Improved scattering performance of nonlinear directional coupler incorporating Kerr nonlinearity and Sellmeier dispersion designed at 1550 nm

Abstract The present work deals with a novel design of directional coupler analysed with Kerr nonlinearity and Sellmeier dispersion formula to include material dispersion and group velocity dispersion at 1,550 nm with a bandwidth of 20 nm. Coupled Mode Theory is employed to analyse power transfer between waveguides, while asymmetry is invoked through unequal propagation constants, resulting in phase mismatch and incomplete coupling. The present design is made asymmetric, it has been observed 105 % improvement of return loss, 42 % improvement of coupling factor and more than 300 % improvement of isolation compared to peer reviewed literature is reported, and it may be considered that the present design is made at higher THz compared to literatures reported at lower GHz spectrum only. Q-factor of the proposed design ranged from 685–1,585 compared with an earlier design’s range of 130–240, indicating that the proposed asymmetric DC has superior quality of resonance and optical confinement. Three-dimensional visualizations of modal evolution along the propagation direction and across wavelength provide insight into coupling dynamics, polarization dependence, and birefringence effects. An order of 10 6 improvement is reported for the magnitude of peak power in TE mode, favouring supremacy of the proposed modelling in the narrowband selection of interest.