Design of hollow core step-index antiresonant fiber with stepped refractive indices cladding

With the benefits of low latency,wide transmission bandwidth,and large mode field area,hollow-core antiresonant fiber(HC-ARF)has been a research hotspot in the past decade.In this paper,a hollow core step-index antiresonant fiber(HC-SARF),with stepped refractive indices cladding,is proposed and numerically demonstrated with the benefits of loss reduction and bending improvement.Glass-based capil-laries with both high(n=1.45)and low(as low as n=1.36)refractive indices layers are introduced and formatted in the cladding air holes.Using the finite element method to perform numerical analysis of the designed fiber,results show that at the laser wavelengths of 980 and 1064 nm,the confinement loss is favorably reduced by about 6 dB/km compared with the conventional uniform cladding HC-ARF.The bending loss,around 15 cm bending radius of this fiber,is also reduced by 2 dB/km.The cladding air hole radius in this fiber is further investigated to optimize the confinement loss and the mode field diameter with single-mode transmission behavior.This proposed HC-SARF has great potential in optical fiber transmission and high energy delivery.

AMORPHOUS POLY(ETHYLENE TEREPHTHALATE) FILMS IN THE STATE OF HIGH GLOBAL CHAIN ORIENTATION BUT NEARLY RANDOM SEGMENTAL ORIENTATION

The isotropy or anisotropy in some physical properties of the amorphous poly(ethylene terephthalate) films uniaxially drawn at temperatures above its T-g and then quenched to room temperature have been studied. Experimental results here presented show that this amorphous state of high global chain orientation but nearly random segmental orientation, the GOLR state, is nearly isotropic in refractive indices and Young's modulus for small deformation, while it is very probably anisotropic in thermal conduction and microwave dielectric properties.

Role of refractive index in sum frequency generation intensity of salt solution interfaces

Sum frequency generation spectroscopy（SFG） has been widely used to study the interfacial chemistry of aqueous salt solutions of biological or environmental importance. Most of the SFG data analysis used the same bulk refractive index for different salt concentrations despite of the variations of the refractive indices. Here we systematically investigate the influence of the refractive index on the SFG intensities at various experimental conditions. It is discovered that the SFG intensities are the most sensitive to the refractive index at solid/liquid interfaces nearby the total internal reflection geometries. At air/liquid interfaces, the effect of the refractive indices is also nonegligible. Consequently some important SFG results, such as the response of water structures to the ionic strength at the SiO2/aqueous interfaces, are necessary to be reevaluated. These conclusions on the effect of the small variations of the refractive index are generally useful for the common practice of SFG data analysis.

Equilibrium Phase Behavior of Ethylene Glycol/Glycerin＋RbNO3/CsNO3＋H2O at 288.15 and 298.15 K

The solubilities, densities and refractive indices for the four ternary systems ethylene glycol/glycerin＋ RbNOJCsNO3＋H20 were measured with mass fractions of ethylene glycol or glycerin in a range of 0 to 1.0 at 288.15 and 298.15 K. In all the cases, the presence of either ethylene glycol or glycerin significantly reduces the solubilities of the rubidium nitrate and cesium nitrate in aqueous solution, but the refractive indices increase with the increase of mass fraction of either ethylene glycol or glycerin. The density, refractive index and solubility of the saturated ternary systems were correlated with each other via polynomial equations. In addition, the refractive indices and densities of unsaturated solutions were also determined for the four ternary systems with different salt concentrations, which were correlated with the salt concentration and proportion of ethylene glycol or glycerin in the solution.

Self-calibrated global rainbow refractometry:a dual-wavelength approach

Calibration of the relationship between the scattering angle and the CCD pixel is a key part of achieving accurate measurements of rainbow refractometry.A novel self-calibrated global rainbow refractometry system based on illumination by two lasers of different wavelengths is proposed.The angular calibration and refractive index measurement of two wavelengths can be completed simultaneously without extra measurement devices.The numerical and experimental results show the feasibility and high precision of the self-calibration method,which enables the rainbow refractometry to be implemented in a more powerful and convenient way.The self-calibrated rainbow system is successfully applied to measure the refractive indices of ethanol-water solutions with volume concentrations of 10% to 60%.