Ian O’ Driscoll
Cork Institute of Technology and Tyndall National Institute, Ireland
Title: Ultrashort optical pulse generation in quantum dot lasers
Biography
Biography: Ian O’ Driscoll
Abstract
This work uses semiconductor quantum dots, which are nanoscale inorganic materials, in order to achieve extremely short optical light pulses. Such pulses find use in high bit rate optical communications, wave division multiplexing, microscopy, multiphoton imaging and the generation of terahertz signal sources. Passively mode locked ultrashort pulses are created using an absorber section within a quantum dot lasing cavity, and the repetition rate, or time between successive pulses, is controlled by the length of the cavity. The work confirms the merits of random population for the generation of ultrashort pulses. When the quantum dots are randomly populated, they are independently occupied, which allows access to the entire gain spectrum. Sub picosecond pulse widths were achieved using these methods, without any significant device engineering. A relatively simple method for significantly improving the optical pulse width when the dots are randomly populated will also be highlighted. These techniques can be applied to any quantum dot material.