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An ultra-small, low-power, all-optical flip-flop memory on a silicon chip


Ultra-small, low-power, all-optical switching and memory elements, such as all-optical flip-flops, as well as photonic integrated circuits of many such elements, are in great demand for all-optical signal buffering, switching and processing. Silicon-on-insulator is considered to be a promising platform to accommodate such photonic circuits in large-scale configurations. Through heterogeneous integration of InP membranes onto silicon-on-insulator, a single microdisk laser with a diameter of 7.5 µm, coupled to a silicon-on-insulator wire waveguide, is demonstrated here as an all-optical flip-flop working in a continuous-wave regime with an electrical power consumption of a few milliwatts, allowing switching in 60 ps with 1.8 fJ optical energy. The total power consumption and the device size are, to the best of our knowledge, the smallest reported to date at telecom wavelengths. This is also the only electrically pumped, all-optical flip-flop on silicon built upon complementary metal-oxide semiconductor technology.

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Figure 1: Structure of the microdisk laser and the lasing characteristics.
Figure 2: Experimental set-up.
Figure 3: Diagrams of the flip-flop operation and measured lasing power at a low switching speed.
Figure 4: High-speed measurement of the switching characteristics.


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This work was supported by the European FP7 ICT-projects HISTORIC, WADIMOS and PhotonFAB, the Belgian Fund for Scientific Research Flanders (FWO), and the IAP-project ‘Photonics@be’. The work of K.H. and T.S. is supported by the Institute for the Promotion of Innovation through Science and Technology (IWT) under a specialization grant. The authors thank M. Verbist for taking the cross-sectional image and acknowledge assistance from S. Verstuyft during device fabrication.

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G.M. conceived the idea and supervised the project. D.V.T. and R.B. provided assistance in the coordination of the project. L.L., R.K., T.S., G.R., E.G., T.d.V. and P.R. fabricated the devices. L.L., R.K. and K.H. performed the measurements. L.L. and G.M. wrote the manuscript.

Corresponding author

Correspondence to Geert Morthier.

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The authors declare no competing financial interests.

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Liu, L., Kumar, R., Huybrechts, K. et al. An ultra-small, low-power, all-optical flip-flop memory on a silicon chip. Nature Photon 4, 182–187 (2010).

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