What is fiber optic
•Transferir como PPTX, PDF•
8 gostaram•4,285 visualizações
Optical fiber consists of an extremely pure fused silica core with a higher refractive index surrounded by a cladding layer of lower refractive index. This structure, along with the phenomenon of total internal reflection, allows light signals to be transmitted along the core. Optical fiber is produced by drawing fiber from a preform in a tall tower, resulting in an extremely thin, flexible glass strand well-suited for long-distance digital communication. Digital signals are transmitted through fiber using light modulated between on and off states, with common wavelengths being 850nm, 1310nm, and 1550nm, and transmission speeds ranging from 100Mbps to over 100Gbps. Fiber has significantly greater maximum transmission distances than copper at all data rates
Recomendados
Mais conteúdo relacionado
Mais procurados
Mais procurados (20)
Destaque
Destaque (17)
Semelhante a What is fiber optic
Semelhante a What is fiber optic (20)
Último
Último (20)
What is fiber optic
- 2. The Structure of Optical Fiber Extremely Pure Fused Silica – Very Low Loss for Long Distance Transmission Core – Higher Refractive Index Cladding – Lower Refractive Index Buffer Coating: Mechanical Protection
- 3. Snell’s Law and Total Internal Reflection Core Cladding Snell’s Law – Reflection and Refraction n = 1.5 n = 1.4
- 4. How is Glass Optical Fiber Made Glass Fiber Preform Fiber Drawing Process Fiber Drawing Tower (2 Stories Tall)
- 5. A Simple Fiber Optic Communication Link Laser Coupled Into Fiber Photodetector 1. Laser 2. Optical Fiber 3. Photodetector
- 6. Digital Communication via Optical Fiber Carrier Wave = Light Signal = On/Off Modulation Common Light Wavelength: (Infrared) 1. 850nm 2. 1310nm 3. 1550nm 4. more… Signal Speed: 1. 100 Mbps 2. 1000 Mbps 3. 2.5 Gbps 4. 10 Gbps 5. 40 Gbps 6. 100 Gbps
- 7. Fiber Has More Bandwidth Than Copper Max. Transmission Distance Copper Fiber 100 Mbit Ethernet 100 meters 40,000 meters 1 Gigbit Ethernet 100 meters 70,000 meters 10 Gigbit Ethernet 100 meters 80,000 meters
- 8. Get Even More Bandwidth with WDM WDM = Wavelength Division Multiplexer
- 9. More FREE Fiber Optic Tutorials FO4SALE.com Don’t Forget to Visit
Notas do Editor
- Hello everyone! This is Colin from Fiber Optics For Sale.In this video, I will explain what is fiber optics. So let’s get started.From its name, we know that fiber optics is composed of fiber and optics. Here fiber is a very thin plastic or glass strand. Optics means light. So fiber optics basically means light that travels in a strand of plastic or glass fiber.This picture shows a bunch of fiber enclosed in a single black color protective jacket.So how is light guided and travels inside the fiber? This video shows a beam of light that travels inside a water stream by total internal reflection. Optical fibers work the same way. So let’s take a look.
- The previous video gives us a basic idea of how light would travel inside a fiber. Now let’s see what a glass fiber is composed of.A glass fiber has a cylindrical structure and is composed of three layers. At the center is the core, core has higher refractive index. Outside of core is the cladding layer. Cladding layer has lower refractive index than the core.The third layer is a plastic buffer coating. This buffer coating doesn’t affect the fiber’s optical performance, it is there for mechanical protection only.The right picture shows how light is coupled into the fiber’s core and bounced back and forth in the core and travels along the fiber.The core and cladding layers are all based on fused silica which is a type of glass. But this fused silica is extremely clear, with almost no impurities. This transparency is extremely important, so that the light can travel for a very long distance, such as hundreds of kilometers with minimum loss. This makes trans-Pacific and trans-continent fiber optic communications possible.
