Thermodynamical Analysis of the Formation of -Si Ring Structures on Silicon Surface.

Superficial modifications on silicon wafers produced by single-shot focused femtosecond laser irradiation having a 1030 nm wavelength and 300 fs pulse duration were experimentally and theoretically analyzed. The laser fluence window when the amorphous silicon phase develops, resulting in a ring-like modification shape, was experimentally estimated to be between 0.26 J/cm2 and 0.

Performance investigation of high-efficiency widely tunable subnanosecond optical parametric generator and amplifier based on MgO:PPLN.

We report on experimental and theoretical studies of widely tunable high-efficiency subnanosecond optical parametric generator (OPG) and amplifier (OPA) based on a 2 cm long multigrating MgO-doped periodically-poled lithium niobate (MgO:PPLN) crystal pumped by a passively Q-switched Nd:YAG micro-laser. Our OPG can be continuously tuned from 1442 nm to 4040 nm with signal wave energies ranging from 33 J to 265 J and total OPG conversion efficiency up to 46 % that depended on the pump focusing conditions. Characterization of spatial properties of the OPG determine Lorentzian spatial profile of the signal beam with ≈2 that was also dependent on the pump focusing conditions.

Measurement of the phase refractive index of a photonic crystal fiber mode.

We present a new experimental technique for measurement of the refractive index of a photonic crystal fiber (PCF) fundamental mode. We demonstrate that the phase refractive index of the PCF mode can be estimated by analyzing a phase shift of interfering adjacent longitudinal laser modes of a continuous-wave laser corresponding to a shift from constructive to destructive interference. The experimental results are in very good agreement with numerically simulated phase refractive index values.

Estimation of photonic crystal fiber dispersion by means of supercontinuum generation.

We present a technique for photonic crystal fiber dispersion measurement. We demonstrate that investigating supercontinuum using cross-correlation frequency resolved optical gating (XFROG) technique can be used for quantitatively characterizing dispersion and observing orthogonal polarization modes in polarization maintaining photonic crystal fibers. In addition, an XFROG trace of supercontinuum generated in a polarization maintaining photonic crystal fiber reveals complex behavior of orthogonal polarization modes that is different in normal and anomalous dispersion regions of the photonic crystal fiber.

Generation and control of the spiraling zero-order Bessel beam.

We report on the generation of a spiraling zero order Bessel beam by means of conventional axicon and the phase hologram. Obtained results are in a fairly good agreement with the theoretical predictions.