Asymmetric optical responses of photonic systems for forward and backward incidences are of great importance for practical applications. In this work, we theoretically demonstrate second-harmonic generation (SHG) with high contrast of harmonic generation efficiency for forward/backward pumping in non-chiral nanostructures. Hybrid metasurfaces consisting of dielectric nanodisks and their complementary plasmonic nanostructures exhibit strongly asymmetric and highly efficient SHG. Numerical results show that the SHG efficiency of 0.57 × 10⁻³% can be obtained for forward pumping with such a metasurface made of lithium niobate and gold. This value of SHG efficiency is 53 times higher than the case of backward pumping, revealing strongly asymmetric SHG.

对于向前和向后入射，光子系统的不对称光学响应对于实际应用非常重要。在这项工作中，我们从理论上论证了非谐波纳米结构中向前/向后泵浦的谐波产生效率具有高对比度的二次谐波产生（SHG）。由介电纳米盘及其互补的等离子体纳米结构组成的杂化超表面表现出强烈的不对称性和高效的SHG。数值结果表明，采用铌酸锂和金制成的金属表面进行正向泵送时，SHG效率为0.57×10 ^-3％。SHG效率的这个值是反向泵送情况下的53倍，这表明SHG非常不对称。