Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors.

FOM Institute for Atomic and Molecular Physics (AMOLF), Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
The Review of scientific instruments (Impact Factor: 1.52). 08/2009; 80(7):073104. DOI: 10.1063/1.3156049
Source: PubMed

ABSTRACT We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21,050 cm(-1). A broad pump scan range allows a large optical penetration depth, while a broad probe scan range is crucial to study strongly photonic crystals. A new data acquisition method allows for sensitive pump-probe measurements, and corrects for fluctuations in probe intensity and pump stray light. We observe a tenfold improvement of the precision of the setup compared to laser fluctuations, allowing a measurement accuracy of better than DeltaR=0.07% in a 1 s measurement time. Demonstrations of the improved technique are presented for a bulk Si wafer, a three-dimensional Si inverse opal photonic bandgap crystal, and z-scan measurements of the two-photon absorption coefficient of Si, GaAs, and the three-photon absorption coefficient of GaP in the infrared wavelength range.

  • [Show abstract] [Hide abstract]
    ABSTRACT: We study frequency-resolved femtosecond pump-probe reflectivity of a planar GaAs-AlAs microcavity. About 8 ps after a pump pulse, we observe a strong excess probe reflectivity. Light trapped in the cavity accumulates a phase change due to a time-dependent refractive index, resulting in a change in frequency by more than 5 linewidths away from the cavity resonance. The frequency change is non-adiabatic as the electromagnetic field distribution changes shape in time and the rate of change of the cavity resonance is fast. An analytical model predicts dynamics in agreement with experiments, and points to crucial parameters that control future applications.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this thesis we demonstrate the control of the emission of light at near-infrared wavelengths. To this end we use PbSe quantum dots inside titania inverse opal photonic crystals. We introduce our research field and elaborate on the new-built experimental setup. Subsequently, technical aspects on the PbSe quantum dots and on time correlated single photon counting at near-infrared wavelengths are discussed. For different sizes of PbSe quantum dots absorption oscillator strengths of 6.9 and 10 were found, which are approximately 7.5 times larger than the measured emission oscillator strengths. We found the oscillator strength to increase with quantum dot size, giving rise to an increase of the spontaneous emission rate with size. The absorption cross-sections of our quantum dots are determined from transmission measurements which yield sizes of 10E−15 to 10E−16 cm^2. We have measured the frequency-dependent escape function of the quantum dot emission. The results are compared with an escape-function model that is based on diffusion theory and extended to photonic crystals. Strong deviations from the Lambertian emission profile are observed. An attenuation of 60 % is observed in the angle dependent power emitted from the samples, due to photonic stop bands. At angles that correspond to the edges of the stop band the emitted power increased by up to 34 %. This increase is explained by the redistribution of Bragg-diffracted light over the available escape angles. In addition we controlled the spontaneous emission rate via de Local Density of Optical States by changing the lattice parameter of the photonic crystal. We found an inhibition of the emission rate up to 51 % and an enhancement up to 29 %, as compared to the decay rates measured from non-photonic reference samples. Our experimental results agree with earlier measurements in the visible range, and are qualitatively explained using DOS-calculations. Finally we discuss the experimental method that was developed to recover a single, deterministically fabricated nanostructure in various experimental instruments without the use of artificially fabricated markers, with the aim to study photonic band gap structures with cavities.
    PhD Thesis. 05/2009;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have performed ultrafast pump–probe experiments on a GaAs–AlAs microcavity with a resonance near 1300 nm in the "Original" telecom band. We concentrate on ultimate-fast optical switching of the cavity resonance that is measured as a function of pump-pulse energy. We observe that, at low pump-pulse energies, the switching of the cavity resonance is governed by the instantaneous electronic Kerr effect and is achieved within 300 fs. At high pump-pulse energies, the index change induced by free carriers generated in the GaAs start to compete with the electronic Kerr effect and reduce the resonance frequency shift. We have developed an analytic model that pre-dicts this competition in agreement with the experimental data. To this end, we derive the nondegenerate two-and three-photon absorption coefficients for GaAs. Our model includes a new term in the intensity-dependent refractive index that considers the effect of the probe-pulse intensity, which is resonantly enhanced by the cavity. We calculate the effect of the resonantly enhanced probe light on the refractive index change induced by the electronic Kerr effect for cavities with different quality factors. By exploiting the linear regime where only the electronic Kerr effect is observed, we manage to retrieve the nondegenerate third-order nonlinear susceptibility χ …3† for GaAs from the cavity resonance shift as a function of pump-pulse energy.
    Journal of the Optical Society of America B 01/2012; 29(9):2630-2642. · 2.21 Impact Factor

Full-text (2 Sources)

Available from
May 19, 2014