Optical fiber is a glass or plastic like wired structure used to transmit information in the form of optical signal from transmitter to receiver end. Whenever we talk about any communication system, we always look over losses. This paper is focused on dispersion loss and how to reduce it. When the pulses travel through optical fiber, after travelling some distance, each pulses start spreading and overlaps with each other and leads to dispersion loss. A phenomenon in which the optical signal gets spread into different colors, each color has its own wavelength and respectively each wavelength travels in different velocity, which cause time delay, and this leads to chromatic dispersion. This paper analyzed the optical fiber performance and reduced dispersion loss in fiber by taking various of FBG function and grating length into consideration. The performance of FBG examined in terms of bit error rate, quality factor value in eye height.