Lars Friedrich

Dynamic, electronically controlled angle steering of spatial solitons in AlGaAs slab waveguides.

We demonstrate experimentally that spatial solitons in AlGaAs slab waveguides can be deflected by an electronically induced prism. We also show that a weak signal beam can be guided and steered by the solitons, thus demonstrating the feasibility of a dynamically reconfigurable optical interconnect.

NONLINEAR DIRECTIONAL COUPLER IN PERIODICALLY POLED LITHIUM NIOBATE

Nonlinear wave propagation was investigated experimentally in coupled waveguides by means of the cascaded nonlinearity in quasi-phase-matched second-harmonic generation. With a specially designed wave-vector-mismatch distribution along the propagation axis, cascading was optimized for low fundamental depletion. High-contrast, ultrafast all-optical switching with switching powers of tens of watts was observed.

Toward soliton emission in asymmetric GaAs/AlGaAs multiple-quantum-well waveguide structures below the half-bandgap.

We report what is to our knowledge the first experimental evidence of nonlinear beam displacement in a strip-loaded GaAs/AlGaAs multiple-quantum-well waveguide with an asymmetric, nonlinear cladding. An intensity-dependent spatial displacement of ~2 mum was observed for the guided mode at a wavelength of 1.55 mum. Numerical simulations that correspond to the experiment are also presented. The device has the potential of providing a soliton-emission-based, ultrafast all-optical switch.

Radiation-related Polarization Instability of Kerr Spatial Vector Solitons

We report the experimental observation and numerical simulations of a polarization instability of spatial vector solitons in an AlGaAs slab waveguide. At power levels where the nonlinear index change becomes comparable to the birefringence, the fast soliton becomes unstable. The instability is related to coupling of the fast soliton to the slow radiation modes through phase matching. The combined effects of bifurcation and radiation coupling are the processes ultimately limiting the stability of any single-polarization (fast and slow) Kerr soliton.

Radiation related polarization instability of fast Kerr spatial solitons in slab waveguides

We report the observation of a power-dependent polarization conversion from a fast spatial soliton-like beam into the orthogonal polarization in an AlGaAs slab waveguide at power levels below which the nonlinear index change becomes comparable to the birefringence. The slow soliton, however, shows no polarization conversion. We interpret these results in terms of the previously predicted polarization instability of a fast soliton into orthogonally polarized radiation. The experimental results are in qualitative agreement with theory.

Linear optical properties of polydiacetylene para-toluene sulfonate thin films

Abstract We report measurements of the dispersion in the linear optical properties (linear absorption coefficient and refractive index) of polydiacetylene para -toluene sulfonate (PDA–PTS) single crystal waveguide films prepared by thermal polymerization of the monomer free floating in solution and subsequent attachment of the film to the substrate. A maximum absorption coefficient >10 5 cm −1 at a wavelength of 620 nm is measured for polarization parallel to the polymer chains, in agreement with previous measurements. The refractive index parallel to the polymer axis is significantly lower in these thin films as compared to bulk PDA–PTS crystals, whereas the index perpendicular to the chains is comparable to that of bulk crystals. Sellmeier parameters describing the dispersion of the refractive index in the near-infrared spectral range are given.

1 x 4 optical interconnect using electronically controlled angle steering of spatial solitons

A novel optical interconnect based on electronically controlled angle steering of spatial solitons is demonstrated experimentally in AlGaAs slab waveguides. The basic operation and the layout of the device are described. A maximal lateral steering of 100 /spl mu/m was achieved, which is sufficient for the separation of four output channels. Using this device as a building block should lend to the experimental realization of dynamically reconfigurable N/spl times/N optical crossconnects.

MULTIPHOTON EFFECTS IN THE POLYDIACETYLENE POLY BIS(P-TOLUENE SULFONATE) OF 2,4-HEXADIYNE-1,6-DIOL (PTS)

Multiphoton absorption was investigated in single crystals of the polymer poly bis(p-toluene sulfonate) of 2,4-hexadiyne-1,6-diol (PTS). Using modified growth and polymerization techniques, high optical quality crystals were grown and their linear absorption spectrum measured. Very large four-photon absorption was measured using Z-scan with a value of α4=0.3 cm5/GW3 obtained at 1600 nm. From the known one and two-photon absorption spectra, the three- and four-photon spectra are predicted to overlap. This leads to three-photon enhanced, four-photon absorption which is interpreted as the mechanism responsible for such large four-photon absorption.

Instability of Fast Kerr Solitons in AlGaAs Waveguides at 1.55 Microns

We observed experimentally a power-dependent polarization instability of the fast spatial soliton in AIGaAs slab waveguides. The slow soliton remains stable. The instability occurs at power levels below which the nonlinear index change becomes comparable to the birefringence and is caused by coupling to radiation fields via four- wave mixing.

High-power second-harmonic generation experiments in periodically poled lithium niobate waveguides

Summary form only given.In centimeter-long quasi-phase-matched (QPM) waveguides for second-harmonic generation (SHG) complete fundamental depletion should be observable at input powers of a few watts. For these and larger powers the fundamental experiences a considerable wave-vector modification. We measured the power-dependence and the spectral behavior of the resulting quadratic cascaded nonlinearity.