All-optical notch filters for ultra-wideband chaotic communications

In this paper, a wideband all-optical notch filter is proposed using two cascaded modified add-drop resonators from chalcogenide glass (ChG) and GaAsInP-InP waveguide materials. The system consists of ChG main ring and two small side rings called phase modulators made of the GaAsInP-InP materials. The plane waves are fed at the input and add ports, from which the chaotic signal outputs can be generated by the nonlinear effect induced into the center ring. The results have been simulated based on the scattering matrix method. Results have shown that the generated chaotic signals can be used for switching and secured communications. An ultra-fast switching time of ∼ 2 attoseconds is achieved. Moreover, the chaotic signals can be filtered by the stop band filters (notch filters). The free spectral range (FSR) of two cascaded ChGs is 1494.8nm. The output wavelength of the notch filters is tunable from 748.0-2242.2nm and 2242.8-3737.0nm. The band-stop of the notch filter is 1494.2nm. This approach will allow the implementation of the compact, and integrated notch filters in an on-chip scale circuit, which is useful for both light fidelity (LiFi) and wireless fidelity (WiFi) applications.