Solitons in optical fibres and the soliton laser

In this paper, I describe both fundamental and higher-order solitons in optical fibres, their remarkable properties, and the first experimental observation of them. It will be shown that such solitons are easily created and, once formed, are quite stable in the one-dimensional world of single-mode fibres. Consequently, a number of exciting uses have already been found, or have been proposed for them. One of those uses is in the soliton laser, a mode-locked (short-pulse) laser, whose pulse characteristics are determ ined by a length of single-mode fibre in its feedback loop. Pulse width scales with the square root of the fibre’s length, in accord with N = 2 soliton behaviour. The first version of this device, based on a colour-centre laser broadly tunable in the 1.5 pm wavelength region, has already produced pulses as short as 0.13 ps. Compression in a second, external fibre has reduced those pulse widths to less than 50 fs, and reduction by at least another factor of two is considered likely in the near future.