The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform

Kwangjoon Kim - One of the best experts on this subject based on the ideXlab platform.

Wol-yon Hwang - One of the best experts on this subject based on the ideXlab platform.

Jennifer W. Graham - One of the best experts on this subject based on the ideXlab platform.

  • Field distributions of the hybrid modes in rectangular waveguides filled with uniaxial media with tilted Optic Axis lying in sidewall planes
    2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2017
    Co-Authors: Jennifer W. Graham
    Abstract:

    The field distributions of various modes in rectangular waveguides filled with uniaxial media are presented. The presented cases include aligned cases when the Optic Axis is parallel to one of the coordinate axes and the tilted cases when the Optic Axis is not parallel to any of the coordinate axes but still lies within one of the two side-wall planes. In the aligned uniaxial-z case the analytical solution is compared with the results of the dyadic green's functions (DGF). In other aligned cases the field distributions of selected extra-ordinary wave modes are also plotted and to be compared with the isotropic case. In the tilted cases, the field distributions of the hybrid modes which are coupled ordinary-waves and extra-ordinary waves show asymmetry which is not seen in the aligned cases and isotropic case. The validity of the hybrid mode field plots are verified by comparing a limiting tilted case with analytical solutions of an aligned case.

  • Fields and Wave Modes Analysis of Rectangular Waveguide Filled With Uniaxial Medium
    IEEE Transactions on Microwave Theory and Techniques, 2016
    Co-Authors: Kepei Sun, Jay Kyoon Lee, Jennifer W. Graham
    Abstract:

    A rectangular waveguide filled with a uniaxial medium is treated. Different orientations of the Optic Axis are considered, and the transmission characteristics of the guided waves are studied. When the Optic Axis is parallel to one of the $x$ -, $y$ -, and $z$ -axes, results of wave decompositions with respect to the Optic Axis are presented and compared with conventional transverse-to-z solutions. Computation shows that the anisotropy not only changes the field distributions, but also leads to changes in the dominant modes in the waveguide. When the Optic Axis is tilted but lying in one of the sidewall planes, $\mathrm {TE}_{0n}$ or $\mathrm {TE}_{m0}$ (to $z$ ) modes are shown to exist, and supported hybrid wave modes are found from calculations using the proposed boundary condition matrix method. The hybrid wave is expressed as a linear combination of ordinary and extraordinary waves. The algorithm developed to address this problem is illustrated and numerical examples are given. The validity of the solution is verified by comparing its results with those of the aligned cases that are analytically solved.

  • Rectangular waveguide containing uniaxial medium with tilted Optic Axis in sidewall plane
    2015 IEEE International Symposium on Antennas and Propagation & USNC URSI National Radio Science Meeting, 2015
    Co-Authors: Kepei Sun, Jay Kyoon Lee, Jennifer W. Graham
    Abstract:

    Solutions of a metallic rectangular waveguide filled with uniaxial medium are obtained with a new approach. The direction of the Optic Axis is tilted but lying in one of the sidewall planes of the waveguide. The formulation is based on decomposition into ordinary and extraordinary waves. The proposed method seeks wavenumbers of supported travelling modes, and is also able to calculate both cutoff frequencies and field magnitudes of every mode supported.

  • Analysis of rectangular waveguide containing uniaxial medium with aligned Optic Axis
    2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
    Co-Authors: Kepei Sun, Jay Kyoon Lee, Jennifer W. Graham
    Abstract:

    A rectangular waveguide filled with uniaxial medium is treated. Different orientations of the Optic Axis are considered. Results of wave decompositions with respect to the Optic Axis are presented and compared with conventional transverse-to-z solutions. Computations show that the effect of anisotropy not only changes the field distributions, but also leads to changes of dominant modes in the waveguide.

Marc Eichhorn - One of the best experts on this subject based on the ideXlab platform.

