Analysis of Fiber bragg grating as dispersion compensator

Fibre optic communication a method of transmitting vital information from one point to another by sending pulses of light through an optical fiber. This light wave acts as an electromagnetic carrier wave which is modulated to carry information. Fiber optic cables are gaining popularity due to their fast transmission rates and the ease of use. Fibre optic cables are being used in place of electronic transmission. the various steps involved in the process of communication using fibre optic cables are as follows. creating an optical signal using a transmitter, relaying the signal along the wire, recieving the generated signal and converting it into an electrical signal. On the technology demand the transmition of information over large distances at appreciable speed is required. The fbg perform the task of transmission of the information with the speed with the requirement of the system .In today scenario we can see the network of FBG cable is being increased for digitalization of system. But as we know each system has some limitation, so optical fiber is running on the limitation of installation cost and the very important i.e. “Dispersion”. 

Because this is the property of signal pulse that it get broaden as it traveled into the fiber for some distance .so in order to improve the bit rate of the system one can improve the pulse entered in the optical fiber but it may possible that it ger broaden after some time travel into the fiber .Because these pulse get overlap o each other and create ISI so the noise come into the network and dispersion may present in system. We can also understand these term in the way like the phase velocity and group velocity of optical fiber is depend on frequency it is called “Dispersion”. The generation of optical pulse should be in such manner that can generate pure pulse with proper spacing and according the requirement of application. This is the first step to generate optical system by converting electrical signal into optical one. These optical information signals get modulated with optical source signal and make two types of pulse RZ and NRZ. In the RZ format, each optical pulse representing bit 1 is shorter than the bit slot, and its amplitude returns to zero before the bit duration is over. In the NRZ format, the optical pulse remains on throughout the bit slot and its amplitude does not drop to zero between two or more successive 1 bits. As a bit pattern, pulse width varies whereas it remains the same in the case of RZ format. In optical communication the use of RZ format help the design of high-capacity light wave systems. The optical carrier frequencies are 200 THz, whereas the microwave carrier frequencies are 1 GHz. It increases the information capacity of optical communication systems by a factor of up to 10,000, because of high carrier frequencies used for light wave systems.