Fiber Optics Research Papers - Academia.edu (original) (raw)

In recent years, several New England projects have promoted professional development and curriculum design in optics and photonics. Funded in part by the Advanced Technological Education (ATE) program of the National Science Foundation... more

In recent years, several New England projects have promoted professional development and curriculum design in optics and photonics. Funded in part by the Advanced Technological Education (ATE) program of the National Science Foundation (NSF), these projects have prepared middle and high school teachers, college faculty and career counselors from more than 100 New England institutions to introduce fiber optics, telecommunications and photonics technology education. Four of these projects will be discussed here: (1) The New England Board of Higher Education's (NEBHE) Fiber Optics Technology Education Project, (FOTEP) was designed to teach fiber optics theory and to provide laboratory experiences at the secondary and postsecondary levels. (2) Springfield Technical Community College's Northeast Center for Telecommunications Technologies (NCTT) is developing curricula and instructional materials in lightwave, networking and wireless telecommunications technologies. (3) The Harvard-Smithsonian Center for Astrophysics project ComTech developed a 12-week, hands-on curriculum and teaching strategies for middle and high school science and technology teachers in telecommunications and focused on optical communication (fiber optics). (4) NEBHE's project PHOTON is preparing middle, secondary and postsecondary instructors to introduce theory and laboratory experiences in photonics, including geometric and wave optics as well as principles of lasers and photonics applications.

This paper reports on the use of cellulose paper simultaneously as electrolyte, separation of electrodes, and physical support of a rechargeable battery. The deposition on both faces of a paper sheet of metal or metal oxides thin layers... more

This paper reports on the use of cellulose paper simultaneously as electrolyte, separation of electrodes, and physical support of a rechargeable battery. The deposition on both faces of a paper sheet of metal or metal oxides thin layers with different electrochemical potentials, respectively as anode and cathode, such as Cu and Al, lead to an output voltage of 0.70 V and a current density that varies between 150 nA/cm 2 and 0.5 mA/cm 2 , subject to the paper composition, thickness and the degree of OH x species adsorbed in the paper matrix. The electrical output of the paper battery is independent of the electrodes thickness but strongly depends on the atmospheric relative humidity (RH), with a current density enhancement by more than 3 orders of magnitude when RH changes from 60% to 85%. Besides flexibility, low cost, low material consumption, environmental friendly, the power output of paper batteries can be adapted to the desired voltage-current needed, by proper integration. A 3-V prototype was fabricated to control the ON/OFF state of a paper transistor.

This work presents a detailed review of the development of distributed acoustic sensors (DAS) and their newest scientific applications. It covers most areas of human activities, such as the engineering, material, and humanitarian... more

This work presents a detailed review of the development of distributed acoustic sensors (DAS) and their newest scientific applications. It covers most areas of human activities, such as the engineering, material, and humanitarian sciences, geophysics, culture, biology, and applied mechanics. It also provides the theoretical basis for most well-known DAS techniques and unveils the features that characterize each particular group of applications. After providing a summary of research achievements, the paper develops an initial perspective of the future work and determines the most promising DAS technologies that should be improved.

The maximum distance to which the secondary mirror can be moved with respect to its primary in a true Cassegrain telescope with limited image deterioration is found to be proportional to the fourth power of the focal ratio of the primary... more

The maximum distance to which the secondary mirror can be moved with respect to its primary in a true Cassegrain telescope with limited image deterioration is found to be proportional to the fourth power of the focal ratio of the primary mirror. This limit is independent of all other parameters describing the system when the magnification of the secondary is greater than about 3.

It is shown that the Fraunhofer diffraction pattern of a tilted aperture screen can be interpreted as a ' monocular view of the Ewald sphere. Two of those patterns recorded at opposite tilting angles are used to give a stereoscopic... more

It is shown that the Fraunhofer diffraction pattern of a tilted aperture screen can be interpreted as a ' monocular view of the Ewald sphere. Two of those patterns recorded at opposite tilting angles are used to give a stereoscopic impression of the Ewald sphere. Experimental results are shown, and the approximations involved are discussed.

