John Donegan

Photonics, Trinity College Dublin

I am an Associate Professor of Physics and Principal Investigator in CTVR, the Telecommunications Research Centre and in CRANN, the Nanoscience Research Centre in Trinity College Dublin.My Research interests include: Microcavity structures for nonlinear optical inter- actions; Tunable diode lasers based on slotted Fabry-Perot structures;Integrated laser and optical modulator structures; CdTe nanocrystals and nanowires as novel photon emitters; Single and coupled Microsphere resonators; Conical refraction of light.

School of Physics,
Trinity College,
Dublin 2,



The Research Team

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My Current Research Group Includes:

Research Fellows: Dr. Yury Rakovich, Dr. Wei-Hua Guo, Dr. Qia-oyin Lu, Mr. Michael LynchResearch Students: Mr. Edward Flood, Ms. Aliaksandra Rakovich, Mr. David O’Dwyer, Mr. Ciaran Phelan, Mr. David McCloskey, Mr. Kevin Morrison, Ms. Marta Nawrocka, Mr. Azat Abdullaev, Mr. Kyle Ballantine.

Research Interests

My groups research interest in Optical Communications are:
Slotted Fabry-Perot Lasers: We have designed a new structure based on etched slots to produce a verner-tuned semiconductor laser. We have also designed a facetless single mode laser suitable for photonic integration. Mach-Zehnder modulators and high speed photodiodes: We have designed the passive waveguide structure to be integrated with our tunable laser design and to operate at speeds upto 40GHz.
My groups’ research interests in Nanophontics are within two main areas:
Quantum Dot Interactions: We have been studying fluorescent quantum dot system synthesized through colloidal processes. We are investigating energy transfer processes in hybrid systems involving quantum dots and other nanoscale systems. We have looked at transport of quantum dots in cells and how these dots interact to form quantum wire structures. Recently, we have studied energy transfer processes in three systems, all containing colloidal semiconductor quantum dots (QDs) as one of the components. Energy transfer processes with methylene blue (MB), bacteriorhodopsin protein (bR) and photosynthetic reaction centres (RC) extracted from bacterial membranes were studied.

Microcavity Interactions: We investigate mechanisms in coupled photonic micro-resonators which result in modified properties, such as directional emission, modification of the modal structure, and localized field confinement. These properties are desirable in nanophotonic systems and the use of coupled resonators may provide a means to tune these properties. We focus on two aspects: Photonic Jets, a focusing property of spherical and cylindrical resonators and mode manipulation in Photonic Molecules.