Anderson D Z, Lininger D M
Appl Opt. 1987 Dec 1;26(23):5031-8. doi: 10.1364/AO.26.005031.
We view a real-time volume holographic medium as a programmable two-port device that operates on an optical electric field. A photorefractive two-port operator can be used to establish the interconnects required by neural network models. The index grating that forms in the medium serves to fully interconnect two layers of processing units and at the same time sums the input signals to the output layer. The dynamics of grating formation in photorefractive media are used to indicate the time evolution of the two-port operator when the diffraction efficiency of the medium is small. We experimentally demonstrate a projection operator whereby we store and recall, in iron-doped lithium niobate, seven 1-D images. The image storage is done without the usual angle or spatial encoding of reference beams. A projection operator is used to recognize what features of an input belong to a space defined by a set of stored vectors. The two-port operator can also be used to perform the complementary function: to recognize what features of an input do not belong to this space.
我们将实时体全息介质视为一种基于光电场运行的可编程双端口设备。光折变双端口算子可用于建立神经网络模型所需的互连。介质中形成的折射率光栅用于完全互连两层处理单元，同时将输入信号求和至输出层。当介质的衍射效率较小时，光折变介质中光栅形成的动力学用于指示双端口算子的时间演化。我们通过实验演示了一种投影算子，借此在掺铁铌酸锂中存储和再现七幅一维图像。图像存储无需参考光束的常规角度或空间编码。投影算子用于识别输入的哪些特征属于由一组存储向量定义的空间。双端口算子还可用于执行互补功能：识别输入的哪些特征不属于该空间。