An hybrid atomic force-scanning near-field optical microscope (AFM-SNOM) has been realized starting from a home-built AFM. The instrument uses a tetrahedral SiN tip for force and near field detection and is designed to provide, besides... more

An hybrid atomic force-scanning near-field optical microscope (AFM-SNOM) has been realized starting from a home-built AFM. The instrument uses a tetrahedral SiN tip for force and near field detection and is designed to provide, besides simple imaging, a full three-dimensional (3-D) mapping of force, friction and light intensity on the sample. High-resolution optical images of dielectric samples are presented together with curves describing the behavior of the collected optical intensity as a function of tip-object distance. AFM images and forcedistance curves are reported as well and are compared with those obtained from the optical channel. Subwavelength features of the samples can be easily appreciated in both kinds of images, and the refractive index of the object can be computed from the attenuation constant of the tunneling light detected by the tip, with the AFM curve providing a convenient way of detecting the contact point. The spatial resolution of this kind of measurement is far better than that obtainable with any other index-measuring device. Homogeneous glass samples as well as monomode channel waveguides were analyzed in our experiments. The refractive index of several different prisms, made either of BK7 (n = 1:519 at = 532 nm) or of SF58 (n = 1:932) glass, could be measured with our near-field technique. As for the channel waveguides, the accuracy of our measurements lets us detect their presence and lateral extension in the substrate but is not yet sufficient to allow the reconstruction of their index profile.

A theory is presented which relates the minimum detectable contrast level for an object in the presence of noise to the statistics of the speckle. Consideration is given to smoothing of the noise by multiple looks and by area.... more

A theory is presented which relates the minimum detectable contrast level for an object in the presence of noise to the statistics of the speckle. Consideration is given to smoothing of the noise by multiple looks and by area. Measurements of the minimum detectable contrast are made for two types of speckle noise. First, a coherent, plane wave is added to an ideal diffuse wave and the threshold of detection is established as a function of the beam ratio. Secondly, these results are compared to the technique of speckle smoothing using an N-fold intensity superposition of fully developed theory is observed.

A theory of the influence of measurement conditions on temperature measurement accuracy with infrared systems has been recently presented. A comparison study of the shortwave 13-5-µm2 and longwave 18-12-µm2 measuring IR cameras was... more

A theory of the influence of measurement conditions on temperature measurement accuracy with infrared systems has been recently presented. A comparison study of the shortwave 13-5-µm2 and longwave 18-12-µm2 measuring IR cameras was conducted on the basis of this theory. The results of the simulations show that the shortwave systems in typical measurement conditions generally offer better accuracy in temperature measurement than do the longwave systems. Some experiments that use a commercially available IR camera were carried out to verify the theory. The results of these experiments and a discussion about the theory limitations are presented.

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the... more

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing. Video Link The video component of this article can be found at https://www.jove.com/video/51483/ 7,8. Dual laser systems are also customizable as the user can add or remove components (e.g., external shutters, beam filters, inline power meters) from the beam path as required. Due to its versatility, the dual laser setup is recommended if optogenetics is going to be a continued tool used in the lab. Coupling of the lasers, however, can present a challenge and so a quick, easy, and reliable coupling mechanism is provided in this protocol. Note, this protocol details the assembly of optical components and utilizes patch cords and components that are optimized for step-index multimode fibers with a 200 μm core and a numerical aperture (NA) of

Two twelve-channel arrays based on surface-etched slot gratings, one with nonuniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm,... more

Two twelve-channel arrays based on surface-etched slot gratings, one with nonuniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm, with a side-mode suppression ratio (SMSR) > 40 dB over much of this range and output power greater than 20 mW, was obtained for the array with non-uniform slots over a temperature range of 15°C-60°C. The introduction of multiple slot periods, chosen such that there is minimal overlap among the side reflection peaks, is employed to suppress modes lasing one free spectral range (FSR) from the intended wavelength. The tuning range of the array with uniformly spaced slots, on the other hand, was found to be discontinuous due to mode-hopping to modes one FSR away from the intended lasing mode which are not adequately suppressed. Spectral linewidth was found to vary across devices with the lowest measured linewidths in the range of 2 MHz to 4 MHz.

