Current Issue : April - June Volume : 2017 Issue Number : 2 Articles : 6 Articles
This paper describes an intrinsic Fabry-Perot interferometer (IFPI) temperature sensor with self-strain-compensation function.The\nsensor was fabricated on a buffer-intact optical fiber using a femtosecond (fs) laser system.The use of fs laser allows the sensor to be\nfabricated in an optical fiber without the necessity of removing the polymer buffer coating, thus not compromising its mechanical\nproperty.The sensor is composed of two cascaded IFPIs in different cavity length of 100 ...
Fused coupler forming with a single-mode fiber (SMF) and a photonic crystal fiber (PCF) is one of the solutions for optical coupling\nfrom a light source to a PCF. In this paper, we presented coupling characteristics of a fused fiber coupler formed with an ordinary\nSMF and a PCF having air hole collapsed taper. A prototype of SMF-PCF coupler with air hole collapsed taper was fabricated\nusing CO2 laser irradiation.The coupling efficiency from SMF to PCF was âË?â??6.2 dB at 1554nm wavelength in the fabricated coupler.\nThe structure of the SMF-PCF coupler to obtain high coupling efficiency was theoretically clarified by beam propagation analysis\nusing an equivalentmodel of the coupler with simplification. It was clarified that appropriately choosing the prestretched or etched\nSMF diameter and the length of air hole collapsed region was effective to obtain high coupling efficiency that was a result of high\nextinction ratio at cross port and low excess loss. We also demonstrated that the diameter of prestretched SMF to obtain high\ncoupling efficiency was insensitive to the air hole diameter ratio to pitch of the PCF in the air hole collapsed SMF-PCF coupler....
Optical frequency combs (OFC) generated by electro-optic modulation of continuous-wave\nlasers provide broadband coherent sources with high power per line and independent control of line\nspacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and\noptimized sources for the interrogation of other sensors based on wavelength change or wavelength\nfiltering, such as fiber Bragg grating (FBG) sensors. In this paper, a dual-OFC FBG interrogation\nsystem based on a single laser and two optical-phase modulators is presented. This architecture\nallows for the configuration of multimode optical source parameters such as the number of modes\nand their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping\nthe optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation\nscheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are\npresented for dual-comb operation under optimized control. The optical modes are mapped onto\ndetectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz).\nMeasurements of ultrasounds (40 kHz and 120 kHz) are demonstrated with this sensing system.\nUltrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg\nwavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum.\nThe amplitude modulation of two counterphase tones is detected to obtain a differential measurement\nproportional to the ultrasound signal....
A curved D-type optical fiber sensor (OFS) combined with a microfluidic chip is proposed.\nThis OFS, based on surface plasmon resonance (SPR) of the Kretchmannââ?¬â?¢s configuration, is applied\nas a biosensor to measure the concentrations of different bio-liquids such as ethanol, methanol, and\nglucose solutions. The SPR phenomenon is attained by using the optical fiber to guide the light source\nto reach the side-polished, gold-coated region. Integrating this OFS with a polymethylmethacrylate\n(PMMA)-based microfluidic chip, the SPR spectra for liquids with different refractive indices are\nrecorded. Experimentally, the sensitivity of the current biosensor was calculated to be in the order of\n10âË?â??5 RIU. This microfluidic chip-integrated OFS could be valuable for monitoring subtle changes in\nbiological samples such as blood sugar, allergen, and biomolecular interactions....
In this paper, the principle of distributed optical fiber measurement and measurement of axial stress is\nintroduced by analyzing the principle of Brillouin scattering in an optical fiber with a certain power. Making the\nexperimental device, measuring the individual strain model, analyzing the wave shape of the scattered wave, and\npreliminary understanding of the image characteristics of the stress in the optical fiber Brillouin scattering spectrum.\nThe effect of stress on the different position of the fiber, and the difference between them and the scattering waveform\nobtained from the stress free action poetry are compared, and the effect of the light pulse on the optical fiber\ntransmission is studied. The results show that the effect of the stress is different in the position of the action, and the\neffect of the propagation of the pulse light is mainly affected by the Stokes and anti Stokes light scattering. The\nresearch can provide reference for distributed optical fiber measurement, and it can promote the application of\ndistributed optical fiber in measuring micro deformation. The innovative point of this study is to use the pulley\nmethod to solve the effect of the different position of the same stress in the distribution of optical fiber....
Bell tests with entangled light have been performed many times in many ways using\nlinear polarizers, but the same tests have never been done with a circular polarizer.\nUntil recently there has never been a true circular polarization beam splitterââ?¬â?an\noptical component that separates light directly into left and right handed polarizations.\nUsing a true circular polarization beam splitter based on birefringent gratings,\nentangled light has been analyzed with unexpected results....
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