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We demonstrate a muW-level broadly tunable THz source based on parametric down-conversion in orientation-patterned GaAs pumped by femtosecond pulses from a Tm-doped fiber laser. Generated THz powers should be scalable to mW-levels with this approach.
Time-resolved mid-infrared-pump, optical-probe differential transmission spectroscopy directly reveals electron dynamics in n-doped quantum dots infrared detector structure. Capturing and intradot relaxation time were measured. Nanosecond-scale dynamics in the n=1 state was also observed.
Experimental studies of the electron and hole concentration dynamics in the barrier of GaSb-based type-II quantum-well (QW) heterostructures was performed. Difference between electron and hole relaxation rates is explained by corresponding QW carrier confinement energies.
The gain and index dynamics of a QD amplifier operating at 1.55 mum are characterized via heterodyne pump-probe measurements with 150 fs resolution. A 13 ps gain recovery time was found, promising for all-optical signal processing.
We report on the generation of 550 mW of 460 nm blue radiation by single pass frequency doubling the picosecond pulses of a mode-locked InGaAs diode laser MOPA system in periodically poled KTP.
The spectral width of terahertz emission from ion-implanted terahertz emitters increases with ion damage, owing to ultrafast carrier capture. Carrier dynamics simulations reinforce these findings. Optical-pump, terahertz-probe experiments confirm the sub-picosecond lifetimes of these materials.
The spin relaxation within the radiative doublet of the exciton ground state in InAs/GaAs quantum dots is studied via ultrafast spectral hole burning spectroscopy. A biexcitonic resonance emerges due to relaxation of the exciton spin.
The feasibility of using femtosecond laser micro-machining to create Gallium Arsenide (GaAs) quasi-phasematched devices from single GaAs wafers is investigated. We describe machining of the structure and details of the machining quality achievable in GaAs.
We demonstrate the picosecond switching in 1D AlGaAs photonic crystal waveguides. We show the decay times vary with the structure parameters demonstrating excellent potential for ultrafast nonlinear switches with a controllable recovery time.
The role of polarons in the quantum kinetics of carrier-phonon interaction is emphasized. Scattering processes involving polarons allow ultrafast relaxation even if the phonon energy is not resonant with the electronic transitions.
We report the wavelength dependences of the two- and three-photon absorption coefficients and nonlinear refractive indices of undoped GaAs in the spectral range 1.3-3.5 mum. We have used 100-fs-long optical pulses and the Z-scan method.
We present time-resolved reflectivity spectra of optically, homogeneously switched photonic crystals. We observe large, ultrafast shifts of stopbands of GaAs/AlAs multilayer structures as well as in the photonic bandgap range of 3D Si inverse opals.
Ballistic pure spin currents generated via quantum interference in the absorption of femtosecond pulses are demonstrated to produce transverse ballistic Hall pure charge currents and vice versa via spin-dependent asymmetric scattering processes.
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