Frankfurt 2006 – scientific programme

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Q: Quantenoptik und Photonik

Q 25: Photonische Kristalle II

Q 25.2: Talk

Tuesday, March 14, 2006, 14:00–14:15, HI

Photonic crystal cavities with high quality factors on GaAs membranes — •Thomas Sünner, Rafael Herrmann, Andreas Löffler, Johann-Peter Reithmaier, Martin Kamp, and Alfred Forchel — Technische Physik, Am Hubland, D-97074 Würzburg, Germany

Cavities in photonic crystals (PhCs) can confine light in mode volumes of less than one cubic wavelength with quality factors of several hundred thousand. These properties make PhC cavities very promising candidates for studies of cavity QED and non-linear optics.

We have investigated PhC cavities in GaAs membranes. The layer structure consists of a 250 nm thick GaAs layer on top of a 2µ m thick Al_0.6Ga_0.4As sacrificial layer. The geometry of the cavity is based on a PhC heterostructure [1]. This design uses a variation of the lattice period along a waveguide defined by one missing row of holes (W1) in a hexagonal PhC lattice. The light is confined in a short waveguide section with 410 nm period, sandwiched between ’mirror’ waveguides with 400 nm lattice period. The ’mirror’ waveguides have a stopgap at the wavelength of the cavity resonance and therefore act as reflectors. An access guide connects the cavity to the facets of the sample. The PhC pattern is first etched into the GaAs layer, which is then undercut by selective wet etching of the sacrificial layer.

Transmission measurements were performed using a tunable laser source at 1.5 µ m We have observed cavity resonances with quality factors in excess of 100000.

[1] B.S. Song et al., Nature Materials 4, 207 (2005)