slides about optical communication system

We model the double phase-conjugate mirror (DPCM) as a function of time, the average direction of propagation of the two beams forming the DPCM, and one transverse coordinate. Calculations show that the conjugation fidelity and... more

We model the double phase-conjugate mirror (DPCM) as a function of time, the average direction of propagation of the two beams forming the DPCM, and one transverse coordinate. Calculations show that the conjugation fidelity and reflectivity have different dependencies on the photorefractive coupling coefficient times length; the fidelity turns on abruptly with a threshold, whereas the reflectivity increases smoothly. The DPCM behaves as an oscillator at and above threshold: the time required for the reflectivity to reach the steady state dramatically slows down near threshold (like critical slowing down in lasers); above threshold the DPCM is self-sustaining even if the random noise terms used to start the process are set to zero. A decrease in the noise level improves the fidelity but increases the response time. The use of unbalanced input beam ratios results in asymmetric conjugation such that the fidelity obtained on the side of the weaker input beam is significantly reduced. The slowing down diminishes with increasing noise level or unbalanced input intensities.

A coherent processor is presented which is capable of performing a large class of 1-D linear space-variant operations. The only components of the processor are a 1-D input, a mask whose transmittance is specified by the desired linear... more

A coherent processor is presented which is capable of performing a large class of 1-D linear space-variant operations. The only components of the processor are a 1-D input, a mask whose transmittance is specified by the desired linear operation, and an output plane. Compared with other 1-D processors, this processor has advantages of real space compactness and total elimination of vignetting. Experimental results are presented for the specific operations of convolution and spectrum scaling.

An experiment to investigate the potential of a laser-induced plasma method for determining concrete compressive strength was conducted by focusing a Nd:YAG laser on concrete samples with different degrees of compressive strength. This... more

An experiment to investigate the potential of a laser-induced plasma method for determining concrete compressive strength was conducted by focusing a Nd:YAG laser on concrete samples with different degrees of compressive strength. This technique was developed in light of the role of the shock wave in the generation of a laser-induced plasma. It was found that the speed of the shock front depends on the hardness of the sample. It was also found that a positive relationship exists between the speed of the shock front and the ionization rate of the ablated atoms. Hence, the ratio of the intensity between the Ca(II) 396.8 nm and Ca(I) 422.6 nm emission lines detected from the laser-induced plasma can be used to examine the hardness of the material. In fact, it was observed that the ratio changes with respect to the change in the concrete compressive strength. The findings also show that the ratio increases with time after the cement is mixed with water.

An external reflection scanning near-field optical microscope with shear force regulation of the tip-surface distance is described. Near-field optical and shear force topographical images are compared for various samples. It is shown that... more

An external reflection scanning near-field optical microscope with shear force regulation of the tip-surface distance is described. Near-field optical and shear force topographical images are compared for various samples. It is shown that the most important correlative relationships between these images can be deduced from symmetry considerations. The possibility of extracting additional information from the optical images is demonstrated on images of human blood cells.

We present a model of energy consumption in IP networks. Using this model, we identify energy ldquohotspotsrdquo and estimate how energy consumption will grow with increasing network capacity. Todaypsilas Internet uses less than 1% of the... more

We present a model of energy consumption in IP networks. Using this model, we identify energy ldquohotspotsrdquo and estimate how energy consumption will grow with increasing network capacity. Todaypsilas Internet uses less than 1% of the available electricity supply. However, network energy consumption could grow substantially as access rates increase.

Most confocal microscopes do not produce images in real time with nonlaser light sources. The tandem scanning confocal microscope does produce such images but, because the pinhole apertures of the Nipkov disk must be placed far apart to... more

Most confocal microscopes do not produce images in real time with nonlaser light sources. The tandem scanning confocal microscope does produce such images but, because the pinhole apertures of the Nipkov disk must be placed far apart to reduce cross talk between neighboring pinholes, only 1% or less of the light available for imaging is used. We show that, by using aperture correlation techniques and relaxing the requirement to obtain a pure confocal image directly, one can obtain real-time confocal images with a dramatically increased (25% or even 50%) light budget.

