Henry M. van Driel

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Ballistic pure spin currents are injected into Ge at 295 K using quantum interference between one and two photon absorption processes for 1786 and 893 nm, 200 fs optical pulses. The spin currents are spatially and temporally detected using polarization-and phase-dependent differential transmission techniques with nanometer spatial and femtosecond temporal(More)
— In an earlier publication, preliminary observations of the generation of electrical currents were reported in GaAs and low-temperature-grown GaAs (LT-GaAs) at 295 K using quantum interference control of single-and two-photon band–band absorption of 1.55-and 0.775-m ultrashort optical pulses. Time-integrated currents were measured via charge collection in(More)
Hot electrons are generated in Si(001) at 295 K via linear absorption of .4.3 eV photons or by three-photon processes using 270 fs, 800 nm (1.55 eV) optical pulses. Electron trapping in oxide films is observed via time-dependent optical second harmonic generation induced by the electric field associated with charge transfer. For anodically oxidized samples(More)
We show that, when fundamental optical beams are present in a noncentrosymmetric medium simultaneously with their sum-frequency beam, quantum interference between single-and two-photon transitions modifies the net absorption, if the sum frequency corresponds to an energy greater than the band gap. At a macroscopic level this effect can be related to the(More)
The dynamics of charge currents ballistically injected in GaAs bulk and quantum wells are spatially and temporally resolved. The electrons and holes are injected with oppositely directed velocities without the use of accelerating fields by quantum interference between two photon absorption of a 200 fs, 1430 nm fundamental pulse and one photon absorption of(More)
We report an experimental and theoretical study of the birefringence of two-dimensional photonic crystals in the spectral region below the first photonic band gap. Transmission spectroscopy is used to measure the birefringence of a sample composed of a triangular lattice of air cylinders in silicon, with a cylinder radius of 0.644 ␮m and a lattice pitch of(More)
Transient trapping/detrapping of electrons at the Si͑100͒/SiO 2 outer surface is studied studied in vacuum or with an O 2 ambient ͑between 10 Ϫ3 and 30 Torr͒ following internal electron photoemission from Si. Photoemission-current ͑produced by a 150 fs, 800 nm laser source͒ and contact-potential-difference techniques were used to investigate a wide variety(More)
Photon-induced gas-assisted charging ͑PIGAC͒ of 1.5 nm thick SiO 2 overlayers by photoemission from the Si substrate is demonstrated to be a universal feature for all gases. In our case ͑multi͒photoemission is induced by high-intensity 800 nm, 150 fs pulses in samples at 295 K. O 2 is more effective than other gases, probably due to the accumulation of(More)