Design and Analysis of Low -Loss Coupling between Fiber Array and Silicon Waveguides Based on Inclined End-face Coupling

This paper presents a low-loss and high-reliability optical coupling technique between silicon photodetector array chips and fiber arrays using end-face butt-coupling. The technique incorporates angled end-face coupling structures, anti-reflection coatings, high-precision fiber arrays, and active alignment to achieve efficient and reliable optical coupling. The angled end-face coupling structure is designed to suppress Fresnel reflections at the fiber/waveguide interface. The anti-reflection coating, deposited on the input end-face of the silicon photonic chip, further reduces end-face reflections. Analysis of additional coupling losses shows that when alignment errors are controlled within a specified range, the additional coupling losses meet the project requirements. The array coupling process includes chip end-face coating, fiber array design and fabrication, and the coupling of the silicon photodetector array chip with the fiber array. By optimizing process parameters and utilizing a bidirectional six-dimensional precision alignment stage, the coupling loss for all four channels is maintained below 1.3 dB. This work provides a robust solution for high-efficiency optical coupling in silicon photonics, with potential applications in optical communication, interconnects, and data centers.