Summary form only given. Telecommunications has continued to push optical fibers towards ever-more demanding applications-such as high bit rates, dense wavelength-division multiplexing (DWDM), and long distances-and in response there has... more

Summary form only given. Telecommunications has continued to push optical fibers towards ever-more demanding applications-such as high bit rates, dense wavelength-division multiplexing (DWDM), and long distances-and in response there has been renewed interest in alternative fiber designs to lift fundamental limitations of silica fibers. A particularly exciting departure from traditional fibers are fibers based on photonic band gaps, forbidden frequency

The Fraunhofer diffraction pattern of an aperture function, which can be described in terms of the superposition of a known aperture function with a half plane, has an amplitude distribution which is real along one direction and complex... more

The Fraunhofer diffraction pattern of an aperture function, which can be described in terms of the superposition of a known aperture function with a half plane, has an amplitude distribution which is real along one direction and complex along the orthogonal direction. The real and imaginary parts of the amplitude distribution are related by Hubert transforms (dispersion relations). These disper sion relations can be used to arrive at the diffraction patterns of a variety of apertures having symmetry properties. Theoretical results are presented to illustrate the diffraction pattern of various apertures.

Using our new negative Δ LC material in a fringing field switching (n-FFS) cell, we demonstrated superior performances to conventional positive Δ FFS (p-FFS) LCD in transmittance, viewing angle, cell gap sensitivity, gamma curve, while... more

Using our new negative Δ LC material in a fringing field switching (n-FFS) cell, we demonstrated superior performances to conventional positive Δ FFS (p-FFS) LCD in transmittance, viewing angle, cell gap sensitivity, gamma curve, while keeping a comparable operation voltage and response time. Therefore, n-FFS has potential to replace p-FFS for next-generation mobile displays.

Following the development and publication of the JCAMP-DX protocol 4.24 and its successful implementation in the field of infrared spectroscopy, data exchange without loss of information, between systems of different origin and internal... more

Following the development and publication of the JCAMP-DX protocol 4.24 and its successful implementation in the field of infrared spectroscopy, data exchange without loss of information, between systems of different origin and internal format, has become a reality. The benefits of this system-independent data transfer standard have been recognized by workers in other areas who have expressed a wish for an equivalent, compatible standard in their own fields. This publication details a protocol for the exchange of Nuclear Magnetic Resonance (NMR) spectral data without any loss of information and in a format that is compatible with all storage media and computer systems. The protocol detailed below is designed for spectral data transfer, and its use for NMR imaging data transfer has not as yet been investigated.

A large area, charge-couple-device (CCD) based fiberoptic taper array detector (APS-1) has been installed at the insertion-device beamline of the Structural Biology Center at the ANL Advanced Photon Source. The detector is used in protein... more

A large area, charge-couple-device (CCD) based fiberoptic taper array detector (APS-1) has been installed at the insertion-device beamline of the Structural Biology Center at the ANL Advanced Photon Source. The detector is used in protein crystallography diffraction experiments, where the objective is to measure the position and intensity of X-ray Bragg peaks in diffraction images. Large imaging area, very high spatial resolution, high X-ray sensitivity, good detective quantum efficiency, low noise, wide dynamic range, excellent stability and short readout time are all fundamental requirements in this application. The APS-1 detector converts the two-dimensional X-ray patterns to a visible light images by a thin layer of Xray sensitive phosphor. The phosphor coating is directly deposited on the large ends of nine fiberoptic tapers arranged in a 3x3 array. Nine; thermoelectrically cooled 1024 x 1024 pixel CCD's image the patterns, demagnified by the tapers. After geometrical and uniformity corrections, the nine areas give a continuous image of the detector face with virtually no gaps between the individual tapers. The 18 parallel analog signal-processing channels and analog-to-digital converters assure short readout time and low readout noise.

