PhD Defence by Jakob Rosenkrantz de Lasson

Modeling and simulations of light emission and propagation in open nanophotonic systems



Assoc. Prof. Niels Gregersen, DTU Fotonik



Prof. Jesper Mørk, DTU Fotonik

Postdoc Philip T. Kristensen, Humboldt-Universität zu Berlin, Germany


Evaluation Board
Assoc. Prof. Andrei Lavrinenko, DTU Fotonik
Prof. Stephen Hughes, Queen’s University, Canada
Assoc. Prof. Thomas Søndergaard, Aalborg University

Master of the Ceremony
Assoc. Prof. Martijn Wubs, DTU Fotonik

Light emission and propagation in photonic crystal membranes are studied theoretically, with an emphasis on waveguides, slow light effects, and coupled cavity-waveguide systems.

A photonic crystal waveguide with side-coupled cavities is considered, and the local density of states (LDOS) is described using a semi-analytical quasi-normal mode theory. Comparing to numerically exact calculations, the theory correctly predicts a slight asymmetry (one cavity) and a peak and a dip (two cavities) in the LDOS spectra.

Next, the photonic crystal waveguide is interfaced with a side-coupled cavity and a scattering site, and we demonstrate that the shape of the transmission spectrum can be controlled by the cavity-scattering site distance, for example to exhibit asymmetric Fano shapes. Subsequently, we investigate an active photonic crystal waveguide in the slow light region and present an original coupled Bloch mode model. We show that this gives rise to distributed feedback, which puts fundamental limitations on the maximum achievable gain.

Finally, dipole emission in photonic crystal membrane waveguides is analyzed, where we design slow and fast light waveguides for enhanced single-photon emission. We find that the relative coupling into the guided mode remains in excess of 50%, even in non-optimum situations, and quickly approaches unity towards the band edge. Preliminary experimental results demonstrate emission from position-controlled quantum dots into the waveguide mode.




Wed 16 Dec 15
13:30 - 16:30


DTU Electro


Lyngby Campus

Building 341, auditorium 22