GaAs/AlAs Multilayer Cavity with InAs Quantum Dots Embedded in Strain-Relaxed Barriers for Planar-Type Optical Kerr Gate Switches

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A GaAs/AlAs multilayer cavity containing self-assembled InAs quantum dots (QDs) embedded in strain-relaxed In0.35Ga0.65As barriers has been studied for planar-type optical Kerr gate switches. The multilayer cavity structure with smooth GaAs/AlAs interfaces was successfully grown on a (001) GaAs substrate by molecular beam epitaxy despite the lattice strain relaxation induced in the half-wavelength ($\lambda/2$) cavity layer. Time-resolved optical measurements at the cavity mode ($\lambda = 1.46$ μm) were performed by a pump–probe method at room temperature. Although only two layers of the InAs QDs were inserted into the $\lambda/2$ cavity layer, a large transmission change caused by the absorption saturation in the resonant QDs was clearly observed. The temporal profile was dominated by a fast (${\sim}16$ ps) decay component, which comes from carrier relaxation into the nonradiative centers arising from the lattice strain relaxation. We have also shown that an ultrafast response time (${<}1$ ps) of the strongly enhanced optical Kerr signal is determined by the photon lifetime in the multilayer cavity.
2010-04-25