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Pulse delay via tunable white light cavities using fiber optic resonators  [PDF]
Honam Yum,Youngjoon Jang,May Kim,Xue Liu,Selim Shahriar
Physics , 2010, DOI: 10.1109/JLT.2011.2162090
Abstract: Previously, we proposed a data buffering system that makes use of a pair of white light cavities. For application to telecommunication systems, it would be convenient to realize such a device using fiber optic resonators. In this paper, we present the design of such a system, where the white light cavity effect is produced by using stimulated Brillouin scattering. The system consists of a pair of fiber optic white light cavities placed in series. As in the original proposal, the delay time can be controlled independently of the bandwidth of the data pulses. Furthermore, we show how the bandwidth of the system can be made as large as several times the Brillouin frequency shift. We also show that the net delay achievable in such a buffer can be significantly larger than what can be achieved using a conventional recirculating loop buffer.
Fiber-Optic Interferometry Using Narrowband Light Source and Electrical Spectrum Analyzer: Influence on Brillouin Measurement  [PDF]
Yosuke Mizuno,Neisei Hayashi,Kentaro Nakamura
Physics , 2014, DOI: 10.1109/JLT.2014.2365187
Abstract: We observe an interference pattern using a simple fiber-optic interferometer consisting of an electrical spectrum analyzer and a narrowband light source, which is commonly employed for observing the Brillouin gain spectrum. This interference pattern expands well beyond the frequency range corresponding to the Brillouin frequency shift in silica fibers (approximately 11 GHz at 1550 nm). Using both silica single-mode and polymer optical sensing fibers, we then experimentally prove that the distinctive noise in a self-heterodyne-based Brillouin measurement with an unoptimized polarization state originates from the interference between the reference light and the Fresnel-reflected light. This noise can be almost completely suppressed by employing a delay line that is longer than the coherence length of the light source and by artificially applying a high loss near the open end of the sensing fiber.
Measurement of the Elasticooptic Effect of Crystal Using Fiber White-light Interferometry

