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We have investigated the power threshold of discrete Kerr surface solitons at the interface between discrete and continuous 1D AlGaAs medium. Distinct thresholds were measured for interface solitons localized at different sites from the interface.

In this work, the time-domain integration of broadband terahertz (THz) pulses via a tapered two-wire waveguide (TTWWG) is reported. Such a guiding structure consists of two metallic wires separated by a variable air gap that shrinks down to a subwavelength size as the movement takes from the waveguide input to its output. It is shown that while an input THz pulse propagates toward the subwavelength output gap, it is reshaped into its first-order time integral waveform. In order to prove the TTWWG time integration functionality, the THz pulse is detected directly within the output gap of the waveguide, so as to prevent the outcoupling diffraction from altering the shape of the time-integrated THz transient. Since the time-domain integration is due to the tight geometrical confinement of the THz radiation in a subwavelength gap volume, the TTWWG operational spectral range can easily be tuned by judiciously changing both the output gap size and the tapering angle. The results lead to the physical realization of a broadband, analog THz time integrator device, which is envisioned to serve as a key building block for the implementation of complex and ultrahigh-speed analog signal processing operations in THz communication systems.

We observe second harmonic generation via random quasi-phase-matching in a 2.0 micron periodically poled, 1-cm-long, z-cut lithium tantalate. Away from resonance, the harmonic output profiles exhibit a characteristic pattern stemming from a stochastic domain distribution and a quadratic growth with the fundamental excitation, as well as a broadband spectral response. The results are in good agreement with a simple model and numerical simulations in the undepleted regime, assuming an anisotropic spread of the random nonlinear component. (C) 2010 Optical Society of America

We implement a simple and powerful approach to characterize the domain distribution in the bulk of quadratic ferroelectric crystals via far-field second-harmonic spectroscopy. The approach is demonstrated in a lithium tantalate sample with periodic electric field poling and random mark-to-space ratio.

We present our investigation on the THz space-time emission characteristic induced by the non-paraxial generation regime in highly localized THz generation via optical rectification on sub-wavelength areas.

A highly localized THz source is a promising candidate for sub-wavelength microscopy, due to its superior radiation power throughput with respect to others near-field techniques. Here, we report on the spatial and the spectral near-field properties of our highly localized THz source.

We introduce and test a simple approach for the characterization of domain distribution in bulk quadratic ferroelectric crystals, such as periodically poled Lithium Tantalate with random mark-to space ratio.

We demonstrated broadband second-harmonic generation via random Quasi-Phase-Matching in periodically poled Lithium Tantalate.

We report on the observation of Type I third-harmonic generation induced by a train of femtosecond laser pulses in nematic liquid crystals. We find that as the average power of the train is increased, the frequency conversion process is enhanced as a consequence of the tight confinement of the pulses into a nonlocal spatial soliton. (C) 2010 Optical Society of America

We demonstrate a parametric interaction based on four wave mixing that can arrest the collapse and stabilize solitary propagation in a pure Kerr material by controlling the wavelength of the interacting beams.

We investigate four-wave mixing between terahertz and optical pulses in diamond. We observe the occurrence of sum and difference frequency generation, with the latter being phase-matched for terahertz pulses counter-propagating to the optical field.

We experimentally observed and explained bulk second harmonic generation via random quasi-phase-matching, derived from a periodically poled lithium tantalate sample with a randomly patterned mark-to-space-ratio.