We demonstrate all-optical switching in an active two-dimensional photonic crystal waveguide, observing as large as 16 nm blueshifts of a leaky eigenmode at 839 nm and switching ratios of almost 70%. These results are larger than those previously observed in similar experiments performed on passive photonic crystal waveguides; the enhancement is due to resonant photogeneration of carriers by In(0.12)Al(0.2)Ga(0.68)As quantum wells in the core of the waveguide. The effective change in the refractive index of the structure is approximately10(-2), with a rise time of approximately1 ps and a decay time of approximately10 ps, potentially allowing high-speed switching and fast modulation rates.
Light amplification by stimulated Raman scattering in AlGaAs-based photonic-crystal line-defect waveguides Appl. Phys. Lett. 93, 051114 (2008); 10.1063/1.2965110 Nonlinear AlGaAs waveguide for the generation of counterpropagating twin photons in the telecom range J. Appl. Phys. 98, 063103 (2005); 10.1063/1.2058197Ultrafast nonlinear tuning of the reflection properties of AlGaAs photonic crystal waveguides by two-photon absorption
We have studied the power-dependent wavelength shift of photonic coupling resonances of a two-dimensional photonic crystal waveguide by reflection geometry pump-probe measurements. The quadratic response is indicative of two-photon induced carrier creation, which alters the refractive index of the semiconductor core of the photonic lattice. A free-carrier model is used to simulate the phenomenon, giving values of the change in refractive index per unit carrier density that satisfactorily compare to values calculated for bulk AlGaAs under similar conditions. Time-resolved spectra are also presented, showing relaxation times of Ͻ10 ps which are consistent with surface recombination times in the patterned waveguide.
We report an ultrafast optical tuning of the reflectivity of Al x Ga 1−x As/ In y Al x Ga 1−x−y As multiple quantum well photonic crystal waveguides using a reflection geometry, pump-probe technique. Nonlinear shifts of the photonic resonances between 800 and 900 nm are demonstrated with a measured response time of ϳ300-400 fs. The nonlinear shift is attributed to virtual carriers, with the response time determined by the pump pulse duration. This demonstrates ultrafast photonic switching in a high-contrast photonic structure based on III-V quantum wells.
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