Optical fiber communication technology
As a communication signal, light has existed since ancient times. From the ancient Beacon Tower to the current traffic lights, this simple way of using light to transmit information is still widely used. The evolution of civilization in human society and the development of science and technology continue to promote the in-depth application of light in all walks of life. Optical fiber communication technology, as an important symbol of the world's new technology revolution, is an important tool for today's social information transmission. It mainly uses light waves as carrier waves, and uses optical fibers as transmission media to transfer information from one place to another. Optical fiber communication technology includes fiber optic cable technology, optical switching technology, transmission of only small, optical active devices, optical passive devices, and optical network technology.
In 1966, British Chinese scholar Gao Qi published an epoch-making paper. He proposed the theory of using quartz glass optical fiber with cladding material as a communication medium and described the requirements for long-distance, large-information optical communication. Optical fiber structure and material characteristics. The 85-micron-band multimode optical fiber communication system that emerged in 1977 was the first-generation optical fiber communication system; the communication system for 1.3-micron multimode fiber that was implemented in 1981 was the second-generation fiber-fiber communication system; the 1.3-micron single-mode that was implemented in 1984. The fiber optic communication system is a third generation fiber optic communication system; the 1-55 micron single mode fiber optic communication system implemented in the mid to late 1980s is a fourth generation fiber optic communication system. With the continuous development of optical fiber technology, the transmission capacity of optical fiber communication systems has also increased nearly 10,000 times from 1980 to 2000, and the transmission speed has increased by about 100 times in the past 10 years.
Since the advent of optical fiber communications, it has brought a revolution to the entire communications field. The characteristics of optical fiber communications are mainly reflected in several aspects.
1. Large transmission bandwidth and great communication capacity
The transmission bandwidth of optical fiber is much larger than that of copper cables. Currently, the transmission rate of single-wavelength optical fiber communication systems is in the range of 2.5 Gb/s to 10 Gb/s. For a single-wavelength optical fiber communication system, due to the electronic bottleneck effect of the terminal device, the advantage of large optical fiber bandwidth cannot be exerted. A variety of complex techniques are commonly used to increase the transmission capacity. In particular, the current dense wavelength division multiplexing technology greatly increases the transmission capacity of the optical fiber.
2. Strong anti-electromagnetic interference
Optical fiber raw materials are generally quartz, corrosion resistance, insulation, not subject to the natural lightning, ionospheric changes and sunspot activity interference, but also not artificially released electromagnetic interference. It is a non-conductive medium in which alternating electromagnetic waves do not generate induced electromotive force, ie, noise that is not related to the signal is not generated. It is laid in parallel to high-voltage wires and electric railways, and is not subject to electromagnetic interference. This is particularly advantageous for communication systems in the field of high-power systems such as power transmission lines and electrified railways. Due to its strong anti-interference ability, it is also widely used in the military field.
3 low loss, long relay distance
The optical fiber system is mostly quartz optical fiber, and the loss of quartz optical fiber can be lower than 0.20dB/km. The transmission loss of this kind of optical fiber is lower than that of any other transmission medium. Therefore, the distance of the optical fiber communication system composed of it is also Systems that are longer than other media are much longer. With the development and application of technical materials, the use of ultra low loss transmission media in the future will also reduce this loss to a lower level.
4. No crosstalk, good confidentiality
Electromagnetic waves are easily leaked during the propagation process, so their confidentiality is poor. While light waves propagate in the fiber, crosstalk does not occur, and confidentiality is relatively stronger.
It is because of the many advantages of fiber-optic communications that it was first applied in the power sector and rapidly developed. Nowadays, in addition to ordinary fiber optic applications, fiber optic technology is also widely used in telecommunications, industrial inspection, aerospace, limited television networks, and intelligent hardware transmission. Take the television network, the television network adopting the broadband digital transmission system composed of SDH+ optical fiber or ATM+ optical fiber can meet the needs of various comprehensive information transmission. At present, CATV in many regions is already an optical fiber transmission. In the era of Internet TV, the fiber/household project has been fully opened.
Optical transmission network technology
Optical transmission network technology mainly refers to the technology of transmission between the transmitter and the receiver in the form of optical signals. It is simply a technology that uses optical fiber as a transmission medium and uses optical fiber as a transmission medium. From 1966, Takahashi proposed a light transmission barrier, and by 1976, optical transmission practical products came into use. By the 1980s, the PDH (Synchronous Digital Transmission System) application was upgraded to the SDH standard in the 1990s. The dense wavelength-division multiplexing system (DWDM) that began construction began in 2002, and the optical add-drop multiplexer system (OADM), optical cross-connect system (OXC), and intelligent optical network (ION) emerged after 2002.
After decades of development, optical transmission technology has far exceeded the concept of initial SDH circuit crossover and WDM wavelength connection. The MSTP proposed in 2000 and the gradual commercialization of ASON in recent years have become a popular optical network technology for communication transmission. Studying optical transmission network and optical network technology to meet the growing demand of mobile communication networks, building a new basic transmission network, improving the competitiveness of the entire business, and forming a full-service camp has very important practical significance.
Optical fiber transmission system is mainly composed of three expansions, and mouth light source (also known as optical transmitter), transmission medium and detector (also known as optical receiver). In optical fiber transmission between computer networks, the work of the light source and the detector is generally completed by a fiber transceiver. The fiber transceiver is simply a device for implementing twisted pair and optical fiber connection. Its role is to twist the twisted pair. The transmitted signal is converted into a signal (optical signal) that can be transmitted through the optical fiber.
The advantages of fiber-optic transmission and fiber-optic communications are similar. They also have the characteristics of large transmission bandwidth, anti-jamming, and large amount of information transmission. In addition, since the transmission of the communication signal in the optical fiber is transmitted in the form of light, it does not cause sparks or static electricity due to a short circuit or a bad contact of the conventional wire, and it can ensure the safety of use and the safety of the equipment. At the same time, due to the slenderness of the fiber, the weight and outer diameter of the fiber will not increase as much as normal cables. Even if a multi-fiber cable is used, its weight will not increase too much. The most important point is that the confidentiality of transmission of optical signals in optical fibers will be more than 100 times that of conventional cables and cannot be eavesdropped by people.
The application of optical transmission is also widely used in various fields such as power systems, communication systems, closed-circuit television monitoring systems, and security monitoring systems.
The photoelectric switch is the abbreviation of the photoelectric proximity switch. It utilizes the shielding or reflection of the light beam by the detected object, and the circuit is connected by the synchronization loop to detect the presence of the object. The object is not limited to metal, all objects that can reflect light (or block light) can be detected.
Photoelectric Proximity Sensor,Photoelectric Switch Sensor,Photoelectric Proximity Switch,Infrared Photoelectric Switch Sensor
Changchun Guangxing Sensing Technology Co.LTD , https://www.gx-encoder.com