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

我们发现，即使光子垂直入射到具有非对称晶胞的金属晶体中，也存在光生电压。这种光电压与波长有关，可以用入射光、反射光、透射光、衍射光和金属中电子之间的平动动量守恒来解释。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Au/Almina/Au三层结构的光生电压，该结构在一定波长范围内呈现负折射率。实验发现，在负折射率区，该模式具有负群速度。本研究项目中最重要的发现是圆偏振光在40 nm厚的正方形圆孔阵列的Au膜上产生的横向光电压。电压随电路方向的变化而改变其符号。 关于我们 ar极化。我们通过数值计算证实了这种效应。这种由圆偏振光引起的横向光电压可以解释为一种霍尔效应，这是由于圆偏振引起的圆运动产生的直流磁场引起的。从这个角度出发，我们对反射光和透射光进行了偏振分析，以估计从光到电子的角动量。当圆偏振光斜入射到样品上时，反射光和透射光都变成椭球偏振，从椭圆度和方位角出发，估算了传递给电子的角动量，衍射光束携带的角动量很弱，可以忽略不计。在本项目中，我们将注意力集中在金属光子晶体板中产生的光生电动势形式上，并发现这种现象不仅与角动量有关，而且与平移动量有关，从而开辟了一个将物理学与输运现象联系起来的新的研究领域。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