Achromatic Optics Enable Wavelength-Equalized Coupling in C-Band DWDM Satellite Laser Communication Terminals

With the increasing deployment of multi-wavelength free-space optical (FSO) systems in high-speed satellite data transmission, chromatic aberration has become one of the key factors limiting overall system performance. To address this challenge, this study proposes the integration of an achromatic metalens into a C-band FSO terminal. By employing a genetic algorithm (GA) for phase optimization, inter-wavelength phase compensation and focal consistency are achieved. The optimized metalens reduces the focal drift from 95 μm to 15 μm, representing an 84% reduction in focal deviation. System-level FSO link simulations further demonstrate that the achromatic design reduces the median equivalent BER from 1.2 × 10−2 to 3.5 × 10−3 (a 71% reduction) and increases the FEC-qualified ratio from 25% to 60% (a 35% improvement), confirming its effectiveness in improving multi-wavelength link reliability. These results verify the effectiveness of the proposed approach in enhancing transmission stability and fiber-coupling efficiency in DWDM-FSO systems, providing a promising optical design strategy for high-capacity and broadband space optical communication terminals.