Anisotropic pure-phase plates for quality improvement of partially coherent, partially polarized beams

From a theoretical point of view, the use of anisotropic pure-phase plates (APP) is considered in order to improve the quality parameter of certain partially coherent, partially polarized beams. It is shown that, to optimize the beam-quality parameter, the phases of the two Cartesian components of the field at the output of the APP plate should, be identical and should exhibit a quadratic dependence on the radial polar coordinate

Coherent-mode decomposition of partially polarized, partially coherent sources

It is shown that any partially polarized, partially coherent source can be expressed in terms of a suitable superposition of transverse coherent modes with orthogonal polarization states. Such modes are determined through the solution of a system of two coupled integral equations. An example, for which the modal decomposition is obtained in closed form in terms of fully linearly polarized Hermite Gaussian modes, is given

Beam quality of partially polarized beams propagating through lenslike birefringent elements

Changes generated by lenslike birefringent elements on the beam-quality parameter of partially polarized beams are investigated. Analytical expressions for the beam-quality gain at the output of such systems are given in terms of the second-order intensity moments of the field. Explicit conditions to improve and optimize the beam-quality parameter after propagation through these birefringent transmittances are also shown

Time-resolved spatial profile of TEA CO_2 laser pulses: influence of the gas mixture and intracavity apertures

The evolution of the intensity profile of transversely excited atmospheric CO_2 laser pulses is investigated within the intensity moment formalism. The beam quality factor M_2 is used to study the mode evolution. Attention is focused on the influence of both the gas mixture (N_2:CO_2:He) and the diameter of an intracavity diaphragm placed to attenuate higher-order modes. The degree of accuracy that can be attained by approximating the laser field amplitude by means of the lower-order terms of a Hermite-Gauss expansion is also analyzed. In particular, a bound for the truncation error is given in terms of two time-resolved spatial parameters, namely the beam width and the M_2 parameter