Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 6: Photonic crystals I

HL 6.3: Vortrag

Montag, 25. Februar 2008, 10:00–10:15, EW 201

Nonlinear and bistable transmission of high quality factor GaAs photonic crystal cavities — •Martin Garbos, Thomas Sünner, Thomas Schlereth, Sven Höfling, Martin Kamp, and Alfred Forchel — Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg

Two-dimensional photonic crystal (PhC) cavities can localize light in small modal volumes with high quality factors. This leads to a strong enhancement of the field in the cavities, allowing an observation of nonlinear effects at very low power levels of a few µ W. We have studied the nonlinear transmission of PhC cavities based on GaAs membranes. The cavities are realized by small local changes of the geometry (e.g. lattice period or hole diameter) of PhC waveguides. A tunable laser source at 1.55 µ m was used to probe the structures.

The transmission of the cavities has a Lorentzian shape with quality factors of up to 200000 at low power levels. At higher power levels, two photon absorption (TPA) becomes more and more dominant. Most of the generated carriers recombine non-radiatively, leading to an increase of the temperature and the refractice index. The corresponding red-shift of the cavity resonance results in an apparent broadening of the cavity transmission when the tunable laser is swept over the resonance. At a detuning of +10 pm from the resonance, a hysteretic behavious was found when the input power was modulated.