Since the year 1990 till to the early of 21 century

the telecommunication demand for bandwidth has been increasing exponentially. Transmission technology is moving toward higher bit rates per wavelength and to dense wavelength division multiplexing （DWDM）.The specifications to determine polarization mode dispersion （PMD） coefficient with statistical methods are under consideration. The demand on high count fiber cable is increasing thereby increasing the applications for ribbon cable. The systems with alternating positive and negative dispersion TrueWave fibers need no dispersion compensation and provide better performance

which is the best choice for long distance terrestrial networks. The nonlinear effects can be reduced by increasing the fiber effective area .But present large effective area fibers （LEAF） still have some problems with higher zero dispersion slope and bending sensitivity

it is not ideal for terrestrial application and it is best for submarine cables. The optimum LEAF are still under development.