- Here comes the question. Why doesn’t the light leak out of the fiber? That is why we have to explain the phenomenon of total internal reflection.The left picture shows Snell’s the law which guides how light travels at the interface of the core and cladding.The core has a higher refractive index n = 1.5. The cladding has a lower refractive index n = 1.4. When light incidents at the interface between the core and cladding at different angles, some power is reflected back, and some power enters into the cladding which is refracted. But when we increase the incident angle to greater than a critical angle theta c, no more light enters into the cladding, all light is reflected back into the core. This phenomenon is called Total Internal Reflection. Here total means 100% of the power is reflected back into the core.The important point here is the critical angle Theta c. If light enters the fiber less than Theta c, it will quickly leak out of the fiber and won’t travel long. When the light enters the core at an angle greater than Theta c, it will be bounced back and forth at the interface of core and cladding, and travels very long distance along the fiber with very low loss of power.This picture visually shows the total internal reflection process.
- The manufacturing of glass fibers go through two steps. In the first step a preform is made. This preform has exactly the same proportion of core and cladding as final fiber product, but in a much bigger size. It looks like a thick glass rod, as shown in the bottom picture.Then the preform is hanged at the top of a fiber drawing tower. The tower is a couple of stories tall as shown in the right picture.The preform is heated by a furnace which softens the glass. The softened glass drips and pulled downward by gravity. A diameter monitor carefully monitors the fiber’s diameter, which usually is 125um. Then the coater deposits a layer of plastic buffer coating for mechanical protection, which usually is 250um in diameter.And finally, the fiber is winded onto a spool for storage and transportation.
- A basic fiber optic communication system must have at least three components. The light source, which usually is a laser. The laser is turned on and off quickly by a driving circuit. In this modulation process, the original electronic signal is translated into light signal.The second part is the fiber. The fiber’s purpose is to transmit the light through a very long distance, such as from New York to Paris. And the third part is a photodetector. The photodetector detects the light and generates electronic current, in this process it translates the light signal back into electronic signal.Of course, real world systems are much more complicated, but this gives you a rough idea of how it works.
- This illustration shows the laser modulation process which turns the laser on and off by a electronic signal.The laser generates stable continuous light. The most common light colors, or wavelengths, are 850nm, 1310nm, 1550nm and more. The light itself is a electromagnetic wave and is called the carrier wave as shown here.The top is the electronic signal, which has much lower frequency than the carrier wave itself. When this signal is used to turn the laser on and off, the bottom illustration shows the generated pulse, which is low frequency signal envelop modulated on top of the high frequency carrier wave.The most common signal speeds include 100 Mbps, 1000 Mbps, 2.5 Gbps, 10 Gbps, 40 Gbps, and 100 Gbps. 100 Gbps is currently a state of art technology and many fiber optic companies are working hard to commercialize it.
- Many people searches on Google for the advantage of fiber over copper. Fiber’s most important advantage is its almost unlimited bandwidth.The bad thing with copper is that the higher speed the signal, the larger loss it gets. As shown in this picture, in coaxial copper cable, the higher speed the signal, the higher its loss. So high speed signal won’t travel long on a copper cable. After a just a short distance, maybe just a couple of hundred meters, the signal becomes too weak to work.On the other hand, the loss of signal has no dependence of its speed in optical fiber. So for the same speed, light signals travel much longer in fiber than electronic signals travel on copper cable.This table list the most common high speed Ethernet standards. For 100 Mbps, copper supports up to 100 meters, while fiber supports up to 40 kilometers. For Gigbit Ethernet, copper supports still 100 meters, fiber supports 70 kilometers. For 10 Gigbit Ethernet, copper is 100 meters, and fiber is 80 kilometers. Now you see the difference.The bottom picture shows the size comparison between a copper cable and an optical fiber, both carries the same bandwidth.
- There is trulyno match for fiber’s bandwidth capabilities. In order to fully utilize the fiber’s bandwidth, people are using WDM technologies to increases the bandwidth in tens of folds.WDM stands for Wavelength Division Multiplexer. What this means is that many different colors, or wavelengths, of light is put into a single fiber. This picture shows a simple 4 channel WDM, but there are 32 channels, 64 channels, or even more are available on the market now.Now imagine how many information can a single fiber carry. If each wavelength carries 40 Gbps signal, then a 10 channel WDM system can carry 400 Gbps. Not to mention a 100 channel WDM system.
- So there you have it. Please leave your comment below if you’d like to see other topics. Don’t forget to visit fo4sale.com for more free fiber optic tutorials. I will see you in the next video!