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

我们发现，在非对称晶胞的金属光子晶片中，即使在垂直入射的情况下，也存在光生电压。这种光电压与波长有关，可以用金属中入射、反射、衍射光和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好地解释了实验光谱。我们还测量了具有正方形孔阵的Au/Almina/Au三层结构的光生电压，在一定的波长范围内呈现负折射率。实验发现，在负折射率区，模具有负的群速度。本研究项目中最重要的发现是圆偏振光在40 nm厚的方形圆孔阵列薄膜上产生的横向光电压。当电路…的感测改变时，电压改变其符号更多的Ar偏振。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霍尔效应，这是由于圆偏振引起的圆周运动产生的直流磁场所致。从这个角度出发，我们对反射光和透射光进行了偏振分析，以估算光传递给电子的角动量。当圆偏振光斜入射到样品上时，反射光和透射光变为椭球偏振光--从椭圆度和方位角，我们估计了传递给电子的角动量。由于衍射光携带的角动量很弱，所以被忽略了。在这个项目中，我们将注意力集中在金属光子晶片中诱导的光生电动形式上，发现平移动量和角动量是导致这一现象的原因，因此我们开辟了一个将光物理和输运现象联系起来的新的研究领域。较少

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