100 Gbit/s dispersion compensation using cascaded chirped fibre grating transmission filters

The authors report the application to dispersion correction of a simple yet novel low insertion loss, polarisation independent, all-fibre transmission filter incorporating chirped Bragg reflectors. Implementing this filter, they overcome the problem of high insertion loss associated with grating application, i.e. chirped gratings operate in reflection, so in order to recover the reflected radiation they are used in conjunction with a 50:50 coupler, incurring a signal loss of at least 6 dB. The dispersion correction has been demonstrated at 112 Gbit/s (470 fs pulses) and pulse width recovery with a figure of merit as high as 0.9 has been achieved in propagating over 3.9 km of dispersion shifted fibre or 260 m of standard telecommunications fibre. The authors have also demonstrated that it is possible to cascade the chirped grating transmission filters with little degradation in the figure of merit for pulse recovery.