Switching dynamics in adiabatically coupled PT-symmetric directional coupler consisting of three nonlinear waveguides

We design and numerically investigate the switching dynamics between two outer waveguides in parity-time (PT)-symmetric adiabatically coupled three waveguides nonlinear directional coupler (NLDC) system. The study is performed for different combinations of linear and nonlinear waveguides using coupled mode theor y (CMT). Here, one of the outer waveguides has variable gain and the other has equal amount of variable loss while the middle waveguide is neutral. The merits of different configurations of PT-symmetric NLDC over the conventional NLDC are also discussed in detail. In particular, it has been noticed that the device provides switching even in case when middle waveguide is nonlinear, and the outer waveguides are linear for which conventional system behaves as linear coupler. In addition, we study the effect of loss to gain ratio on critical switchin g power. Further, the effects of launched light power and gain (loss) value on the transmitted power are investigated.

Automated summary

We design and numerically investigate the switching dynamics between two outer waveguides in a parity-time (PT)-symmetric adiabatically coupled three waveguides nonlinear directional coupler (NLDC) system. The study shows that the device can provide switching even when the middle waveguide is nonlinear and the outer waveguides are linear. Furthermore, the effect of loss to gain ratio on critical switching power and the impact of launched light power and gain (loss) value on transmitted power are also studied.