Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 22: Photonic crystals II
HL 22.9: Vortrag
Dienstag, 27. März 2007, 16:15–16:30, H13
Novel photonic bio-sensors based on silicon nanostructures — •Dominic Dorfner, Ulrich Rant, Jonathan Finley, and Gerhard Abstreiter — Walter Schottky Institute, Garching, Germany
Silicon photonic nanostructures are of widespread interest for applications in integrated photonics. In particular, photonic crystal resonators confine light to ultra small volumes and exhibit cavity modes with high optical finesse. We take advantage of these properties to investigate bio-sensor applications based on the linear optical response of the system.
We use a silicon-on-insulator material system to establish 250nm thick freestanding membrane structures perforated with a triangular pattern of air-holes separated by 400nm. By decreasing the diameter of one hole, a cavity with an extremely small mode volume (V< 1/2(λ/n)3 ≈ 0.01 µ m3) is formed. We characterized these structures with µ-photo-luminescence spectroscopy by covering the surface with colloidal PbSe quantum dots embedded in a polymer matrix. First experiments lead to a quality-factor Q ≈ 800 and the dependence on geometric parameters is in excellent agreement to our calculations. Simulations predict a sensitivity of Δ n / n=0.001 to surface refractive index variation in aqueous environment upon covering 10nm of the membrane surface with bio-molecules. Since the sensitive area is in the range of µm2 we predict a sensitivity approaching the single molecule regime.
Photonic crystal waveguide resonators enable bio-functionalization techniques on the surface and offer a unique possibility to carry out research on the interaction of photons with single bio-molecules.