XING Jin-hua,QIAN Bin,FENG Jin-fu,

光子学报 , 2007,
Abstract: Starting from the index ellipsoid,the elasticooptic effect of crystal is analyzed.The relation between the stress along the optical axis of trigonal crystallographic system and the refractive index is established.The optical property of crystal is anisotropic and the change of refractive index with the stress is little.The ability of the white-light interferometry is explored to measure the refractive index of anisotropic material using high spatial resolving power of the white-light interferometry.Moreover,an improved method using white-light interferometry and all polarization-maintaining fiber Michelson interferometer to measure group refractive index is introduced, using grating displacement sensor to increase the displacement precision of scanning mirror.The change of quartz crystal refractive index is measured under the different outside force,and the elasticooptic coefficient is determined.The elasticooptic coefficients of quartz crystal P33 and P13 are 0.110 and 0.279 respectively,the precision reaches 0.001.
Loop topology based white light interferometric fiber optic sensor network for application of perimeter security
Libo Yuan,Yongtao Dong
Photonic Sensors , 2011, DOI: 10.1007/s13320-010-0009-9
Abstract: A loop topology based white light interferometric sensor network for perimeter security has been designed and demonstrated. In the perimeter security sensing system, where fiber sensors are packaged in the suspended cable or buried cable, a bi-directional optical path interrogator is built by using Michelson or Mach-Zehnder interferometer. A practical implementation of this technique is presented by using an amplified spontaneous emission (ASE) light source and standard single mode fiber, which are common in communication industry. The sensor loop topology is completely passive and absolute length measurements can be obtained for each sensing fiber segment so that it can be used to measure quasi-distribution strain perturbation. For the long distance perimeter monitoring, this technique not only extends the multiplexing potential, but also provides a redundancy for the sensing system. One breakdown point is allowed in the sensor loop because the sensing system will still work even if the embedded sensor loop breaks somewhere.
Nanoporous Zeolite Thin Film-Based Fiber Intrinsic Fabry-Perot Interferometric Sensor for Detection of Dissolved Organics in Water  [PDF]
Ning Liu,Juan Hui,Cunqiang Sun,Junhang Dong,Luzheng Zhang,Hai Xiao
Sensors , 2006, DOI: 10.3390/s6080835
Abstract: A fiber optic intrinsic Fabry-Perot interferometric (IFPI) chemical sensor wasdeveloped by fine-polishing a thin layer of polycrystalline nanoporous MFI zeolitesynthesized on the cleaved endface of a single mode fiber. The sensor operated bymonitoring the optical thickness changes of the zeolite thin film caused by the adsorption oforganic molecules into the zeolite channels. The optical thickness of the zeolite thin filmwas measured by white light interferometry. Using methanol, 2-propanol, and toluene as themodel chemicals, it was demonstrated that the zeolite IPFI sensor could detect dissolvedorganics in water with high sensitivity.
Nonlinear Distortion of the Fiber Optic Microphone  [PDF]
Muhammad Taher Abuelma'atti
Active and Passive Electronic Components , 2000, DOI: 10.1155/apec.23.1
Abstract: Analytical expressions are obtained for predicting the harmonic and intermodulation performance of the fiber optic microphone. These expressions are in terms of the ordinary Bessel functions with arguments dependent on the amplitudes of the acoustical exciting signal.
Interferometric Fiber Optic Sensors  [PDF]
Byeong Ha Lee,Young Ho Kim,Kwan Seob Park,Joo Beom Eom,Myoung Jin Kim,Byung Sup Rho,Hae Young Choi
Sensors , 2012, DOI: 10.3390/s120302467
Abstract: Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.
Fiber Optic Broadband Ultrasonic Probe for Virtual Biopsy: Technological Solutions  [PDF]
E. Biagi,S. Cerbai,L. Masotti,L. Belsito,A. Roncaglia,G. Masetti,N. Speciale
Journal of Sensors , 2010, DOI: 10.1155/2010/917314
Abstract: An ultrasonic probe was developed by using, in conjunction, optoacoustic and acousto-optic devices based on fiber optic technology. The intrinsic high frequency and wide bandwidth associated both to the opto-acoustic source and to the acousto-optic receiving element could open a way towards a “virtual biopsy” of biological tissue. A Micro-Opto-Mechanical-System (MOMS) approach is proposed to realize the broadband ultrasonic probe on micromachined silicon frames suited to be mounted on the tip of optical fibers. 1. Introduction Much recent progress in clinical applications of echography demands for miniaturized and wide bandwidth ultrasonic probes. Wide band ultrasound leads to improved spatial resolution; in addition, it allows spectral analysis of echo signals, a technique that resulted to be effective in clinical diagnosis [1]. However, the diagnostic power of this technique strongly depends on the available ultrasonic bandwidth for differentiating media, due to their frequency-selective interaction. Our group proposed the design and realization of an ultrasonic source based on optoacoustic effect in 1996, with a metal layer over the fiber optic tip as absorbing target [2]. In 2001 we improved, of about two orders of magnitude, the optoacoustic conversion by replacing the metal absorbing target with a graphite one [3, 4]. Other configurations have been developed based on this principle: some make use of graphite powder dispersed in polymeric materials, others require the use of nanostructured materials with gold dipped in polymer matrices [5]. This solution presents the advantage of further extending the band, but has a complicated implementation and requires the use of pulsed laser optical sources, because it exhibits a fairly narrow range of optical absorption. This implies a very complicated and expensive technology. The transmitting element, depicted in Figure 1, is constituted by a fiber optic on whose tip an absorbing layer is deposed; Thermo-elastic Ultrasound Generation (TUG) takes place when the laser pulse hits this absorbing thin layer and the induced thermal expansion generates a mechanical shock wave. Figure 1: Fiber optic ultrasonic source based on optoacoustic conversion. Two years later, in 2003, we proposed a complete ultrasonic probe by adding a receiving element, based on fiber optic [6]. Several kinds of ultrasonic reception methods by optical interferometry have been proposed in the literature. Almost all use fiber optics to transmit light radiation, but differ in the method of demodulation. In some, the demodulation is carried
Optical Fiber Networks for Remote Fiber Optic Sensors  [PDF]
Montserrat Fernandez-Vallejo,Manuel Lopez-Amo
Sensors , 2012, DOI: 10.3390/s120403929
Abstract: This paper presents an overview of optical fiber sensor networks for remote sensing. Firstly, the state of the art of remote fiber sensor systems has been considered. We have summarized the great evolution of these systems in recent years; this progress confirms that fiber-optic remote sensing is a promising technology with a wide field of practical applications. Afterwards, the most representative remote fiber-optic sensor systems are briefly explained, discussing their schemes, challenges, pros and cons. Finally, a synopsis of the main factors to take into consideration in the design of a remote sensor system is gathered.

Ye Wei,Zhou Kejiang,

光子学报 , 2000,
Abstract: Based on the calculation and analysis of the auto-correlation function of the noise in fiber optic gyros (FOG), the noise model which is addition of Gaussian white noise (GWN) and fractal Brownian motion (FBM) is analyzed by an algorithm of orthonormal wavelet transform. An important conclusion is presented that the FBM dominates the noise in high performance fiber optic gyros. The noise sources are analyzed and the fiber gyros system is developed.
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