Lin Shiyun, Ishikawa Yasuhiko, Wada Kazumi
Department of Materials Engineering, The University of Tokyo, Tokyo, Japan.
Opt Express. 2012 Jan 16;20(2):1378-84. doi: 10.1364/OE.20.001378.
Optical circuits are low power consumption and fast speed alternatives for the current information processing based on transistor circuits. However, because of no transistor function available in optics, the architecture for optical computing should be chosen that optics prefers. One of which is Binary Decision Diagram (BDD), where signal is processed by sending an optical signal from the root through a serial of switching nodes to the leaf (terminal). Speed of optical computing is limited by either transmission time of optical signals from the root to the leaf or switching time of a node. We have designed and experimentally demonstrated 1-bit and 2-bit adders based on the BDD architecture. The switching nodes are silicon ring resonators with a modulation depth of 10 dB and the states are changed by the plasma dispersion effect. The quality, Q of the rings designed is 1500, which allows fast transmission of signal, e.g., 1.3 ps calculated by a photon escaping time. A total processing time is thus analyzed to be ~9 ps for a 2-bit adder and would scales linearly with the number of bit. It is two orders of magnitude faster than the conventional CMOS circuitry, ~ns scale of delay. The presented results show the potential of fast speed optical computing circuits.
与当前基于晶体管电路的信息处理方式相比，光学电路具有低功耗和高速的特点。然而，由于光学领域不存在晶体管功能，因此应选择光学领域所青睐的光学计算架构。其中之一是二叉决策图（BDD），在该架构中，信号通过从根节点发送光信号，经过一系列开关节点到达叶节点（终端）来进行处理。光学计算的速度受限于光信号从根节点到叶节点的传输时间或节点的切换时间。我们基于BDD架构设计并通过实验演示了1位和2位加法器。开关节点是调制深度为10 dB的硅环形谐振器，其状态通过等离子体色散效应改变。所设计环形谐振器的品质因数Q为1500，这使得信号能够快速传输，例如，通过光子逃逸时间计算得出的传输时间为1.3 ps。因此，对于一个2位加法器，总的处理时间经分析约为9 ps，并且会随位数呈线性增加。这比传统的CMOS电路快两个数量级，传统CMOS电路的延迟在纳秒级别。所展示的结果表明了高速光学计算电路的潜力。
