Metamaterial dielectric resonators represent a promising path toward low-loss metamaterials at optical frequencies. In this paper we utilize perturbations of high symmetry resonator geometries, such ...as cubes, either to overlap the electric and magnetic dipole resonances, thereby enabling directional scattering and Huygens' metasurfaces, or to induce couplings between the otherwise orthogonal resonator modes to achieve high-quality factor Fano resonances. Our results are fully scalable across any frequency bands where high-permittivity dielectric materials are available, including microwave, THz and infrared frequencies.
We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality-factor Fano resonances. Our approach utilizes symmetry ...breaking of highly symmetric resonator geoemetries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple "bright" dipole modes to "dark" dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurface that achieved a quality-factor of ~1300 at ~10.8 um. Then, we present two experimental demonstrations operating in the near-infrared (~1 um): a silicon-based implementation that achieved a quality-factor of ~350; and a gallium arsenide-based structure that achieves a quality-factor of ~600 - the highest near-infrared quality-factor experimentally demonstrated to date with this kind of metasurfaces. Importantly, large electromagnetic field enhancements appear within the resonators at the Fano resonant frequencies. We envision that combining high-quality factor, high field enhancement resonances with nonlinear and active/gain materials such as gallium arsenide will lead to new classes of active optical devices.
We demonstrate, for the first time, an all-dielectric metamaterial resonator in the mid-wave infrared based on high-index tellurium cubic inclusions. Dielectric resonators are desirable compared to ...conventional metallo-dielectric metamaterials at optical frequencies as they are largely angular invariant, free of ohmic loss, and easily integrated into three-dimensional volumes. With these low-loss, isotropic elements, disruptive optical metamaterial designs, such as wide-angle lenses and cloaks, can be more easily realized.
In a cooperative study at 13 centres in the Federal Republic of Germany, 213 adult patients with AML were treated for remission induction by a 9-day regimen consisting of cytosine arabinoside, ...daunorubicin and thioguanine (TAD) according to previously described sequencing. Complete remission was achieved in 70% of all patients. Complete remission rate was 57% in the 49 patients 60 years of age and older and 74% in the 164 patients under 60 years. Sixty-eight per cent of all complete remissions and 75% of those in the higher age group were induced by one induction course. Median survival was 10 months for all patients treated and 16 months for responders. Median remission duration was 13 months with 72 patients still in continuous remission for 1-31 months. Remission duration was not significantly different for patients treated either by monthly maintenance therapy or induction type consolidation without further therapy. However, patients completing two consolidation courses had a significantly longer remission duration of 22 months. Compared to similar multicentre studies on AML therapy the intensified induction regimen applied in this study shows an improvement even in older patients.
PDF
