This paper is devoted to experimental and theoretical studies of nonlinear propagation of a long-range surface plasmon
polariton (LRSPP) in gold strip waveguides. The plasmonic waveguides are fabricated in house, and contain a gold layer,
tantalum pentoxide adhesion layers, and silicon dioxide cladding. The optical characterization was performed using a
high power picosecond laser at 1064 nm. The experiments reveal two nonlinear optical effects: nonlinear power
transmission and spectral broadening of the LRSPP mode in the waveguides. Both nonlinear optical effects depend on
the gold layer thickness. The theoretical model of these effects is based on the third-order susceptibility of the constituent
materials. The linear and nonlinear parameters of the LRSPP mode are obtained, and the nonlinear Schrödinger equation
is solved. The dispersion length is much larger than the waveguides length, and the chromatic dispersion does not affect
the propagation of the plasmonic mode. We find that the third-order susceptibility of the gold layer has a dominant
contribution to the effective third-order susceptibility of the LRSPP mode. The real part of the effective third-order
susceptibility leads to the observed spectral broadening through the self-phase modulation effect, and its imaginary part
determines the nonlinear absorption parameter and leads to the observed nonlinear power transmission. The experimental
values of the third-order susceptibility of the gold layers are obtained. They indicate an effective enhancement of the third-order
susceptibility for the gold layers, comparing to the bulk gold values. This enhancement is explained in terms of the
change of the electrons motion.
We study soliton compression in bulk quadratic nonlinear materials at 800 nm, where group-velocity mismatch dominates. We develop a nonlocal theory showing that efficient compression depends strongly on characteristic nonlocal time scales related to pulse dispersion.
We investigate the possibility of using poled silica photonic crystal fibers for self-defocusing soliton compression
with cascaded quadratic nonlinearities. Such a configuration has promise due to the desirable possibility of
reducing the group-velocity mismatch. However, this unfortunately leads to increased phase mismatch, and the
dispersion is often anomalous. All this reduces the design parameter space where soliton compression is possible,
and poses strong requirements on the poling efficiency. We propose to use quasi-phase matching in order to
reach realistic requirements on the quadratic nonlinearity, and show that compression of nJ pulses to few-cycle
duration is possible in such a fiber. A small amount of group-velocity mismatch optimizes the compression.
High-resolution ghost image and ghost diffraction are performed by using a single source of pseudo-thermal speckle light divided by a beam splitter. By only operating on the optical setup of the light in the reference arm, that never interacted with the object, we are able to pass from the image to the diffraction pattern. The product of spatial resolutions of the ghost image and ghost diffraction experiments is shown to overcome a limit which was formerly thought to be achievable only with entangled photons. A complementarity between the spatial coherence of the beams and their mutual correlation is demonstrated by showing a complementarity between ghost diffraction and ordinary diffraction patterns.
We analytically show that it is possible to perform coherent imaging by using the classical correlation of two beams obtained by splitting incoherent thermal radiation. The case of such two classically correlated beams is treated in parallel with the configuration based on two entangled beams produced by parametric down-conversion, and a basic analogy is pointed out. The results are compared in a specific numerical example.