Efficient excitations of radially and azimuthally polarized Nd3+:YAG ceramic microchip laser by use of subwavelength multilayer concentric gratings composed of Nb2O5/SiO2.

Institute for Laser Science, University of Electro-Communications, Tokyo 182-8585, Japan.
Optics Express (Impact Factor: 3.53). 08/2008; 16(14):10841-8. DOI: 10.1364/OE.16.010841
Source: PubMed

ABSTRACT Cylindrical vector beams were produced from laser diode end-pumped Nd:YAG ceramic microchip laser by use of two types of subwavelength multilayer gratings as the axisymmetric-polarization output couplers respectively. The grating mirrors are composed of high- and low-refractive- index (Nb(2)O(5)/SiO(2)) layers alternately while each layer is shaped into triangle and concentric corrugations. For radially polarized laser output, the beam power reached 610mW with a polarization extinction ratio (PER) of 61:1 and a slope efficiency of 68.2%; for azimuthally polarized laser output, the beam power reached 626mW with a PER of 58:1 and a slope efficiency of 47.6%. In both cases, the laser beams had near-diffraction limited quality. Small differences of beam power, PER and slope efficiency between radially and azimuthally polarized laser outputs were not critical, and could be minimized by further optimized adjustment to laser cavity and the reflectances of respective grating mirrors. The results manifested, by use of the photonic crystal gratings mirrors and end-pumped microchip laser configuration, CVBs can be generated efficiently with high modal symmetry and polarization purity.


Available from: Ken-ichi Ueda, Jun 17, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Exchange of orbital angular momentum between Laguerre-Gaussian beam of light and center-of-mass motion of an atom or molecule is well known. In this letter, we show that orbital angular momentum of light can also be transferred to the internal electronic or rotational motion of an atom or a molecule provided the internal and center-of-mass motions become coupled by light-atom or light-molecule interaction. However, this transfer does not happen directly to the internal motion, but via center-of-mass motion. If atoms or molecules are cooled down to recoil limit then an exchange of angular momentum between the quantized center-of-mass motion and the internal motion is possible during interaction of cold atoms or molecules with Laguerre-Gaussian beam. The orientation of the exchanged angular momentum is determined by the sign of the winding number of Laguerre-Gaussian beam.
    Physical Review A 03/2014; 89(6). DOI:10.1103/PhysRevA.89.063418 · 2.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A hybrid circular subwavelength grating mirror is proposed and fabricated as a rear mirror in a fast axial flow CO<sub>2</sub> laser system to generate azimuthally polarized beams (APBs). This grating mirror, with particular gold-covered ridges and nanopillar-stuffed grooves, performs wideband TE wave reflectivity and high polarization selectivity. It shows that the polarization selectivity mechanism lies in the gold ridge's high reflectivity to the TE wave and the lower TM wave reflectivity, which are the result of the mode leaking into substrate through the dielectric-like nanopillar layer. Finally, a high-quality 550 W APB is obtained in subsequent experiments, which provides potential applications in drilling and welding.
    Applied Optics 06/2014; 53(17):3706-3711. DOI:10.1364/AO.53.003706 · 1.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A study on Laguerre-Gaussian (LG) modes selection in cw and pulsed Nd:YAG or Yb:YAG ceramic lasers pumped by diodes or an external laser source was carried out. Methods of scalar and vector LG modes selection from low to high orders, involving shaping of the pump profile, usage of intra-cavity lenses, uniaxial crystals and polarization selective mirrors, are considered. CCD camera images of beam profiles of hollow scalar LG(pm) modes (p-radial, m-azimuth indices) of record high-orders and Bessel-like multi-ring modes with highly directional propagation properties are presented. CW and pulsed ceramic lasers with radially or azimuthally polarized LG vector modes of low and high orders are also demonstrated. Applications of the developed laser schemes and LG beams are discussed. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
    physica status solidi (c) 06/2013; 10(6):974–980. DOI:10.1002/pssc.201300022