Research Initiation: Volume Holographic Optical Interconnection

光学互连元件可能会成为电气布线的一种强有力的替代方案，因为光子缺乏电子的相互作用性质。因此，光子互连提供了最小的信号恶化、对寄生(电容或电感)负载的免疫力以及对EMI的不敏感性等优点。当前的光学互连主要基于光纤、基于薄膜全息型的平面配置或基于可以执行矩阵-矢量或矩阵-矩阵乘法的光学空间光调制器。然而，使用薄全息图的方案的互连容量受到全息图面积的限制，而工作效率则受到薄膜厚度的窄相互作用区域的限制。另一方面，基于空间光调制器的光互连系统复杂、体积大。这项工作是最近提出的一种利用光折变晶体的三维光子互连的理论和实验研究。这些新颖的配置是基于体积(而不是平面)全息几何结构。它们的工作包括由大量全息光栅提供的复合布拉格反射机制；在体积内，由光学输入本身根据规定的互连图案产生栅格。

Optical interconnecting elements can potentially act as a powerful alternative to electrical wiring, because photons lack the interactive nature of electrons. As a result, photonic interconnections offer minimal signal deterioration, immunity to parasitic (capacitive or inductive) loading, and insensitivity to EMI, amongst other advantages. Current optical interconnects are based primarily on optical fibers, on planar configurations of the thin-film holographic type or on optical spatial light modulators which can perform matrix- vector or matrix-matrix multiplications. However, the interconnection capacity of schemes using thin holograms is restricted by the area of the hologram and the operating efficiency is limited by the narrow interaction region of the film thickness. On the other hand, optical interconnection systems based on spatial light modulators are complicated and bulky. The work projected here is a theoretical and experimental investigation of a recently proposed three-dimensional class of photonic interconnections utilizing photorefractive crystals. These novel configurations are based on volume (rather than planar) holographic geometries. Their operation involves a composite Bragg- reflection mechanism provided by a large multiplicity of holographic gratings; the gratings are generated inside the volume by the optical inputs themselves according to a prescribed interconnection pattern.