Fundamental Research on Quantum Microcavity Lasers

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It is now very important to control completely both electrons and photons for future light emitters to establish systems.In this research project,we have been investigating quantum microcavity lasers in which moth electron and photons are completely controlled by using quantum wires / dots and optical microcavities.First,we investigated fabrication of the quantum wires and dots by MOCVD (Metal Organic Chemical Vapor Deposition). We have obtained GaAs quantum wires with the lateral width of less than 10nm with high quantum efficiency. The photoluminescence and magneto-photoluminescence clearly indicate the existence of the quantum wire effect. The measurement of photoluminescence decay time demonstrates correlation between exciton lifetime and the size of the quantum wire. Strained InGaAs quantum wires are also successfully fabricated. In addition,we fabricated GaAs dot structures using the similar MOCVD method. The smallest structure so far achieved is the quantum dot with the lateral dimension or 25nm. Photoluminescence is obtained from the microstructure.Secondly,microcavity effects are investigated so that the interaction between the exciton and the microcavity mode can be controlled. The measurement of reflectivity spectra demonstrates strong mode coupling between the two mode. This strong mode coupling is corresponding to vacuum-Rabi oscillation.In conclusion,we have studied fundamental issues for future quantum microcavity lasers including fabrication of the quantum wires/dot and interaction between confined excitons and confined photons. The results demonstrated here are useful for further investigation of ultimate light emitters.