TLDR:在通信光缆中, light is introduced into the core of an optical fiber via a light source (LED, 激光二极管). The light rays reflect off the outer walls of the core (the cladding layer) until they reach the other end of the fiber where a light-传感 receiver converts the pulses into digital ones 和 zeros.
光纤通信电缆究竟是如何工作的?
At its most basic, a communications optical fiber cable is composed of 玻璃线，像线一样, 和人类头发的直径差不多, each of which can transmit messages modulated onto light waves at the speed of light. They offer greater b和width than copper wire cable 和 have become the go-to option to meet the dem和s of the age of the internet where large amounts of data (e.g., streaming apps) must be distributed to thous和s of subscribers, miles away 和 instantaneously. 光纤电缆不仅存在于 通信系统，它们也用于 工业网络, 传感, 航空电子设备的应用程序.
The first step to underst和ing how fiber optic works is to underst和 what happens when you send light through air or water. 光以波的形式传播. When it passes through the air, the wave loses some energy 和 becomes more spread out. The result is that the light beam gets wider 和 less intense. 这种强度的损失称为衰减.
When light enters the water, however, it does not lose any energy. Instead, it bends around the water molecules, making it easier for the light to pass through. Water also slows down the light’s velocity by a factor of 1/v2 where v is the speed of light in water. This means that light traveling through water will travel farther than if it were traveling through air. Optical fibers use these principles to carry data from one point to another.
Most optical fibers in use today consist of glass str和s (the core) 做的 pure silica surrounded by cladding material 做的 doped silica. The core is so small that only a single ray of light at a particular wavelength can travel through to the end. 这些被称为单模光纤. 在这个设计中, the cladding layer has a lower refractive index 和 acts like a mirror to keep the mode inside the core. 这种现象被称为全内反射.
The performance of optical fibers depends on how well they can transmit light. One way to measure this is by measuring the return loss (also called insertion loss) of the fiber. Return loss is defined as the ratio between the power in the forward direction 和 the power in the reverse direction. 如果回报损失高, more light will be lost when traveling through the fiber than if the return loss was low.
光纤电缆的优点
Optical fibers have many advantages over traditional copper wires:
1. Faster data transfer speeds: Fiber optic cables are able to carry much more information than traditional copper wires, 速度要快得多. 这使得它非常适合需要可靠性的应用程序, high-speed data transmissions—such as streaming video or internet services.
2. More B和width: Fiber optic cables are capable of carrying a wide range of frequencies in both directions simultaneously, 称为多路复用. This allows more data to be transmitted over the same wavelength, 提供更多的带宽功能.
3. Less Loss of Data: A single fiber optic cable is able to transmit signals with very minimal loss or attenuation, making them ideal for long-distance installations 和 large-scale service networks.
4. Immunity to Interference: As light passes through the glass fibers in a cable, there is little interference from external electrical fields or noise sources such as radar or EMI (electromagnetic interference). This makes them compatible with high-frequency transmissions such as satellite 通信系统 和 cell phone towers.
5. Improved Security: Fiber optic cables are also extremely secure because it is nearly impossible for anyone to intercept their signal without physically cutting into the cable itself – something that would be quickly noticed!
有两种基本类型的纤维， 单模和多模. 单模光纤芯径较小(8.3-10 microns) 和 holds advantages in terms of b和width 和 reach for longer distances, while multimode optical fibers have larger core diameters (50 microns or larger) 和 easily support most distances required in enterprise 和 data center networks, 成本通常低于单模安装.
如今，光纤技术在许多方面都有应用. 它用于传输语音和视频信号, 携带计算机数据, 也可以远距离发送信息.
Optical fibers are used to manufacture endoscopes which allow doctors to view inside the human body 和 perform surgery without the need for invasive scalpel procedures. Large core fibers can carry laser energy to facilitate the removal of tattoos, 清理历史遗迹, 以及激光制导防御系统的动力.
Distributed fiber optic 传感 (DFOS) allows for the entire length of an optical fiber to be used as a 传感 device. 燃料管道等结构, 桥梁, aircraft wings can have optical fibers embedded into them to detect such parameters as strain, temperature or sound 和 help ensure their structural integrity.
