fiber into the receiving fiber, and to minimize the impact on the system caused by its involvement in the optical link. This is the basic requirement for an optical fiber connector.

To a certain extent, optical fiber connectors also affect the reliability and various performance of the optical transmission system. First, the optical cable enters from the outside. The optical cable needs to be fused in the optical cable box, which is what you call the terminal box. The fusion of the optical cable is a technical process. The optical cable needs to be stripped, and the tail fibers are fused with the fine fibers in the optical cable. After the fusion is completed, it is placed in the box. Then the tail fiber is exposed. The head of the optical fiber is connected to the ODF (a rack that uses couplers for connection). The other side of the rack also uses tail fibers (or optical fiber jumper cables can be said, but in fact, tail fibers are used for optical fiber jumper cables). It is connected to the optical-electrical converter, and the optical-electrical transceiver is connected to the network cable to connect to the router - switch - local area network - host.

In the above steps, the fiber distribution frame can be ignored. After the tail fiber comes out, it can be directly connected to the optical transceiver. Thus, the coupler is not necessary. The coupler is used to couple the two tail fibers (the thing that connects the optical fiber jumpers together). The optical coupler is used for the active connection of two optical fibers or tail fibers. It is commonly called a flange optical terminal box. It has one end as the optical cable and the other end as the tail fiber, which is equivalent to splitting a single optical cable into individual optical fibers. The optical fiber fusion splicing box is used to connect two optical cables into a long optical cable. They cannot be used interchangeably. The optical cable and the optical transceiver are connected through the optical terminal box, which means that the optical transceiver can only insert the tail fiber. Can the terminal box and the fusion splicing box be understood in this way? Are the terminal box and the fusion splicing box the same? No, they are different. The terminal box is fully sealed and can be waterproof, but it cannot fix the tail fiber. The terminal box is not waterproof. The internal structure has one side that can fix the optical cable and the other side that can fix the tail fiber. The coupler is used to connect optical fibers or tail fibers, but the connection part is movable, not fused. The coupler can only connect two tail fibers and has interfaces such as SC/PC, FC/PC, etc., while the optical cable and tail fibers are fused using a fusion splicer.

What are the differences between tail fibers and patch cords? Can a patch cord be split in half and used as a tail fiber?

Tail fibers have only one active connector at one end, while patch cords have active connectors at both ends. There are many types of interfaces, and different interfaces require different couplers. Splitting a patch cord in half can be used as a tail fiber. We do this. One end with a connector is called an optical fiber jumper, and the middle fiber is usually three meters long. It is used to connect couplers and optical transceivers, optical modules, or directly connect two devices with optical ports. The one with only one connector and a small section of fiber at the back is a tail fiber. Usually, two identical connectors of optical fiber jumpers are used, and the middle part is cut into two tail fibers. They are mainly used for fusion splicing onto optical cables. After fusing the tail fiber connector onto the optical cable, it can be connected to a coupler or directly connected to an optical transceiver or optical module. An optical connector should be the coupler (flange), which is used to connect tail fibers and patch cords.