  • Orientation and polarization dependence of both the absorption and the laser efficiency around the Optic Axis in monoclinic $$\hbox {Ho}^{3+}$$
    Applied Physics B, 2015
    Co-Authors: Romain Cattoor, Inka Manek-hönninger, Daniel Rytz, Lionel Canioni, Yannick Petit, Marc Eichhorn
    Abstract:

    We report on the absorption profile of the monoclinic holmium-doped $$\hbox {KY}(\hbox {WO}_4)_2$$ KY ( WO 4 ) 2 crystal near the Optic Axis for the maximal absorption wavelength at 1960 nm. The full angular distribution of the absorption coefficient at the vicinity of such Optical singularity has been experimentally and numerically investigated. Furthermore, laser experiments along the Optic Axis have been carried out. So-called conical refraction laser and classical Gaussian laser operation are compared near the Optic Axis, taking into account the complex absorption profile.

  • Laser action along and near the Optic Axis of a holmium-doped KY(WO 4 ) 2 crystal
    Optics Letters, 2014
    Co-Authors: Romain Cattoor, Inka Manek-hönninger, Daniel Rytz, Lionel Canioni, Marc Eichhorn
    Abstract:

    We demonstrate the first (to our knowledge) quasi-three-level conical refraction laser operating at 2 μm, with 1.6 W of output power at 2074 nm, using a holmium-doped KY…WO 4 † 2 crystal. A maximum slope efficiency of 52% has been achieved, along the Optic Axis with respect to the absorbed pump power. Furthermore, lasing operation around the Optic Axis has been performed. In this case, a maximum output power of 3 W has been reached, with a slope efficiency better than 70%, which are the best performances ever reported on this material. Studies of conical refraction (CR) have recently revived. When a Gaussian light beam propagates along the Optic Axis of a biaxial crystal, under certain conditions a two ring-shaped beam can be observed, at the exit face of the crystal. Several publications describe this effect, theo-retically and experimentally [1–4]. Recent availability of long biaxial crystals, with good Optical quality, facili-tates CR studies. Therefore, several applications of this effect have recently been investigated, such as Optical tweezers [5], particle trapping [6], beam shaping [7–11], and microscopy [12]. There are also some publications about laser operation along an Optic Axis of a biaxial crys-tal, the first publication being [13]. Using a short (3 mm long) biaxial crystal of a CR-cut ytterbium-doped KGd…WO 4 † 2 (KGW), the output polarization of their laser was modified, by translating the output coupler mirror. The researchers obtained a slope efficiency of 60% along the CR Axis, which is similar to the value obtained for a classical N g -cut orientation. However, the threshold was 2× higher for CR orientation. A few years later, [14,15] presented a four-level conical refraction laser, made with neodymium-doped KGW. The researchers obtained both a Gaussian and CR output beam. They reported a slope efficiency close to the quantum defect limit [14], and no influence of any thermal effect over the measurement range (up to 3 W at 1067 nm) was observed. The thermo-Optic properties of neodymium-doped KGW were studied in [16]. The researchers show the anisotropy of the thermo-Optic properties, along this propagation direc-tion with a short crystal (1 mm long). However, the effect of CR inside the cavity, changing the light distribution in-side the crystal, is still not well-known. In this Letter, we report the first experimental results (to our knowledge) of a holmium-doped KY…WO 4 † 2 (KYW) CR laser, showing laser action along the CR Axis. Measurements near the Optic Axis have also been per-formed, in order to be able to compare CR and Gaussian beam intracavity laser performance.

  • Laser action along and near the Optic Axis of a holmium-doped KY(WO 4 ) 2 crystal
    Optics letters, 2014
    Co-Authors: Romain Cattoor, Inka Manek-hönninger, Daniel Rytz, Lionel Canioni, Marc Eichhorn
    Abstract:

    We demonstrate the first (to our knowledge) quasi-three-level conical refraction laser operating at 2 μm, with 1.6 W of output power at 2074 nm, using a holmium-doped KY(WO4)2 crystal. A maximum slope efficiency of 52% has been achieved, along the Optic Axis with respect to the absorbed pump power. Furthermore, lasing operation around the Optic Axis has been performed. In this case, a maximum output power of 3 W has been reached, with a slope efficiency better than 70%, which are the best performances ever reported on this material.

