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A novel photonic crystal fiber with a Ge nanoparticles-doped germano-silicate core was fabricated by using the MCVD and stack-and-draw processes. Effect of Ge nanoparticles and the air-holes structure on non-resonant optical nonlinearity and supercontinuum generation was investigated.
In this article, an Adiabatic Tapered Optical Fiber — Fabry Perot (ATOF-FP) Sensor is introduced as a simple refractive index sensor. This FP Cavity relies upon reflection from two cleave ends of ATOF sensor's arms. Its spectrum was investigated with Distributed Feedback (DFB) tunable laser and photo detector. With analyzing the change in Optical Transmission Power (OTP) versus refractive index changes,...
This work shows the possibility of using chirped pulse amplification concepts in order to increase the signal-to-noise ratio (SNR) of phase sensitive optical time domain reflectometry (ΦOTDR) sensors. This method allows to increase the SNR of a ΦOTDR sensor without sacrificing spatial resolution. Here, we report a ΦOTDR sensor with a spatial resolution of 3 mm (limited only by the available detection...
This paper demonstrates the interrogation of a fiber Bragg grating with a flat-topped reflection spectrum centred on 1649.55 nm using only a single mode tunable 1651.93 nm semiconductor laser and a fiber ring resonator. The Bragg shift is accurately measured with the fiber-optic ring resonator that has a free spectral range (FSR) of 0.1008 GHz and a broadband photo-detector. Laser wavelength modulation...
Effect of fluorine (F) doping in the core of a birefringent photonic crystal fiber (PCF) on sensing capability of temperature and strain was investigated by using Sagnac loop interferometry. The birefringence of the F-doped PCF was measured to be 1.56χ10−4 at 1550 nm and the temperature and the strain sensitivities of the F-doped PCF were found to increase from −9.6 pm/°C/m to −34 pm/°C/m and from...
Low thermal sensitivity and cross sensitivity of Fiber Bragg Grating (FBG) towards the applied strain, temperature make FBG implementation complicated in composite materials at cryogenic conditions. In order to alleviate this problem, our work focuses on simultaneous strain and temperature monitoring inside the composite material at cryogenic temperatures. The temperature sensitive polymer coating...
We present a terahertz (THz) radiation pumped by a passively mode-locked Yb-doped fiber laser using two fiber-pigtailed log-spiral-based low-temperature-grown (LTG) InGaAs photoconductive antenna (PCA) modules. The mode-locked fiber laser produces over 220 mW of the average optical power with positively chirped of 1.49 ps pulses. In order to generate THz radiation using the fiber-pigtailed PCA modules,...
We demonstrate a high spatial resolution multiplexing scheme for fiber Bragg grating (FBG) sensors based on single-arm frequency-shifted interferometry (SA-FSI). The SA-FSI system uses an incoherent broadband source, a slow detector, and an electro-optic modulator (EOM). By sweeping the frequency of EOM and taking the fast Fourier transform (FFT) of the interference signal, we resolved the locations...
In this paper, an impact monitoring system using fiber Bragg grating (FBG) sensors and vibro-haptic actuators have been introduced. The system is suggested for structural health monitoring (SHM) for unmmaned aerial vehicles (UAVs), by making a decision with human-robot interaction. The system is composed with two major subsystems; an on-board system equipped on UAV and an arm-wearable interface for...
In this paper, we present a tilted fiber Bragg gratings (TFBG) based surface Plasmon resonance (SPR) labelfree sensors with boronic acid derivative (ABA-PBA) as receptor molecule to detect glycoprotein with high sensitivity and selectivity. Tilted fiber Bragg gratings (TFBG) as a near infrared wavelengths detecting element can be able to excite a number of cladding modes whose properties can be detected...
In this paper the behaviour of fibre Bragg grating (FBG) sensors under non-uniform strain distributions was analysed. Using the fundamental matrix approach, the length of the FBG sensor was discretised, with each segment undergoing different strain values. FBG sensors that are embedded inside composites, also undergo such non-uniform strain distributions, when located in the vicinity of failures such...
A novel broadband light source based on supercontinuum (SC) generation seeded by random distributed feedback fiber laser (RFL) is proposed and demonstrated for the first time. A half-opened fiber cavity formed by FBG and TrueWave fiber is used to generate random lasing and SC simultaneously. Experimental results indicate that RFL can be used as an effective pump for generation of SC. SC with 20-dB...
Herein, we present a study of the use of polymer capillary optical fibers in sensing measurements. In particular, we approach the application of these fibers for temperature sensing. To do this, an analytical model for describing the spectral characteristics of the light transmitted through the capillaries was employed. Thermal expansion and thermo-optic effect influences on the transmitted spectrum...
A compact refractive index (RI) sensing probe with controllable sensitivities based on a θ-shaped microfiber resonator and Vernier effect is reported. By cascading the θ-shaped microfiber resonator with a fiber Fabry-Perot interferometer, Vernier effect is generated to enhance the RI sensitivity. Both theoretical analyses and experimental results demonstrate that the RI sensitivity can be tuned by...
A novel distributed fiber-optic vibration sensor (DVS) is proposed based on multi-pulse time-gated digital optical frequency domain reflectometry (TGD-OFDR), which can solve both the trade-off between the maximum measurable distance and the spatial resolution, and the one between the measurement distance and the vibration response bandwidth. A 21-kHz vibration is detected experimentally over 10-kilometer-long...
In this paper, a new multipoint optical fiber system for relative humidity measurements based on SnO2-FP (Fabry-Pérot) sensing heads and an optical interrogator as single active device is presented and characterized. The interrogation of the sensing heads is carried out by monitoring the Fast Fourier Transform phase variations of the FP (Fabry-Pérot) interference frequencies. This method allows to...
Brillouin scattering properties of a bend-insensitive fiber were experimentally investigated at 850 nm and 1550 nm wavelength using Brillouin optical time-domain analysis (BOTDA). A diversity scheme has been adopted, in which the BFS distribution along the same fiber is acquired at the two operating wavelengths. Based on the different wavelength scaling factor of temperature and strain coefficients,...
We present a white light base method for measuring the distributed birefringence dispersion (BD) of polarization-maintaining using optimization algorithm. An optimization function of an interferogram is proposed and we proved that it will reach its maximum when we found the real BD of the interferogram. It is demonstrated that this method is robust to noise via simulation. The measured average distributed...
High-speed railway is being developed rapidly; its safety, including infrastructure and train operation, is vital. This paper presents a railway-subgrade vibration monitoring scheme based on phase-sensitive OTDR for railway safety. The subgrade vibration is detected and rebuilt. Multi-dimension comprehensive analysis (MDCA) is proposed to identify the running train signals and illegal constructions...
The temperature properties of bismuth active centers (BACs) on Bismuth/Erbium co-Doped Optical Fibers (BEDFs) have been demonstrated and the reasons of this phenomenon are explained. The possibility of temperature sensor based BEDFs has also been discussed.
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