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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Nanooptik

Humboldt-Universität zu Berlin | Mathematisch-Naturwissen­schaft­liche Fakultät | Institut für Physik | Nanooptik | Publications | Interaction of photonic crystals with nanoscopic particles: towards novel (bio)sensing techniques

Michael Barth and Oliver Benson (2006)

Interaction of photonic crystals with nanoscopic particles: towards novel (bio)sensing techniques

In: Photonic Crystal Materials and Devices III, vol. 6182(1), pp. 61821T, SPIE. Proc. SPIE.

We investigate the potential of photonic crystals (PCs) for use as novel sensing devices. For this purpose we study the interaction of nanoscopic dielectric particles with the near field of planar PCs by means of 3D FEM calculations. In particular, we have simulated PC waveguide structures incorporating a single cavity-like defect that interacts with a single dielectric nanosphere in a liquid environment. The resonance of the PC cavity shifts in the presence of the particle, as can be monitored by corresponding transmission measurements. As a second aspect, we investigate the mechanical forces acting on the particle due to the high field gradient in the cavity when in resonance. These forces give rise to a stable trapping of the particle in the cavity in analogy to the trapping in optical tweezers. In combination with microfluidic devices this gives prospect to novel techniques for ultra-sensitive detection and spectroscopy with only minimal amounts of analyte. We also present a scheme for experimental investigations of the particle-PC interaction, which makes use of an optical tweezer to actively move dielectric nanospheres in the near field of the PC, and which allows both for fluorescence as well as very sensitive force measurements.