Dynamics of grating formation in photovoltaic media

The Kukhtarev equations are solved taking into account the photovoltaic effect and different boundary conditions. In the case of open circuit, the voltage across the crystal is found to vary with a time scale similar to the photorefractive time constant. This effect explains the dynamic behavior observed experimentally

Di-μ-benzoato-κ3 O,O′:O′;κ3 O:O,O′-bis­[(benzoato-κ2 O,O′)(1,10-phenanthroline-κ2 N,N′)cadmium]

The dinuclear title compound, [Cd2(C7H5O2)4(C12H8N2)2], lies on a crystallographic twofold axis. The CdII ions are connected by two bridging benzoate anions and each ion is seven-coordinated by five O atoms from three benzoate ligands and by two N atoms from 1,10-phenanthroline. The benzoate ligands adopt two different coordination modes, acting as bidentate and bridging tridentate ligands. The discrete neutral mol­ecules further extend their structure into a three-dimensional supra­molecular framework by inter­molecular π–π [inter­planar distances of 3.392 (4) Å] and C—H⋯π stacking inter­actions [H–mean plane = 2.567 (4) and 2.781 (4) Å]

Cancer-cell microsurgery using nonlinear optical endomicroscopy

Near-infrared laser-based microsurgery is promising for noninvasive cancer treatment. To make it a safe technique, a therapeutic process should be controllable and energy efficient, which requires the cancer cells to be identifiable and observable. In this work, for the first time we use a miniaturized nonlinear optical endomicroscope to achieve microtreatment of cancer cells labeled with gold nanorods. Due to the high two-photon-excited photoluminescence of gold nanorods, HeLa cells inside a tissue phantom up to 250 &mu;m deep can be imaged by the nonlinear optical endomicroscope. This facilitates microsurgery of selected cancer cells by inducing instant damage through the necrosis process, or by stopping cell proliferation through the apoptosis process. The results indicate that a combination of nonlinear endomicroscopy with gold nanoparticles is potentially viable for minimally invasive cancer treatment.<br /

Mode Interferences of VLF Waves in the Presence of an Anisotropic Terrestrial Waveguide

It is known that the very low frequency (VLF) signals propagating at long distances over a terrestrial waveguide will experience a diurnal interference across the sunrise and sunset transitions. Early studies indicated that cascaded terrestrial waveguides can be applied to investigate the cycle-clip behaviors of amplitude and phase for VLF waves, with an abrupt effective height change by 20 km to represent the night and day transitions. Based on the knowledge, this chapter starts with some basic concepts on VLF wave propagation in the presence of an anisotropic terrestrial waveguide. Then, by performing the method of field matching at the discontinuous junctions, the coefficients of transmitted and scattered vectors are resulted from two derived matrix equations. Finally, the synthetic fields are calculated to simulate the VLF waves, which are subjected to an oblique geomagnetic field during long-distance propagation. The purpose of the present chapter is to illustrate the disturbing nature during sunrise and sunset for the VLF waves with periodic variations in amplitudes interfered by multimodes over long propagation paths

Improvement of two-way continuous-variable quantum key distribution using optical amplifiers

The imperfections of a receiver's detector affect the performance of two-way continuous-variable quantum key distribution protocols and are difficult to adjust in practical situations. We propose a method to improve the performance of two-way continuous-variable quantum key distribution by adding a parameter-adjustable optical amplifier at the receiver. A security analysis is derived against a two-mode collective entangling cloner attack. Our simulations show that the proposed method can improve the performance of protocols as long as the inherent noise of the amplifier is lower than a critical value, defined as the tolerable amplifier noise. Furthermore, the optimal performance can approach the scenario where a perfect detector is used.Comment: 14 pages, 7 figure

Enhanced photothermal therapy assisted with gold nanorods using a radially polarized beam

We report on the use of a radially polarized beam for photothermal therapy of cancer cells labeled with gold nanorods. Due to a three-dimensionally distributed electromagnetic field in the focal volume, the radially polarized beam is proven to be a highly efficient laser mode to excite gold nanorods randomly oriented in cancer cells. As a result, the energy fluence for effective cancer cell damage is reduced to one fifth of that required for a linearly polarized beam, which is only 9.3% of the medical safety level.<br /