Compact tunable FIR dispersion compensator in SiON technology

We present a tunable dispersion compensator, based on a sixth-order finite impulse response lattice filter. The filter has a free spectral range of 100 GHz and can be tuned for linear group delay slopes between -100 and 100 ps/nm with less than 1-ps ripple over a usable bandwidth of more than 60 GHz. Within this usable bandwidth, the average polarization-mode dispersion is low, reaching 2.4 ps only for extreme group delay slopes. The filter can also generate higher order group delay curves, for example for dispersion slope compensation.