Optical signal processing using linear system theory

Quadruple optical ring resonator (QORR) based filter architecture has been analyzed using delay line signal processing and Mason´s rule. Very wide free spectral range (FSR) of such filter is essential in commercial dense wavelength division multiplexing (DWDM). Vernier principle, one of the most effective methods of FSR expansion, has been used to get efficacious FSR of 856 THz. Silicon-on-insulator was used to fabricate such microring based optical resonators because of its high refractive index (Δ) contrast. These high index contrast materials are useful in minimizing bending loss. This also helps in higher integration density. A few important characteristics viz., group delay, dispersion and finesse of such filter have been discussed in this work.