Analysis of laser sources for the generation of low repetition rate optical pulses for pumping single photon source

Inside this thesis, a Multi-Section Delayed Differential Equation model has been used to perform the numerical analysis of a passively mode locked quantum dot lasers produced by the german company Nanoplus Nanosystems and Technologies GmbH. In particular, the device analyzed has been created for pumping single photon source and so it's characterised by a very low repetition rate (extremely long cavity) which makes quite trivial its analysis. We've started by providing the theoretical background required to model the QD-based lasers focussing our attention mainly: on the QD electronic structure, on their features and on their rate equations (both under current injection and under reverse voltage). After this we've passed into the description of the Mode Locking, explaining its working principle and showing the most used technology (active, passive and hybrid) providing a detailed description of the passive one. Inside this section we've also presented the main advantages related to the usage of QD material (as well as the actual state of the art) and also the main problem related to the generation of optical pulses with a low repetition rate. To fully contestualize our work we've at this point provided some notions on the single photon source pumping. In particular, we've examined the main parameters that characterize a single photon source and we've also presented the main structures used for this purpose and the different ways of pumping such sources. Before moving on to the most experimental part of the thesis, we've provided a complete description of the MS-DDE presenting also all the features included in the model and evaluating the impact of the temporal and spatial discretization. Once anything has been correctly introduced and defined, we have moved on with the actual fitting of the datas provided by the company Nanoplus Nanosystems and Technologies GmbH. Firstly, by properly chosing all the parameters required by the simulator, we focused on the fit of both electronic and physical structure of such device. Then, the simulated results have been presented and deeply commented and a comparison of the performances of the two devices has been carried out. Then, the laser source have been slightly modified and some variations of this device have been investigated in order to better evaluate the devices' operation at repetition rates even lower than the considered one. Finally, at the end of the thesis, the conclusions were drawn.