Kroo N, Farkas Gy, Dombi P, Varró S
Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, 1121 Budapest, Konkoly-Thege M. út 29-33, Hungary.
Opt Express. 2008 Dec 22;16(26):21656-61. doi: 10.1364/oe.16.021656.
Evanescent fields of surface plasmon polaritons (SPP) above metal surfaces can reach 1-2 orders of magnitude higher, nearly atomic field strengths in comparison to the relatively weak exciting laser fields of a femtosecond Ti:sapphire laser oscillator. We used these high plasmonic fields to study the characteristic SPP phenomena of intense field optics experimentally. It was found that both the intensity and the angular distribution of SPP emitted light depend nonlinearly on the exciting laser intensity in the higher-intensity, non-perturbative range of the interactions. These results are supported by our theory. At these strong excitations, an additional, depolarized, diffuse spectrum also appeared which can be attributed either to the fluorescence of Au, or to the non-equlibrium Planck radiation, originating from the fast cooling of the conduction electron cloud of Au excited by the femtosecond laser pulse.
与飞秒钛宝石激光振荡器相对较弱的激发激光场相比，金属表面上方表面等离激元极化激元（SPP）的倏逝场强度可高出1 - 2个数量级，接近原子场强。我们利用这些高等离子体场通过实验研究强场光学的特征SPP现象。研究发现，在相互作用的高强度、非微扰范围内，SPP发射光的强度和角分布均非线性地依赖于激发激光强度。这些结果得到了我们理论的支持。在这些强激发条件下，还出现了一个额外的、去极化的漫射光谱，这要么归因于金的荧光，要么归因于非平衡普朗克辐射，后者源于飞秒激光脉冲激发的金传导电子云的快速冷却。
