First integrated combiner based on self-switching in quantum dots
ABSTRACT We demonstrate all-optical switching in quantum dots (QDs). The switching is studied in an integrated optical combiner circuit. This is a Mach-Zehnder interferometer with an unequal power distribution over the branches. The refractive index is intensity dependent in the branches due to the QDs. Large all-optical nonlinearities are measured. This device is aimed to avoid an unwanted 3-dB loss, fundamental in passive optical splitters.
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ABSTRACT: Passive optical combiners have an unwanted 3-dB loss. This is avoided with optical switches, but these need control functions to synchronize with the optical signals. A nonlinear Mach-Zehnder interferometer can provide the combiner function without control signals. In the experiment reported here, this combiner was realized with a fiber component. Semiconductor optical amplifiers (SOAs) acted as the nonlinear phase shifting elements. Thus a proof-of-principle for the self-routing combiner is obtained: optical signals on either of the two input ports are guided to one and the same output port without any control mechanism in the interferometer. The nonlinear effect used is self-phase modulation, caused by carrier depletion in the SOAs as they approach saturation. The optical power at which the nonlinear switching occurred was about -2 dBm. The residual combiner loss was only 0.7 dB.IEEE Photonics Technology Letters 12/2001; · 2.18 Impact Factor
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ABSTRACT: We report on an effective way to continuously tune the emission wavelength of InAs quantum dots (QDs) grown on InP (100) by chemical-beam epitaxy. The InAs QD layer is embedded in a GaInAsP layer lattice matched to InP. With an ultrathin GaAs layer inserted between the InAs QD layer and the GaInAsP buffer, the peak wavelength from the InAs QDs can be continuously tuned from above 1.6 μm down to 1.5 μm at room temperature. The major role of the thin GaAs layer is to greatly suppress the As/P exchange during the deposition of InAs and subsequent growth interruption under arsenic flux, as well as to consume the segregated surface In layer floating on the GaInAsP buffer layer. © 2004 American Institute of Physics.Applied Physics Letters 01/2004; 84(2):275-277. · 3.52 Impact Factor