Ultrashort pulse generation and processing at 1.3 μm for ultra high speed photonic networks

At BT Laboratories we have been investigating some of the components which would be required for a 1.3 μm 100 Gbit/s network, of which the source itself is of key importance. We have identified gain-switched DFB lasers as prime candidates for the source, due to their simplicity. When gain-switched at a frequency of 1 GHz, these devices typically generate chirped pulses with a duration of around 20 ps. These chirped pulses can be compressed to ~ 5-6 ps by passing them through a normally dispersive element, often a length of fibre, although alternatively a chirped fibre grating can be used. We have shown that praseodymium doped fluoride fibres can be put to good use for the generation, transmission and processing of picosecond and subpicosecond pulses