Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.


Local probing of Bloch mode dispersion in a photonic crystal waveguide

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Rob J.P. Engelen, Tim J. Karle, Henkjan Gersen, Jeroen P. Korterik, Thomas F. Krauss, Laurens Kuipers and Niek F. van Hulst
Optics Express
Vol. 13, No. 12 p4457 - p4464 june 13 2005

The local dispersion relation of a photonic crystal waveguide is directly determined by phase-sensitive near-field microscopy. We readily demonstrate the propagation of Bloch waves by probing the band diagram also beyond the first Brillouin zone. Both TE and TM polarized modes were distinguished in the experimental band diagram. Only the TE polarized defect mode has a distinctive Bloch wave character. The anomalous dispersion of this defect guided mode is demonstrated by local measurements of the group velocity. The measured dispersion relation and measured group velocities are both in good agreement with theoretical calculations.
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