Dispersion-allocated soliton technologies and the stretched-pulse mode-locked fiber laser

A new soliton transmission technology has been developed, which enables us to use already installed fiber cable. This is called the dispersion-allocated (D-A) soliton technique, by which a soliton can propagate even in fibers with normal GVDs as long as the average GVD is in the anomalous region. The idea of employing dispersion compensation for soliton transmission was first reported in 1992 with a view to minimizing the pulse broadening and expanding the amplifier spacing. When a D-A soliton is used, the sideband instability between the soliton and the dispersive waves has less influence because phase matching for the four-wave mixing is unlikely to occur. The soliton transmission technique described is very similar to stretched pulse mode-locking. In the stretched-pulse mode-locking technique, the fiber cavity consists of fibers with normal and anomalous GVDs. The existence of the normal GVD fiber means that the soliton cannot break into high-order solitons and, therefore, a stretched fiber laser can emit higher intensity pulses than ordinary soliton lasers. When the fiber dispersion is completely anomalous, solitons are likely to interact with the dispersive waves and are drastically altered when the intensity is increased. However, the D-A soliton has a larger power margin as it does not break into small pulses. The timing margin is also improved because the average GVD can be kept very small