We all know that information communication is inseparable from the transmission of optical fibers. Most people just know that there is a fiber optic thing, but they don't know the exact information. For example: What is fiber optics? What types are there? What is the working principle, etc., the following is a detailed introduction to you.
What is fiber optics?
Optical fiber, short for optical fiber, is a fiber made of glass or plastic that acts as a light-transmitting tool. The tiny fiber is encased in a plastic jacket that allows it to bend without breaking.
[Note here] There is a difference between an optical fiber and a fiber optic cable: an optical fiber is a thin, flexible medium that transmits a light beam. Optical fiber cables consist of a bundle of fibers, referred to as optical cables for short. The optical fiber is the core part of the optical cable, and the optical fiber constitutes the optical cable through the protection of some components and the auxiliary protective layer.
Fiber size
In a multimode optical fiber, the core diameters are two kinds, 50 μm and 62.5 μm, which are roughly equivalent to the thickness of a human hair. The diameter of the single-mode fiber core is 8 μm~10 μm, and 9/125 μm is commonly used.
Fiber Jumper
Types of optical fibers
Classification by transmission mode
According to the transmission mode of light in the fiber, it can be divided into multimode fiber (MMF) and single mode fiber. The central glass core under the multi-mode operation is relatively thick (50μm and 62.5μm), and can transmit light in multiple modes. However, its intermodal dispersion is relatively large, which limits the frequency of transmitting digital signals. Therefore, the transmission distance of multimode fiber is relatively short, generally only a few kilometers. The central glass core of a single-mode fiber is very thin (usually 9/125 μm), and can only transmit light in one mode. Therefore, its intermodal dispersion is very small, which is suitable for long-distance communication.
Classification by fiber material
According to the material of the optical fiber, the types of optical fibers can be divided into silica optical fibers and all-plastic optical fibers.
Silica fiber generally refers to an optical fiber composed of a doped silica core and a doped silica cladding. This fiber has very low loss and moderate dispersion. At present, the vast majority of communication fibers are silica fibers.
All-plastic optical fiber is a new type of optical fiber for communication, which is still in the development and trial stage. All-plastic fiber has the characteristics of large loss, thick core (100-600μm in diameter), large numerical aperture (NA) (generally 0.3-0.5, which can be coupled with light sources with large spot) and low manufacturing cost. Currently, all-plastic optical fibers are suitable for shorter-length applications such as indoor computer networking and communications within ships.
Classification by fiber profile refractive index distribution
According to the different refractive index distributions of the optical fibers, the types of optical fibers can be divided into step fibers and graded fibers.
Fiber interface type
1: FC type optical fiber connector: the external strengthening method is a metal sleeve, and the fastening method is a turnbuckle. Generally used on the ODF side (the most used on the patch panel);
2: SC-type optical fiber connector: the connector for connecting the GBIC optical module, its outer shell is rectangular, and the fastening method is the plug-and-pull type, which does not need to be rotated. (mostly used on router switches);
3: ST-type optical fiber connector: commonly used in optical fiber distribution frame, the outer shell is round, and the fastening method is turnbuckle. (For 10Base-F connections, the connectors are usually ST type. Often used in fiber optic distribution frames);
4: LC-type fiber optic connector: a connector for connecting SFP modules, which is made with a modular jack (RJ) latch mechanism that is easy to operate. (commonly used by routers);
5: MT-RJ: a square fiber optic connector with integrated transceiver, one double fiber transceiver integrated;
How Fiber Optics Work
Light is transmitted in the core part of the fiber by "total internal reflection", that is, after entering one end of the fiber, light is reflected back and forth between the interface between the core and the cladding, and then transmitted to the other end of the fiber. A fiber with a core diameter of 62.5 μm and a cladding outer diameter of 125 μm is called 62.5/125 μm light.
Fiber Applications
In addition to the well-known application of optical fiber in communication transmission, what other applications can it be used in?
communication application
Optical fibers can be used in communication technology.
medical application
Fiberoptic endoscopes can be introduced into the heart and ventricles to measure blood pressure in the heart, oxygen saturation in the blood, body temperature, etc.
sensor application
Optical fibers can send sunlight to all corners and can also be mechanically processed. Computers, robots, automotive switchboards, etc. have also successfully used optical fibers to transmit light sources or images.
art application
Due to the good physical properties of optical fibers, fiber optic lighting and LED lighting have increasingly become the use of art decoration and landscaping.
Downhole Detection Technology
Fiber Transceiver
Optical fiber transceiver is an Ethernet transmission media conversion unit that interchanges short-distance twisted-pair electrical signals and long-distance optical signals, and is also called an optoelectronic converter in many places. The product is generally used in the actual network environment where the Ethernet cable cannot cover and must use optical fiber to extend the transmission distance, and is usually located in the access layer application of the broadband metropolitan area network; at the same time, it helps to connect the last mile of optical fiber to the metropolitan area. It also plays a huge role on the Internet and beyond.
