Surface metallization in Z-cut Cu-doped lithium niobate and its isomorphous lithium tantalate slabs was achieved by exhibiting metal optical properties in the visible regime using ab initio calculation. The giant opposite surface potentials were measured with sKPFM, indicating large amount of surface charges accumulated. The metallization was firstly evidenced from reflectivity enhancement under single laser beam irradiation on a Cu-doped LT slab, which is compared with the calculated reflectivity from a metallic film, seemingly amplified by energy coupling from visible surface plasmon polaritons supported by the metallic film. Since the very first reflection (VFR) is dictated by what happens in the subwavelength range, it leads us a direct way to monitoring SPPs excitation in the metallic layer. The VFR varies from 17% to 86% under two counterpropagating beams illumination, pointing clearly to a subwavelength energy coupling via SPPs. In addition, several intriguing phenomena were observed and aligned well with the SPPs picture. This work should be universal to all n-type ferroelectric oxides with photorefractive and photovoltaic effects, unveiling a missing important aspect in the past and opening an avenue towards designing novel photonic circuits, devices and active plasmonics applications in a truly nanometric scale.

Z-切铜掺杂铌酸锂及其同形钽酸锂平板中的表面金属化是通过使用从头算的方法在可见光区表现出金属光学性能来实现的。用sKPFM测量了巨大的相反表面电势，表明积累了大量表面电荷。首先通过掺杂铜的LT平板在单激光束照射下的反射率增强证明了金属化，并将其与金属膜的计算反射率进行了比较，表面反射率似乎是由金属膜支撑的可见表面等离激元极化子的能量耦合所放大。由于第一次反射（VFR）是由在亚波长范围内发生的事情所决定的，因此它为我们提供了一种直接的方法来监控金属层中SPP的激发。在两个反向传播的光束照射下，VFR在17％到86％之间变化，这清楚地表明了通过SPP进行的亚波长能量耦合。此外，还观察到了一些有趣的现象，这些现象与SPP图像吻合得很好。这项工作对于具有光折射和光伏效应的所有n型铁电氧化物应该是普遍的，揭露了过去缺失的重要方面，并为在真正的纳米级设计新颖的光子电路，器件和有源等离子应用打开了道路。