let’s know about fiber optics
Fiber optics is a type of transmission line or cable is made of glass or plastic is very smooth and smaller than a hair, and can be used to transmit light signals from one place to another. The light source used is usually a laser or LED. This cable is approximately 120 micrometers in diameter. Light that is in the optical fiber does not come out because the refractive index of glass is greater than the refractive index of air, because the laser has a very narrow spectrum. Speed optical fiber transmission is very high so it is great to use as a communication channel. The efficiency of the optical fiber is determined by the purity of the building blocks of glass / glass. The more pure glass material, the less light is absorbed by the fiber optics.
Structure of Fiber Optics
Broadly speaking, the structure of the optical fiber is divided into two parts, namely core and cladding (wrapping of the core). Caldiing have a function to protect the light that bounces off the core leads out to be reflected back into the core. Cladding can reflects the light from the core that leads out because the cladding have a lower refractive index.
In fact the optical fiber is also wrapped in a layer called resin-called jacket. This resin layer can absorb the light so as to prevent leakage that leads out of the core.
Types of Optical Fiber
Broadly speaking, the distribution of types of optical fibers can be seen from two aspects, namely based on the propagated mode and based on the core refractive index.
a. Based on the propagated mode optical fiber can be divided into two general categories:
• Single mode: single mode optical fiber that is have very small diameter (8-10 micrometers) which is almost equal to the wavelength of the emitted so that there is only one index that is not reflected beam to the wall cladding. Single mode have much greater bandwidth and can transmit data 50 times further than multimode. With the advantages of single mode does not mean that single mode not have disadvantage, because its diameter is small, the single beam mode with a spectral width requires little meaning requires a system with a more expensive cost.
Things that cause single mode over more reliable, stable, fast, and far-reaching is the core used is smaller than multi mode so disturbances in it due to distortion and overlapping light pulses is reduced.
• Multi mode: Technology is the technology of fiber multimode that have a core diameter greater than the single mode so that it can deliver more than one index-reflected light and bounce off the wall cladding to reach the end point. Multimode also has several advantages, namely by having a large diameter multimode can use the LED as a light source while a single-mode laser signal should be used as light sources. Besides the information signal on multimode move more freely and with a large core size is advantageous if the necessary connection between the core or it is called splicing.
Things that cause these technologies also brings inconvenience for users. When the number of modes is increased, the influence of dispersion effects of capital also increased. Capital dispersion (intermodal dispersion) is an effect where the light modes of a large number of recipients had reached the end of the time are out of sync with each other. This time difference will cause pulses of light to spread acceptance. The effect of this effect is achieved bandwidth can not be increased, so that communication becomes limited bandwidth.
b. Based on the core refractive index is divided into two:
• Step index: in step index optical fiber, the core have a homogeneous refractive index.
• Graded index: core refractive index approached closer to the smaller cladding. So the graded index, the central core has a refractive index value the most. Graded index fiber allows it to carry much more bandwidth, because the widening of the pulses that occur can minimized.