Cross-section mismatch: metamaterials to the rescue

Coupling light into and/or out of a photonic integrated circuit is often accomplished by establishing vertical link between single-mode optical fiber and resonant waveguide grating, which then followed tapered waveguides. The operates as spot-size converter, laterally expanding or contracting the beam grating. In this work, we propose using subwavelength structures to achieve tapering functionalities. To end, designed metamaterial structure that enables modulation refractive index necessary either expand focus light. Furthermore, simulated through adequate numerical methods expanding, focusing performances were analyzed in terms efficiency mode profile matching. We achieved over 43 % 48 for integral overlap with transverse magnetic fundamental configurations, respectively, 49 51 power transferred.