A fiber optic relative humidity (RH) sensor based on the tilted Bragg grating (TFBG) coated with graphene oxide (GO) film was presented. Amplitudes of cladding mode resonances TFGB varies water sorption and desorption processes GO film, because strong interactions between excited backward propagating modes film. By detecting transmission intensity changes resonant dips at wavelength 1557 nm, maximum sensitivity 0.129 dB/%RH a linear correlation coefficient 99% under RH range 10–80% obtained....

Based on the vector angular spectrum representation and method of stationary phase, analytical vectorial structure cylindrically polarized Laguerre-Gaussian beam diffracted at a circular aperture is derived in far field, which provides an approach to further comprehend properties apertured beams. The radially polarized, azimuthally unapertured cases can be viewed as special our general result. analyses show that far-field energy flux distributions entire beam, TE term, TM term depend order,...

Recently, we had reported some fiber sensing applications by using the tilted Bragg grating (TFBG), such as twist sensor, polarization curve sensor and relative humidity so on. Here, summarized two kinds of TFBG-based sensors (humidity- twist-sensing) for conference ICOCN 2016. An optical based on a graphene oxide coated TFBG surface plasmon resonance (SPR) effect an Au-coated were presented. The sensitivity 0.129 dB/%RH with linear correlation coefficient 99% under RH range 10%~80% was...

The far-field analytical expressions for the electromagnetic fields of a cylindrically polarized vector beam propagating in free space are obtained based on angular spectrum and method stationary phase.The energy flux distributions quality by power bucket (PIB) nonparaxial regime have been investigated.The PIB depends ratio waist width to wavelength, order Laguerre polynomial, angle between electrical radial direction.The analyses show that azimuthal polarization compared with has better...

A ``plane cathode micro-hollow anode discharge (PCHAD)'' is studied in comparison with (MHCD). new triode-configuration device also designed for large-volume, high-pressure glow discharges plasma without glow-to-arc transitions, as well an metal needle, and a of PCHAD. It has ``needle-hole" sustained discharge. Its circuit employs only one power supply variable resistor. The experiments have been carried out the air. electrical properties photo-images PCHAD, multi-PCHAD investigated. optical...

The effect of initial frequency chirp input pulses on pulse dynamics and spectral broadening in all-normal dispersion photonic crystal fibers are investigated numerically. When the peak power is low, for small positive chirps can enhance bandwidth supercontinuum while negative compress spectrum. increases be further increased similar both signs chirp. Especially, simulations show that there exists an optimal value makes flattest almost without fine structures. For high have a little...

To increase the photoelectronic conversion efficiency of single discharge tube and to meet requirements laser cutting system, optimization structure gas flow field is necessary.We present a computational fluid dynamic model predict characteristics high-power fast-axial CO2 laser.A set differential equations used describe operation laser.Gas characteristics, are calculated.The effects velocity turbulence intensity on stability studied.Computational results compared with experimental values,...

A theoretical investigation on the parabolic pulse nonlinear propagation and spectral compression in all-normal dispersion photonic crystal fibers (PCFs) is presented. It found that use of larger chirp can obtain higher quality transform-limited spectrally compressed pulses due to almost purely effects self-phase modulation (SPM) — because its with smaller group velocity (GVD). Also, long initial negatively chirped lead most efficient under optimal condition.

Aiming to the special high power CO₂ laser surface treatment, paper developed integrated control system based on S7-200 PLC of transverse flow laser. The selection key technology and components, detection signals, complete circuit, human machine interface process have been researched. Double closed loop was realized, so that stability in ±2%. Also, giving can be controlled by controller or processing machine, thus, users more efficiently when processing. A series experiments...

A new kind of measure and control system for high power CO₂ lasers in real-time is designed order to improve stabilization accuracy power, includes tow parts, one the sample unit, made a rear mirror, an integrating sphere infrared detector, other feedback unit PID controller. This adjusts output makes laser stable required scope by closed-loop according signal, which depends on sampling transmitted out mirror resonator. can detect monitor line has no influence beam. It greatly...

In order to improve the injection power of laser and guarantee normal operation RF-excited Fast Axial Flow CO2 Laser, A kind neural network control technology is proposed in a 2MHz RF supply, which consists two single-phase half-bridge MOSFET inverter modules. By using SLPS Interface (SLPS), supply system with controller built simulated. The result shows that output from can be up 2000W, little distortion (THD 0.013%) obtained. Moreover, it suggests possesses better adaptivity than PI...

A simple and low cost transverse load fiber sensor based on in-line Mach-Zehnder interferometer (MZI) is proposed. The head formed by a single mode fiber-polarization maintaining fiber-single (SMF-PMF-SMF) structure through core-offset fusion splicing. With the increasing of PMF, couple efficiency between core cladding PMF decreased, which further brings about change interference fringe visibility. experimental results show that with 1.3 cm-long has sensitivities 12.85 dB/(N/mm) 30.69 for...