Grant R M
The Reactor Institute, Delft.
Appl Opt. 1966 Feb 1;5(2):333-41. doi: 10.1364/AO.5.000333.
It has been demonstrated that it is possible to control the intensity of visible and infrared light being transmitted through cadmium sulfide by controlled variations in photoelectrically induced free charge carrier densities which absorb the transmitted light. The free carrier optical absorption coefficient is extended to fit the case of photoelectrically induced free carrier absorption in semiconductors. This results in a theoretical modulation parameter which predicts the extent to which light transmission can be controlled by induced free carrier absorption. An experimental technique is presented which demonstrates that photoelectrically induced variations in the density of free carriers in CdS can indeed bring about a consequential control of the light transmission. Complete control over the transmission, in addition to light amplification by stimulated absorption, is demonstrated in CdS for both infrared and visible light between 0.6 micro and 4.0 micro. Theoretically computed and experimentally observed values of modulation are in fair agreement, considering the limitation of the theory and the nature of the solid. The observed transmitted wavelength dependence in CdS is discussed on the basis of both the free carrier absorption theory and various photoconductivity mechanisms, and it is shown to be reasonably consistent with modern theory.
已经证明，通过光致电感应自由电荷载流子密度的可控变化来吸收透射光，可以控制透过硫化镉的可见光和红外光的强度。自由载流子光吸收系数经过扩展，以适用于半导体中光致电感应自由载流子吸收的情况。这产生了一个理论调制参数，该参数可预测光透射可通过感应自由载流子吸收进行控制的程度。本文提出了一种实验技术，该技术表明，硫化镉中自由载流子密度的光致电感应变化确实可以对光透射进行相应的控制。在硫化镉中，对于0.6微米至4.0微米之间的红外光和可见光，除了通过受激吸收实现光放大外，还展示了对透射的完全控制。考虑到理论的局限性和固体的性质，理论计算值和实验观测到的调制值相当吻合。基于自由载流子吸收理论和各种光电导机制，讨论了在硫化镉中观察到的透射波长依赖性，结果表明它与现代理论合理一致。
