Yoon Jae Woong, Park Woo Jae, Lee Kyu Jin, Song Seok Ho, Magnusson Robert
Department of Physics, Hanyang University, Seoul 133-791, South Korea.
Opt Express. 2011 Oct 10;19(21):20673-80. doi: 10.1364/OE.19.020673.
We report surface-plasmon mediated total absorption of light into a silicon substrate. For an Au grating on Si, we experimentally show that a surface-plasmon polariton (SPP) excited on the air/Au interface leads to total absorption with a rate nearly 10 times larger than the ohmic damping rate of collectively oscillating free electrons in the Au film. Rigorous numerical simulations show that the SPP resonantly enhances forward diffraction of light to multiple orders of lossy waves in the Si substrate with reflection and ohmic absorption in the Au film being negligible. The measured reflection and phase spectra reveal a quantitative relation between the peak absorbance and the associated reflection phase change, implying a resonant interference contribution to this effect. An analytic model of a dissipative quasi-bound resonator provides a general formula for the resonant absorbance-phase relation in excellent agreement with the experimental results.
我们报道了表面等离子体介导的光在硅衬底中的全吸收。对于硅上的金光栅，我们通过实验表明，在空气/金界面激发的表面等离子体激元（SPP）导致全吸收，其速率比金膜中集体振荡的自由电子的欧姆阻尼速率大近10倍。严格的数值模拟表明，SPP共振增强了光在硅衬底中向多个损耗波阶次的前向衍射，而金膜中的反射和欧姆吸收可忽略不计。测量的反射和相位光谱揭示了峰值吸光度与相关反射相位变化之间的定量关系，这意味着共振干涉对该效应有贡献。一个耗散准束缚谐振器的解析模型提供了一个共振吸光度-相位关系的通用公式，与实验结果非常吻合。
