Optical transistors capable of forming an interconnected network are fundamental for optical information processing but have not been realized on a silicon chip. To be practical, an optical transistor must be cascadable, provide signal gain with logic level restoration, have input/output isolation and be free from critical biasing. It also needs to be compact and compatible with complementary metal-oxide-semiconductor (CMOS) technology. However, almost all previous proposals or demonstrations of optical transistors fail to meet these criteria.;In this work, we demonstrate an all-silicon optical transistor using enhanced optical nonlinearity in two 5-micrometer-radius silicon rings which allows a small optical signal to control a large signal. While a single device can simultaneously achieve >3 dB signal gain and >20 dB ON/OFF ratio, a cascaded device, can yield a signal gain of >7 dB. An output ON/OFF ratio over 18 dB can be achieved with an input ON/OFF ratio of merely 2 dB. It also accomplishes fundamental logic operations like NAND or NOR on a single device, which normally require multiple electronic transistors. The optical transistor demonstrated here has many characteristics of its electronic analogue and promises to be a stepping stone for future optical computing.;This work will also touch base on some of the early work on realizing inverse opal photonic crystals as an efficient thin film solar cell back-reflector and on fabricating photonic crystals through a scaffold of hydrogen silsesquioxane resist.
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