All-optical switching due to state-filling in quantum dots
  We report all-optical switching due to state-filling in quantum dots (QDs) within a Mach-Zehnder Interferometric (MZI) switch. The MZI was fabricated using InGaAsP/InP waveguides containing a single layer of InAs/InP QDs. A 1530-1570 nm probe beam is switched by optical excitation of one MZI-arm from the top. By exciting below the InGaAsP bandgap, we prove that the refractive index nonlinearity is only due to the QDs. The switching efficiency is 2 rad/(microW absorbed power). Probe wavelength insensitivity was obtained using a broad distribution of QDs. 
R. Prasanth, J.E.M. Haverkort, A. Deepthy, E.W. Bogaart, J.J.G.M. van   der Tol, E.A. Patent, G. Zhao, Q. Gong, P.J. van Vel...