Dispersion managed optical transmission lines and fibers

There has been a rapid advance in wavelength-division multiplexing (WDM) an d high bit-rate time-division multiplexing (TDM) as techniques for coping w ith burgeoning demand for transmission capacity. In the past this expansion of capacity has been achieved by 2.5-Gbit/s and 10-Gbit/s WDM using the C- band (around 1550 nm), but research on the 1600-nm L-band (around 1600 nm) is being stepped up to obtain further expansion. With the achievement of 40 -Gbit/s speeds, which mark the limit of electrical signal processing, optic al TDM, with speeds of 100 Gbit/s, is coming into use. In this kind of high -density, high bit-rate WDM transmission, the occurrence of nonlinear pheno mena within optical fibers reduces transmission quality, and this raises th e importance of technology for suppressing non-linearity and specifically, in the case of WDM transmission systems, of four-wave mixing (FWM). Obvious ly there is also the problem of signal distortion due to dispersion, so tha t technology for suppressing cumulative dispersion is also essential. There is also a need for transmission lines with sophisticated dispersion manage ment over a wide band of wavelengths, and it may be consisted of novel fibe rs.