Theoretical And Experimental Study On Nano Wire Quantun Dot Single Photon Sources

Single photon source is one of the key devices in quantum communication and quantum computing. From the point of view of generation, single photon emission can be observed from single atom or some kinds of atomic system under optical or electrical excitation. Single quantum dot, as a typical type of atomic system, can generate single photon in the strict sense. However, the application of single quantum dot is limited because of its low spontaneous radiation efficiency and random emitting directions. One efficient way to solve the problem is to embed the single quantum dot into a micro cavity to improve the spontaneous emission efficiency and achieve directional single photon emitting.Nanowire is a natural cavity and easy to be integrated with quantum dots.Single-photon sources based on nanowire/quantum dot structures have important application prospects. In this thesis, we have carried out theoretical and experimental research on nanowire quantum dot single-photon sources. The main achievements are as follows:1. The optical properties of a single photon source based on a single InAs quantum dot embedded in a GaAs/InP core-shell nanowire are simulated by finite-difference time-domain method. The influence of nanowire radius, length and the position of quantum dot on the Purcell factor and extraction efficiency of the quantum dot emission is investigated.2. A single photon source structure based on gold-encapsulated nanowire quantum dot is proposed and simulated. The influence of nanowire radius and gold thickness on the emission properties of quantum dot is investigated. At a nanowire dimeter of 25 nm and gold shell thickness of 75 nm, the Purcell factor is 1028 times higher than that without gold, providing a way to further reduce the size of the device.3. Isolated quantum dots are grown on the GaAs/InP core-shell nanowire sidewalls by metal organic chemical vapor deposition. The quantum dots are grown in the S-K mode and exhibit pure zinc blende crystal structure. At 5.5 K, the quantum dot exhibits a distinct emission peak at 1.37-1.39 eV, and the spectral linewidth is varying from several hundred ?eV to 1 meV. The structure is promising in near-infrared single photon sources.