Silicon-based optoelectronic filters based on a Bragg grating and P-i-N diode for DWDM optical networks

In this paper we propose an electrically controlled filter for the selection of channels in monitoring DWDM optical network. The highly selective filtering operation needed in this kind of communication systems is obtained with an all silicon device by combining the eletrical injection of free carriers in a forward biased P-i-N diode with a Bragg grating realized over the top of a Silicon on Insulator RIB waveguide. The combination of this fast electron device and the interference principle present under the periodic corrugation of the waveguide allows very fast reconfiguration of the filter. In order to increase filter performaces in terms of selectivity and crosstalk between adjacent channels, apodization of the duty-cycle of the grating is investigated; in this way the performances of the filter in terms of spectral bandwidth for 100 GHz and 50 GHz DWDM spacing become attractive and comparable to ITU specifications.