Poynting vector and beam divergence.

Laser beam divergence was considered using the components of the Poynting vector. A physical interpretation of the real and imaginary parts of the "longitudinal" field component (along the z axis, the direction of beam propagation) is given in an exponential representation. The longitudinal field component was shown to be the reason for the formation of laser beam divergence. This fact was used to reveal fundamental differences between Laguerre-Gaussian beams and incoherent rays in the focal region. The possibility of using selective action on the longitudinal field component to decrease the divergence of Laguerre-Gaussian beams is discussed.

Electromagnetic field equations of the volume plasmon.

The volume plasmon is traditionally defined as a one-dimensional collective oscillation of the free-charge carriers in a metallic volume. Here, we use an alternative approach with the geometry of a lossy Fabry-Perot cavity in a metallic slab. The field equations now show singularities at the plasma resonance, but these can be worked away. We find that the volume plasmon is not purely longitudinal, as in the classical picture; that it does not show evanescence, that its magnetic field is zero, and that at resonance the Fabry-Perot reflectance of the resonant slab equals one. These attributes differentiate the volume plasmon more fundamentally from the surface plasmon than was thought up to now.

Laser resonator supporting a nondiffracting, azimuthally polarized mode.

We analyze the lowest-order mode supported by a laser resonator containing an intra-cavity transmissive axicon using the Fox-Li iteration algorithm. Two configurations were considered. By proper choice of the cavity dimensions, the lowest-order mode is nondiffracting and azimuthally polarized. The mode pattern at the output coupler is a Bessel function of the first order.

Mitigating heat dissipation in Raman lasers using coherent anti-stokes Raman scattering.

We present a novel technique that intrinsically mitigates the quantum-defect heating in Raman lasers. The basic principle of this so-called "coherent anti-Stokes Raman scattering (CARS)-based heat mitigation" is to suppress the phonon creation in the Raman medium by increasing the number of out-coupled anti-Stokes photons with respect to the number of out-coupled Stokes photons. We demonstrate with the aid of numerical simulations that for a hydrogen and a silicon Raman laser, CARS-based heat mitigation efficiencies of at least 30% and 35%, respectively, can be obtained.

Intracavity generation of radially polarized CO2 laser beams based on a simple binary dielectric diffraction grating.

We present experimental results on the intracavity generation of radially polarized light by incorporation of a polarization-selective mirror in a CO(2)-laser resonator. The selectivity is achieved with a simple binary dielectric diffraction grating etched in the backsurface of the mirror substrate. Very high polarization selectivity was achieved, and good agreement of simulation and experimental results is shown. The overall radial polarization purity of the generated laser beam was found to be higher than 90%.

Polarization-selective beam splitter based on a highly efficient simple binary diffraction grating.

A polarization beam splitter (PBS) based on a giant-reflection to zero-order (GIRO) grating is presented. The GIRO grating is a simple binary diffraction grating with parameters chosen such that the excited optical modes in the grating interfere constructively and destructively at the respective interfaces. This interference results in high-zero-order reflection (>99%) with a high polarization-selective extinction ratio (+/-30 dB). The grating shows a low aspect ratio. The GIRO PBS is theoretically and experimentally shown to be an adequate PBS for use as an optical isolator in combination with a quarter-wave plate in a CO2-laser system.

Direct generation of Bessel beams.

Two implementations are identified to create a Bessel beam directly, i.e. without the spatial filtering of an initially Gaussian beam. The first implementation is based on a resonator configuration whose lowest-loss transverse mode is a Bessel beam. Numerical simulation to corroborate the geometrical optical arguments is presented. The second implementation is based on the theorem that the angular-plane wave spectrum of a Bessel beam is composed of a cone of wave vectors. This cone is also generated through a phase-matching condition in a four-wave mixing process. This leads to the conclusion that anti-Stokes radiation generated in a nonlinear material will leave the substrate under the form of a Bessel beam.