Investigation on photo-induced voltage phenomena in metallic photonic crystal slabs

我们发现，在具有非对称晶胞的金属光子晶体板中，即使正常入射也存在光致电压。这种光电压依赖于波长，可以用入射光、反射透射光、衍射光和金属中的电子之间的平移动量守恒来解释。事实上，基于散射矩阵形式的数值计算很容易解释实验光谱。我们还测量了具有方形孔阵列的Au/almina/Au三层结构在一定波长范围内呈现负折射率的光致电压。实验发现，在负折射率区域，模态具有负群速度。本研究项目最重要的发现是圆偏振光在40nm厚的圆孔方阵的An薄膜上产生的横向光电压。电压的符号随着圆周的变化而变化。我们通过数值计算证实了这一效果。这种由圆偏振光引起的横向光电压可以解释为一种由圆偏振光引起的圆周运动所产生的直流磁场所引起的霍尔效应。从这个角度出发，我们对反射光和透射光进行偏振分析，以估计光传递给电子的角动量。当圆偏振光斜入射到样品上时，反射光和透射光变成椭球偏振，从椭圆度和方位角估计了传递给电子的角动量。衍射光束携带的角动量被忽略，因为它们很弱。本课题重点研究了金属光子晶体板中产生的光致电动势形式，发现平动动量和角动量是导致这一现象的原因，从而开辟了光物理与输运现象联系起来的一个新的研究领域。少

We have found that photo-induced voltage was found to exist even for the normal incidence in metallic photons crystall slabs with asymmetric unit cell. This photo-voltage is dependent on wavelength It is found to be explained in terms of conservation of translational momentum among incident, reflection transmission, diffraction lights and electrons in metal. In fact, numerical calculation based on scattering matrix formalism readily explains the experimental spectra. We also measured photo-induced voltage for Au/almina/Au tri-layer structure with square array of holes, which exhibits negative index of refraction at certain wavelength range. It was experimentally found that at the negative index region, the mode has negative group velocity. The most important discovery in this research project is the transverse photo-voltage induced by circularly polarized light on 40nm-thick An film with square array of circular holes. The voltage changes its sign upon the change in sense of the circul … More ar polarization. We confirmed the effect by carrying out a numerical calculation. This transverse photo-voltage induced by circularly polarized light can be interpreted as a kind of Hall effect due to the DC magnetic field generated by the circular motion induced by circular polarization. From this point of view, we made polarization analysis of reflection and transmission light in order to estimate the angular momentum transferred from the light to the electrons. When circular polarized light is incident on the sample obliquely the reflection and transmission light becomes of ellipsoidal polarization- From ellipticity and azimth angle, we estimated angular momentum transferred to the electron. Angular momentum carried by diffracted beams were ignored because they are weak. In this project, we focused our attention to the photo-induced electromotive form induced in metallic photons crystal slabs and found that translational as well as angular momenta are responsible to the phenomena Thus we have opened up a new research field connecting photophysics and transport Phenomena. Less