Robert Iwanow

Observation of discrete quadratic surface solitons

We report the first observation of discrete quadratic surface solitons in self-focusing and defocusing periodically poled lithium niobate waveguide arrays. By operating on either side of the phase-matching condition and using the cascading nonlinearity, both in-phase and staggered discrete surface solitons were observed. This represents the first experimental demonstration of staggered/gap surface solitons at the interface of a semi-infinite nonlinear lattice. The experimental results were found to be in good agreement with theory.

Enhanced third-order nonlinear effects in optical AlGaAs nanowires

We report the first observation of enhanced third-order nonlinear effects in AlGaAs nanowires. AlGaAs nanowaveguides with widths varying from 100 to 600nm were fabricated and characterized. Nonlinear phase shifts of approximately pi were experimentally observed at 1.55mum with peak powers of 30-40W in 600mum long, 550nm wide guides.

OBSERVATION OF ONE- AND TWO-DIMENSIONAL DISCRETE SURFACE SPATIAL SOLITONS

The recent theoretical predictions and experimental observations of discrete surface solitons propagating along the interface between a one- or two-dimensional continuous medium and a one- or two-dimensional waveguide array are reviewed. These discrete solitons were found in second order (periodically poled lithium niobate) and third order nonlinear media, including AlGaAs, photorefractive media and glass, respectively.

Spatial ultrafast switching and frequency conversion in lithium niobate waveguide arrays

We demonstrate phase-insensitive, ultrafast, all-optical spatial switching and frequency conversion in quadratically nonlinear waveguide arrays in periodically poled lithium niobate. Routing of milliwatt signals with wavelengths in the communication band (1550 nm) is achieved without pulse distortions by parametric interaction with a control beam with 10-W power and wavelengths near 775 nm.

One-dimensional spatial soliton families in optimally engineered quasi-phase-matched lithium niobate waveguides

The advantage for quadratic soliton generation of engineering the quasi-phase-matching period near the input of lithium niobate slab waveguides is demonstrated. This approach allows members of one-dimensional quadratic soliton families with different values of the wave-vector mismatch to be cleanly excited and to be characterized by quantitative intensity-profile measurements of both the fundamental and the second-harmonic soliton components.

Discrete modulational instability in periodically poled lithium niobate waveguide arrays

Parametric gain associated with discrete modulational instability due to the second order nonlinearity chi(2)(-2omega;omega,omega) was investigated experimentally in periodically poled lithium niobate arrays of weakly coupled channel waveguides for conditions of both positive and negative phase-mismatch for second harmonic generation.

Highly localized discrete quadratic solitons.

We observe highly localized solitons in periodically poled lithium niobate waveguide arrays close to phase matching for second-harmonic generation. With fundamental and second-harmonic input in one channel the response indicates two distinguishable propagation schemes. Depending on the relative phase between the two input waves, a self-trapped beam emerges, resembling closely either the in- or the out-of-phase quadratic eigenmode of a single waveguide. A stable soliton propagates when the input waves are in phase.

Low-power, multiport, ultrafast, parametric switching in cascaded waveguide couplers

We explore an approach to multiport, phase-insensitive all-optical switching of milliwatt power signals based on linear coupling in cascaded directional couplers and on nonlinear parametric gain via the second-order nonlinearity. For the basic unit, a two-core coupler, we experimentally demonstrated ultrafast transparent switching of 1550nm signals triggered by 5-ps-long control pulses at ≈775nm with a peak power of 1.3W. Theoretically, we show that this concept has the potential for terabit/s switching with a few picojoules control energy and without pulse degradation.

Discrete quadratic interface solitons

We report the first experimental observation of discrete quadratic interface solitons existing at the edge of a PPLN waveguide array. Both in-phase and staggered discrete surface solitons were observed.

Nonlinear Surface Waves at the Interface of Discrete and Continuous Media

We provide an overview of recent theoretical and experimental results in the area of surface lattice solitons. The observation of these waves in Kerr and quadratic nonlinear periodic structures is discussed