Optically powered smart pixels

Abstract

Recently, there is an increasing interest in smart pixel arrays for use in high density, high bandwidth interconnection networks.1,2 Optoelectronic integrated circuits (OEICs) are attractive components for such arrays. There are, however, critical limitations associated with 2-D chip architectures that prevent the OEIC-based design from achieving the expected high performance. One issue is the electrical voltage supply and pixel logic control lines which must be routed to each pixel. The nonzero impedance of these interconnects introduces crosstalk which ultimately limits the bandwidth of the system. In addition, the dc bias lines and their associated ac decoupling circuitry consume valuable chip area. We propose a novel interconnection architecture to confront the issues of crosstalk and layout, which utilizes the principle of optically powered smart pixels.3 Here, optical powering is locally provided to each pixel using an integrated photovoltaic cell. In this paper, we demonstrate an optically powered, integrated smart pixel. The InP based circuit can be dynamically tuned with an optical control beam to operate as an amplifier, bistable switch or as a latch/reset. The circuit has an optoelectronic gain of 2.5–11, and operates at 80 Mbit/s with an optical switching energy of only 3.8 pJ.