Efficient silicon-photonics edge coupler with double isolation layers

Although edge couplers with suspended structures demonstrate excellent optical coupling performance, they are prone to damage in practical applications. This paper proposes an efficient edge coupler with a double isolation layer structure, designed for efficient coupling with standard single-mode fibers. The proposed coupler employs a double isolation layer composed of SiO2 and refractive index-tunable SiO_xN_y to replace the air cladding in suspended couplers. This design significantly enhances the device's reliability and effectively improves coupling performance. Simulation results indicate that the coupler not only exhibits low coupling loss but also possesses extremely low polarization-dependent loss.