Hi
Amongst the various techniques proposed in the literature, the ones that appear to hold immediate promise for dispersion compensation and management could be broadly classified as: dispersion compensating fibers (DCF), chirped fiber bragg gratings (FBG) and high-order mode (HOM) fiber. The idea of using dispersion compensation fiber for dispersion compensation was proposed in 1980 but, until after the invention of optical amplifiers, DCF began to be widespread attention and study. As the products of DCF are more mature, stable, not easily affected by temperature, wide bandwidth, DCF has become a most suitable method of dispersion compensation. There is positive second-order and third-order dispersion value in SMF, while the DCF dispersion value is negative. So by inserting a DCF, the average dispersion is close to zero.
The use of dispersion compensating fibers is an efficient way to upgrade installed links of standard single mode fiber (SMF). Conventional dispersion compensating fibers have a high negative dispersion -70 to -90 ps/nm.km and can be used to compensate the positive dispersion of
transmission fiber in C-band. According to the relative position of DCF and single mode fiber, post-compensation, pre-compensation and
symmetrical/mix compensation, is proposed. DCF precompensation scheme achieve dispersion compensation by placing the DCF before a conventional single mode fiber or after the optical transmitter. Post-compensation scheme achieve dispersion compensation by placing the DCF after the single mode fiber. Symmetrical/mix compensation scheme is consist .