Detailed Design and Characterization of All-Optical Switches Based on InAs/GaAs Quantum Dots in a Vertical Cavity

We propose an all-optical switch based on selfassembled InAs/GaAs quantum dots (QDs) within a vertical cavity. Two essential aspects of this novel device have been investigated, which includes the QD/cavity nonlinearity with appropriately designed mirrors and the intersubband carrier dynamics inside QDs. Vertical-reflection-type switches have been fabricated with an asymmetric cavity that consists of 12 periods of GaAs/Al_0.8Ga_0.2As for the front mirror and 25 periods for the back mirror. All-optical switching via the QD excited states has been achieved with a time constant down to 23 ps, wavelength tunability over 30 nm, and ultralow power consumption less than 1 fJ/μm² . These results demonstrate that QDs within a vertical cavity have great advantages to realize low-powerconsumption polarization-insensitive micrometer-sized switching devices for the future optical communication and signal processing systems.