Person: Mejías Arias, Pedro Miguel
Universidad Complutense de Madrid
Faculty / Institute
Now showing 1 - 10 of 36
- PublicationBeam quality in monomode diode-lasers(Chapman & Hall Ltd., 1992-09) Serna Galán, Julio; Martínez Herrero, Rosario; Mejías Arias, Pedro MiguelAn analytic and measurable beam parameter is defined for beams emerging from heterojunction monomode diode lasers with very thin active layers, which provides a joint description of their focusing capabilities and far field divergence behaviour. This parameter can be of use as a figure of merit to compare either the output responses of this type of laser or the different optical systems employed to modify the laser beam. The minimum value of this parameter is determined. Also, it is shown that the beams emitted by these lasers cannot be transformed into circularly symmetric ones by any ABCD optical system. Finally, the possibility of achieving circularly symmetric intensities (at least to second order) and/or beam collimation at some plane is investigated, and its connection with the coupling efficiency between a monomode diode laser and an optical fibre is pointed out.
- PublicationQuality improvement of partially coherent symmetric-intensity beams caused by quartic phase distortions(The Optical Society of America (OSA), 1992-12-01) Piquero Sanz, Gemma María; Martínez Herrero, Rosario; Mejías Arias, Pedro MiguelThe effects that quartic phase distortions produce in the beam-quality parameter of partially coherent symmetric-intensity beams are studied. An analytical expression for the beam-quality parameter at the output plane of a pure phase plate with quartic phase aberration has been derived. Explicit conditions to improve the beam quality are provided, and the corresponding optimized beam-quality value that can be attained for a given field has been determined.
- PublicationRotation of partially coherent beams propagating through free space(Chapman & Hall Ltd., 1992-09) Serna Galán, Julio; Martínez Herrero, Rosario; Mejías Arias, Pedro MiguelThe orientation of a general partially coherent beam is described by introducing two pairs of orthogonal axes defined in terms of the second-order coherence features of the field. A general classification scheme for light beams is presented, based on their rotational behaviour under free propagation. This behaviour could be inferred from the values of certain measurable parameters at some plane. As an example of interest, the above classification is applied to Gaussian (coherent) beams with general astigmatism.
- PublicationPropagation of laser beam parameters through pure phase transmittances(Elsevier Science BV, 1996-08-15) Piquero Sanz, Gemma María; Mejías Arias, Pedro Miguel; Martínez Herrero, RosarioThe propagation laws of the intensity moments of a laser beam through ABCD optical systems are generalized to include pure phase transmittances. This is done by representing the behaviour of such transmittances by means of a 4 x 4 matrix, hi, which can be handled, to some extent, as the ABCD-matrices associated with ordinary first-order optical systems. This formalism enables the application of ABCD propagation formulae to cascaded optical systems containing pure phase transmittances. Matrix M is used to determine the intensity moments at the output of two special quartic phase transmittances, namely, a circular spherically aberrated lens and a pair of orthogonal cylindrical (also aberrated) lenses.
- PublicationBeam quality of partially polarized beams propagating through lenslike birefringent elements(Optical Society of America, 1999-11) Piquero Sanz, Gemma María; Movilla Serrano, Jesús María; Mejías Arias, Pedro Miguel; Martínez Herrero, RosarioChanges 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.
- PublicationAnisotropic pure-phase plates for quality improvement of partially coherent, partially polarized beams(Optical Society of America, 2003-03) Piquero Sanz, Gemma María; Martínez Herrero, Rosario; Mejías Arias, Pedro MiguelFrom 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.
- PublicationSpatial characterization of the transversal structure of rotationally symmetric pulsed beams(Chapman & Hall Ltd., 1997-09) Encinas Sanz, Fernando; Serna Galán, Julio; Mejías Arias, Pedro Miguel; Martínez Herrero, Rosario; Martínez, C.A simple analytical model is proposed to describe the transversal spatial structure of a tridimensional rotationally symmetric pulsed beam. The spatial behaviour of the pulse amplitude is shown to be linked to its (measurable) second- and higher-order intensity moments, namely, beam width, quality parameter and kurtosis. As an illustrative experimental example, this model has been applied to high-quality TEA CO_2 laser pulses
- PublicationBeam quality changes produced by quartic phase transmittances(Kluwer Academic Publishers, 1995-03) Piquero Sanz, Gemma María; Martínez Herrero, Rosario; Mejías Arias, Pedro MiguelThe effects that quartic phase distortions generate in tridimensional beam quality parameters of laser fields are investigated. Two cases of special interest are considered: a rationally symmetric spherically aberrated lens, and a pair of identical but orthogonal cylindrical spherically aberrated lenses in contact with one another. Analytical expressions for the quality parameters at the output plane of these quartic-phase optical systems are derived. A number of conditions enabling determination in a definite way whether the quality improves or deteriorates are given for several significant kinds of fields. In particular, some general conclusions are found for perfect Gaussian beams that discriminate whether the two-lens system provides better output beam quality than the single-lens system.
- PublicationParametric characterization of Hermite-Gauss mode beams and Gauss Schell-model fields propagating through super-Gaussian apertures(Chapman & Hall Ltd., 1996-08) Serna Galán, Julio; Piquero Sanz, Gemma María; Mejías Arias, Pedro Miguel; Martínez Herrero, RosarioThe influence of super-Gaussian apertures on the beam power, beam size, beam quality factor and kurtosis parameter of Hermite-Gauss mode beams and Gauss Schell-model fields is investigated in detail.
- PublicationBeam quality changes of radially and azimuthally polarized fields propagating through quartic phase plates(Elsevier Science BV, 2008-02-15) Piquero Sanz, Gemma María; Martínez Herrero, Rosario; Mejías Arias, Pedro MiguelIn terms of the so-called irradiance moments of a light field, the beam quality change, ΔQ, of radially and azimuthally polarized beams caused by propagation through a quartic phase plate (as occurs for example, in strongly pumped laser rods used in high-power solid-state lasers) is studied. Analytical expressions for ΔQ are given, and a comparison between the scalar and vectorial regimes is also shown. The results are applied to several cases of interest.