Abstract: Directional couplers (DCs) are the basic elements for constructing various silicon photonic devices, including Mach– Zehnder switches (MZSs). Here, we propose a novel 2×2 bent directional couplers based on Bézier curves designed with an efficient semi-inverse design method. However, it is challenging due to the coupling between fibers and waveguides, which is highly sensitive. The design and fabrication of a compact, low-loss, broadband directional coupler (DC) based duplexer operating in the near-infrared (NIR) region are demonstrated. The duplexer exhibits high selectivity and coupling eficiency (CE), for target wavelengths of 1530 nm and 1653. Based on Finite Difference Eigenmode, Finite-Difference Time-Domain simulations, and experimental measurements. A directional coupler serves as an essential passive component in integrated photonic systems, allowing precise splitting or combining of optical signals between two closely. Directional couplers are essential components in integrated photonics.
