Bilinear Forms and Dark-Dark Solitons for the Coupled Cubic-Quintic Nonlinear SchrÕdinger Equations with Variable Coefficients in a Twin-Core Optical Fiber or Non-Kerr Medium*

Mei-Xia Chu,Bo Tian,Yu-Qiang Yuan,Ze Zhang,and He-Yuan Tian

Fig. 7 (Color online) Interaction between the two dark-dark soltions via Solutions (13), with $p_1=1,$ $p_2={3}/{4}+{1}/{2}i$, $c_1=0$, $c_2=-1$, $\mu_1=({13\sqrt{38}})/{76}$, $\mu_2=({3\sqrt{285}})/{38}$, $v=-1$, $R={1}/{2}$, $\xi_1^{(0)}=\xi_2^{(0)}=0$, and $b(z)=z$.