Orange surface waveguide laser in Pr:LiYF produced by a femtosecond laser writing.

Depressed-cladding surface channel waveguides were inscribed in a 0.5 at.% Pr:LiYF crystal by femtosecond Direct Laser Writing.

Red Sm:KGd(WO) laser at 649 nm.

We report on the first laser operation of a Sm-doped monoclinic KGd(WO) double tungstate crystal in the red spectral range. Pumped by a frequency-doubled optically pumped semiconductor laser (2ω-OPSL) at 479.1 nm, the 0.

Interferometric images of irregular rough particles in the presence of time-dependent index inhomogeneities in front of the imaging system.

A digital micromirrors device is used to reproduce the speckle-like interferometric images that would produce rough particles. Time-dependent index inhomogeneities induced by a flame are added between the particle and the imaging system. The size measurements deduced from 2D-Fourier analysis of the interferometric patterns show a less than 10% error when the programmed object is fixed, and a less than 20% error when a scintillation of the object is programmed.

Extended focus depth for Gaussian beam using binary phase diffractive optical elements.

A novel technique to improve the focus depth of a Gaussian beam is presented in this paper. The improvement is based on two-step beam shaping using a cascade of binary phase diffractive optical elements (BPDOEs). The first BPDOE transforms the incident Gaussian beam into a high-order radial Laguerre-Gaussian beam (LG).

Generation of Laguerre-Gaussian LGp0 beams using binary phase diffractive optical elements.

In recent years, considerable attention has been devoted to laser beams with specific intensity profile, i.e., non-Gaussian.

Reconstruction-free sensitive wavefront sensor based on continuous position sensitive detectors.

We propose a new device that is able to perform highly sensitive wavefront measurements based on the use of continuous position sensitive detectors and without resorting to any reconstruction process. We demonstrate experimentally its ability to measure small wavefront distortions through the characterization of pump-induced refractive index changes in laser material. In addition, it is shown using computer-generated holograms that this device can detect phase discontinuities as well as improve the quality of sharp phase variations measurements.

Spatial properties of coaxial superposition of two coherent Gaussian beams.

In this paper, we explore theoretically and experimentally the laser beam shaping ability resulting from the coaxial superposition of two coherent Gaussian beams (GBs). This technique is classified under interferometric laser beam shaping techniques contrasting with the usual ones based on diffraction. The experimental setup does not involve the use of some two-wave interferometer but uses a spatial light modulator for the generation of the necessary interference term.

Transverse superresolution technique involving rectified Laguerre-Gaussian LG(p)⁰ beams.

A promising technique has been proposed recently [Opt. Commun. 284, 1331 (2011), Opt.

Baryscan: a sensitive and user-friendly alternative to Z scan for weak nonlinearities measurements.

A new and efficient technique for measuring weak optical nonlinearities is reported. Like Z scan, its implementation is basic, both experimentally and theoretically, but leads to an improved sensitivity of λ/5.10⁴, which represents, to date, one of the highest observed enhancements.

Variant of the method of Fox and Li dedicated to intracavity laser beam shaping.

We present a variant of the method of Fox and Li [Bell Syst. Tech. J.

Cascades of pi-phase plates: a transparent diffractive focusing system.

Typically, refractive lenses are used to focus rays of light, but an alternative way can be found by exploiting diffraction of light. It is well known that cascades of hard-edge apertures are able to focus light but with the great drawback of absorption losses. In this paper, we demonstrate that replacing hard-edge apertures with pi-phase plates within a cascade greatly improves the focusing of collimated Gaussian beams.

Modeling the propagation of apertured high-order Laguerre-Gaussian beams by a user-friendly version of the mode expansion method.

The mode expansion method (MEM) models the propagation of an apertured beam by expressing the diffracted field as a finite series of Laguerre-Gaussian or Hermite-Gaussian modes. An optimal expansion parameter set (beam waist of the modes and its location) reduces the number of modes, which is difficult to derive, especially for high-order incident beams. We propose a user-friendly version of the MEM in which the expansion parameter set and the suitable number of modes are simply deduced from the approximation of the apertured incident beam.

Adaptive Laguerre-Gaussian variant of the Gaussian beam expansion method.

A variant of the Gaussian beam expansion method consists in expanding the Bessel function J0 appearing in the Fresnel-Kirchhoff integral into a finite sum of complex Gaussian functions to derive an analytical expression for a Laguerre-Gaussian beam diffracted through a hard-edge aperture. However, the validity range of the approximation depends on the number of expansion coefficients that are obtained by optimization-computation directly. We propose another solution consisting in expanding J0 onto a set of collimated Laguerre-Gaussian functions whose waist depends on their number and then, depending on its argument, predicting the suitable number of expansion functions to calculate the integral recursively.

Improvement of the self-Q-switching behavior of a Cr:LiSrAlF6 laser by use of binary diffractive optics.

It has been shown experimentally and theoretically that Q-switching behavior is possible in a flashlamp-pumped Cr-doped LiSrAlF6 (Cr3+:LiSAF) laser that consists only of two mirrors, a laser crystal, and a diaphragm. We demonstrate that insertion into a laser of a binary diffractive optical element can speed up the dynamics of the self-Q-switched laser such that the output pulse is shortened (from 60 to 33 ns) and its energy is increased (from 36 to 54 mJ). The self-Q-switching behavior of the laser has the ability to produce a laser pulse with a duration that one can adjust continuously from 60 to 700 ns just by opening the diaphragm.