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A fast low-power optical memory based on coupled micro-ring lasers


The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information1. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data2. Recently, ring lasers with extremely small size and low operating power have been made3,4,5,6,7, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40 µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20 ps with 5.5 fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

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Figure 1: Two micro-ring lasers coupled via a waveguide.
Figure 2: A memory element formed by two 16 µm diameter micro-ring lasers coupled via a waveguide on a InP/InGaAsP photonic integrated circuit.
Figure 3: Oscilloscope traces showing the switching of the memory element between states.

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This work was supported by the Netherlands Organization for Scientific Research (NWO) through the ‘NRC photonics’ grant.

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Correspondence to Martin T. Hill.

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Hill, M., Dorren, H., de Vries, T. et al. A fast low-power optical memory based on coupled micro-ring lasers. Nature 432, 206–209 (2004).

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