Dispersion Estimation via Vestigial Sideband Filtering Using an Optical Delay Line Filter

Vestigial sideband filtering can be used for chromatic dispersion measurements. An optical delay line filter providing upper sideband (USB), lower sideband (LSB), and passband was designed for that application. The straightforward utilization is to measure the time delay between the USB and the LSB. A more practical approach is to estimate the chromatic dispersion (CD) by multiplying the USB and LSB signals in an electronic mixer and filtering out the DC component of the resulting signal. Due to the correlation between the USB and the LSB this signal is a measure for the delay between the sidebands induced by the CD. This approach was successfully demonstrated by experiments at a data rate of 10 Gbit/s. Furthermore, the properties of the optical filter influence (e.g., filter extinction) were assessed by numerical simulations.