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Title: Integrated photonic devices for data communications
Author: Li, Huanlu
ISNI:       0000 0004 5914 5255
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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With the increasing capacity requirements of telecommunication systems, the ability to increase capacity density is of great importance for optical transmission technologies. This thesis presents several integrated photonic devices (semiconductor laser diodes and silicon devices) aimed at boosting the capacity density of the optical transmission systems. The first part of the thesis is about four wave mixing (FWM) effects in semiconductor ring lasers. Mode beating via third order nonlinearity in semiconductor ring lasers has been analysed using a frequency-domain multi-mode rate equation model. Compared with Fabry-Perot lasers, semiconductor ring lasers are found to be 1.33, 2, and 4 times more efficient in self-gain compression, cross-gain compression and four-wave mixing processes, respectively, due to its travelling-wave nature. It is shown that, using dual (pump and signal) external optical injections into the ring laser cavity, multiple modes can be locked in phase via the strong four wave mixing phenomenon. This results in modulation of the light wave at the mode beating frequencies which could be used for RF optical catrier generation. Secondly, following Bristol's research on compact optical vortex beam emitter based on silicon photonic micro-ring resonators, a different approach is demonstrated to simultaneously generate a pair of orbital angular momentum (OAM) modes with opposite topological charge by integrating a micro-ring OAM resonator with simple waveguide devices. The relative phase between two vortices can be actively modulated on the chip by thermo-optical controls. Furthermore, based on the ring cavity structure, OAM ring lasers on AlGaInAs/InP wafer are also developed. Detailed designs, fabrication processes and characterization of the device are discussed. In the last part of the thesis, a new approach is to propose and demonstrate directly generated optical OAM beams, by integrating a micro-scale spiral phase plate (SPP) on top of a vertical-cavity surface-emitting laser (VCSEL). The presence of the multi-level SPP transforms the linearly polarized Gaussian beam to a beam carrying specific OAM modes and their superposition states. The emitted OAM beams are characterized by usmg a spatial light modulator (SLM), and show good agreement with semi-analytical numerical simulation. The innovative OAM emitter opens a new horizon in the field of OAM-based optical and quantum communications, especially for low-cost short reach interconnects.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available