Coupling properties of asymmetric high index contrast soft glass dual-core fiber in C-band

• Nondestructive coupling properties study of dual-core optical fiber was performed. • The nanometer level geometrical changes cause strong asymmetry effect in C-band. • Practical and numerical approaches brought similar coupling length spectral curves. In this study, we investigate the impact of asymmetry and excitation wavelength on the coupling properties of soft glass dual-core optical fibers. Recent technological advancements have led to the development of high index contrast two-component soft glass dual-core fibers with sufficient symmetry, creating a new platform for nonlinear all-optical switching tasks. However, the nonlinear propagation of femtosecond pulses, which has been experimentally demonstrated, is significantly influenced by the linear optical properties of the fibers, including spectral profiles of dispersion, coupling length, and coupling efficiency. Our contribution extends beyond the novel non-destructive experimental investigation of these properties. We also conduct extensive numerical studies on the linear transmission characteristics. The findings we obtained not only deepen the understanding of the nonlinear experimental results but also provide valuable insights for development of the next generation of dual-core fibers, which will be more suitable for all-optical data processing applications.