  • Optic Axis dispersion in double tungstate crystals and laser operation at 2 μm
    Solid State Lasers XXIII: Technology and Devices, 2014
    Co-Authors: Romain Cattoor, Inka Manek-hönninger, Daniel Rytz, Lionel Canioni, Marc Tondusson, Philippe Veber, Todor K. Kalkandjiev, Marc Eichhorn
    Abstract:

    Measurements of the Optic Axis dispersion in double tungstate crystals have been performed from 400 nm to 1.58 μm. The measurements have been performed on KGdW, Nd-doped KGdW and Ho-doped KYW crystals. The samples were longer than 1 cm and had a good Optical quality. The absolute angle reference was set using the Laue method. This reference allows us to compare more accurately our measurements with the calculations made using refractive index values found in literature. The difference observed between calculated values and measurements is significant. The relative dispersion looks similar for all double tungstate crystals tested. Furthermore first results of Holmium doped KYW laser operation along this Axis will be shown.

Kepei Sun - One of the best experts on this subject based on the ideXlab platform.

  • Hybrid mode analysis of rectangular waveguide filled with uniaxial media with tilted Optic Axis lying in sidewall planes
    2016 IEEE Conference on Antenna Measurements & Applications (CAMA), 2016
    Co-Authors: Kepei Sun, Jay Kyoon Lee
    Abstract:

    Computational results of the cutoff frequencies of the hybrid modes in a rectangular waveguide filled with the uniaxial medium are presented. The Optic Axis orientation of the inserted uniaxial medium is tilted from any of the coordinate axes but lying in one of the sidewall planes of the rectangular waveguide. The calculated results not only show the changes of the cutoff frequency of the lowest hybrid mode as the constitutive parameters and the waveguide dimensions change, but also justify the correctness of the computational process and the formulations.

  • Fields and Wave Modes Analysis of Rectangular Waveguide Filled With Uniaxial Medium
    IEEE Transactions on Microwave Theory and Techniques, 2016
    Co-Authors: Kepei Sun, Jay Kyoon Lee, Jennifer W. Graham
    Abstract:

    A rectangular waveguide filled with a uniaxial medium is treated. Different orientations of the Optic Axis are considered, and the transmission characteristics of the guided waves are studied. When the Optic Axis is parallel to one of the $x$ -, $y$ -, and $z$ -axes, results of wave decompositions with respect to the Optic Axis are presented and compared with conventional transverse-to-z solutions. Computation shows that the anisotropy not only changes the field distributions, but also leads to changes in the dominant modes in the waveguide. When the Optic Axis is tilted but lying in one of the sidewall planes, $\mathrm {TE}_{0n}$ or $\mathrm {TE}_{m0}$ (to $z$ ) modes are shown to exist, and supported hybrid wave modes are found from calculations using the proposed boundary condition matrix method. The hybrid wave is expressed as a linear combination of ordinary and extraordinary waves. The algorithm developed to address this problem is illustrated and numerical examples are given. The validity of the solution is verified by comparing its results with those of the aligned cases that are analytically solved.

  • Rectangular waveguide containing uniaxial medium with tilted Optic Axis in sidewall plane
    2015 IEEE International Symposium on Antennas and Propagation & USNC URSI National Radio Science Meeting, 2015
    Co-Authors: Kepei Sun, Jay Kyoon Lee, Jennifer W. Graham
    Abstract:

    Solutions of a metallic rectangular waveguide filled with uniaxial medium are obtained with a new approach. The direction of the Optic Axis is tilted but lying in one of the sidewall planes of the waveguide. The formulation is based on decomposition into ordinary and extraordinary waves. The proposed method seeks wavenumbers of supported travelling modes, and is also able to calculate both cutoff frequencies and field magnitudes of every mode supported.

  • Analysis of rectangular waveguide containing uniaxial medium with aligned Optic Axis
    2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
    Co-Authors: Kepei Sun, Jay Kyoon Lee, Jennifer W. Graham
    Abstract:

    A rectangular waveguide filled with uniaxial medium is treated. Different orientations of the Optic Axis are considered. Results of wave decompositions with respect to the Optic Axis are presented and compared with conventional transverse-to-z solutions. Computations show that the effect of anisotropy not only changes the field distributions, but also leads to changes of dominant modes in the waveguide.