2012 Volume 40 Issue 5 Pages 375-
We demonstrate photo-detection at 1.55-μm wavelength light using a photonic crystal nanocavity with an integrated p-i-n junction. The device is made from silicon and integrated on a chip. Our results showed that it has an extremely low dark current of 15 pA and can operate at high sensitivity. The detectable smallest input light was 0.9 nW, which outperformed other detectors such as a germanium detector on silicon due to the strong confi nement of the light by ultrahigh-Q photonic crystal nanocavity. We also performed detailed theoretical and numerical analysis and showed that quantum effi ciency of 12.5% is possible using two-photon absorption. Higher effi ciency is possible if we can increase the onephoton absorption or the cavity’s Q. Based on our analysis, the sensitivity can be reduced to 1.8 pW due to the low dark current.