B) What are the types of optical fiber docking technologies? What kind of equipment is needed and what is the price?

1. Main modes of optical fiber connection 1. Fixed connection. It is mainly used for permanent connection between optical fibers in optical cable lines, mostly welding, bonding and mechanical connection. It is characterized by low joint loss and high mechanical strength. The equipment needs a welding machine, about tens of thousands of RMB 2. Active connection. It is mainly used to connect optical fiber and transmission system equipment and instruments, mainly through optical connection plugs. Its characteristics are better flexibility of joints, convenient replacement of connection points, and great loss and reflection, which are the shortcomings of this connection method. Now the insertion loss is also very good, tens of RMB is enough, and you can buy the finished product directly. If you want parts, you need end polishing equipment, which is too expensive. It is recommended to buy jumpers directly. 3. Temporary connection. This method is generally used to measure the coupling connection between the pigtail and the measured optical fiber. Its characteristics are convenience, flexibility, low cost and low requirement for loss. This method is often used for temporary measurement. It can also be bonded by welding machine or V-groove. 2. Requirements for optical fiber connection 1. Optical fiber fixed connection is a key technology of optical cable line. The requirements for fixed connection are: low connection loss and good consistency; The connection loss is stable, and there should be no additional loss in the general temperature difference range; Have sufficient mechanical strength and service life; The operation should be as simple as possible to facilitate the construction; The size of the joint should be small, which is convenient for placement and protection; Low cost and easy processing of materials. 2. Requirements for movable connection At present, mechanical connectors are used to realize detachable optical fiber connection. Main requirements: the connection loss should be small, the loss of single-mode fiber should be less than 0.5 dB, and it should have good repeatability and interchangeability. After plugging and unplugging interchangeable parts for many times, there is still good consistency; Good stability, stable insertion loss of the connector after fastening, not affected by temperature change; Small size and light weight; Have a certain strength; The price is right. 3. Requirements for temporary connection The temporary connection of optical fiber can also be welded by welding machine. It is required that the loss be as low as possible. When connecting the V-shaped groove with the capillary tube, the proportioning liquid must be added, otherwise the Fresnel reflection cannot be eliminated. 3. Factors causing the loss of optical fiber connection: After the optical fiber is connected, the light passing through the joint will produce a certain loss, which is called the transmission loss of optical fiber connection, that is, the joint loss. This paper mainly analyzes the factors that cause the connection loss of single-mode optical fiber. 1. Mode field diameter is the single-mode fiber with the greatest influence on connection due to inherent factors. When the mode field diameter mismatch is 20%, the loss will exceed 0.2 dB. It is of great significance to use optical fiber with smaller mode field diameter as much as possible to reduce the connection loss. 2. The main external factors that cause the connection loss of single-mode fiber are axial misalignment and axial tilt. For mechanical connection, there are also factors such as longitudinal separation and core deformation. (1) axis is misaligned. When the misalignment reaches 1.2μm, the loss can reach 0.5 dB, which improves the accuracy of connection positioning and can effectively control the influence of axis misalignment. (2) axial tilt. When the tilt reaches 1, it will cause a loss of 0.2 dB. Choosing high quality fiber cutter can improve the loss caused by axial tilt. (3) core deformation. When the current, propulsion, discharge current and time of automatic welding machine are set reasonably, the loss caused by iron core deformation can be below 0.02 dB. 4. The methods and comparison of optical fiber connection 1. Welding machine welding this method is mainly used for the connection of optical fiber connectors. At present, it is mostly used in automatic welding machine for welding. Welding machines are divided into single-core and multi-core welding machines. Before the formal splicing, the parameters of the splicer should be tested to determine the alignment accuracy, discharge amount, propulsion amount and other parameters of the splicer, so as to adapt it to the specific working conditions of the specific spliced optical fiber and control the loss within the set index. After the connection is completed, the optical time domain reflectometer should be used to measure the loss in time. When the loss meets the index requirements, it can be reinforced until the connection is completed. 2. Mechanical connection The connection characteristics of the three most common mechanical connectors at present are as follows: FO process connector. This kind of optical fiber connector is the standard connection form of single-core optical fiber. At present, most products polish the end face into a spherical shape, and use the principle of optical refraction to converge the light beam to reduce its connection loss. This kind of optical fiber connector is mostly used to exchange between optical fiber distribution frame and test bench. NTT multi-core optical fiber connector. This optical fiber connector can connect as many as 12 optical fibers at a time, and has the characteristics of large capacity, simple manufacturing process and low connection loss. Therefore, it is widely used in optical fiber connection of users with low requirements. This method is mostly used in optical fiber short-distance relay and user relay, and the effect is good. Wire connector. With the development of technology, the average connection loss of connectors can be below 0. 1 dB, and the joint loss of 50% can be below 0.05 dB, and the adaptability to environmental temperature and humidity is also excellent. Because this connection method does not need expensive welding machine, and has many specifications such as single core and multi-core, it is flexible and convenient to use, and its application prospect is expected to be broader and wider, making the connection of optical fiber as convenient as cable. In the development of optical fiber communication, connection technology is a key technology. Simplifying splicing process and improving splicing quality will play a positive role in expanding the application field of optical fiber.