A simple apparatus for time-correla ted single photon counting (TCSPC) m easurements in the near-infrared (near-IR) region for scanning-type applications has been constructed and examined. The apparatus consisted of ® ve m ajor com... more

A simple apparatus for time-correla ted single photon counting (TCSPC) m easurements in the near-infrared (near-IR) region for scanning-type applications has been constructed and examined. The apparatus consisted of ® ve m ajor com ponents including a pulsed diode laser source (lasing wavelength 5 780 nm; rep etition rate 5 80 MHz; power 5 5 mW ; pulse width 5 150 ps), an integrated m icroscope, a large-photoactive-area avalanche photodiode (APD), a TCSPC PC-board including the electron ics, and a Windows-based software package for accu mulating the¯uorescen ce decay pro® les. The instrument response function (IRF) of this assembly was found to be 460 ps, which is adequate for measuring lifetim es with t f $ 500 ps. Due to the sm all size of the device, it also allowed implem entation into scanning experim ents where lifetimes were measured. To dem onstrate this capability, we scanned a three-well microscope slide containing a near-IR dye. The decay pro® le of the near-IR dye, aluminum 2,3-naphthalocyanine, was collected and analyzed to obtain its lifetime, which was found to be 2.73 ns, in close agreement with the literature value for this particular dye. In addition, a three-dim ensional plot showing the decay pro® les (tim e vs. photocounts) and scan position of aluminum 2,3-naphthalocyaninē uorescence was acquired by scanning the m icroscope head over this three-well glass slide. In the scanning m ode, the IRFs as well as the decays of the dyes were found to be very stable. The device dem onstrated a concentration detection sensitivity of 0.44 nM; however, the dynamic range was limited due to the slow tim e constant (passive quenching) associated with the APD.

The necessary and sufficient conditions on the gain of the linear amplifier are determined under which the light output exhibits sub-Poissonian photon statistics or squeezing. It is found that for these effects the intensity gain must not... more

The necessary and sufficient conditions on the gain of the linear amplifier are determined under which the light output exhibits sub-Poissonian photon statistics or squeezing. It is found that for these effects the intensity gain must not exceed 2 under any circumstances. It is also shown that there exists a weaker sufficiency condition on the gain above which all nonclassical features of the field disappear. This suggests the possibility that other quantum effects may persist in the intermediate, still unexplored, domain of operation of the amplifier.

Mean-variance analysis is described as a method for characterization of the read-noise and gain of focal plane array (FPA) detectors, including charge-coupled devices (CCDs), charge-injection devices (CIDs), and complementary... more

Mean-variance analysis is described as a method for characterization of the read-noise and gain of focal plane array (FPA) detectors, including charge-coupled devices (CCDs), charge-injection devices (CIDs), and complementary metal-oxide-semiconductor (CMOS) multiplexers (infrared arrays). Practical FPA detector characterization is outlined. The nondestructive readout capability available in some CIDs and FPA devices is discussed as a means for signal-tonoise ratio improvement. Derivations of the equations are fully presented to unify understanding of this method by the spectroscopic community.

An economical and viable option to conventional and high rate materials is the use of fiber glass/epoxy composites, but for impact applications their toughness still has to be enhanced. The toughness and additional mechanical properties... more

An economical and viable option to
conventional and high rate materials is the use of
fiber glass/epoxy composites, but for impact
applications their toughness still has to be enhanced.
The toughness and additional mechanical properties
can be improved by using very small amount of PET
into an epoxy system. In the present work epoxy
modified by way of MMT Clay (3 wt % of Epoxy)
& PET fiber is manufactured using hand layup
system. The nano composites have been
characterized using Impact, Tensile, Bending and
Microhardness tests. The mechanical properties are
compared by means of those found for PET
introduced epoxy nano composites. The mechanical
test shows that the presence of 1 wt% PET fiber
largely increases impact strength and flexural
strength. Micro hardness decreased at PET fiber
loading.

In this paper, we deal with the subject of cross-gain modulation (XGM) and cross-phase modulation (XPM) semiconductor optical amplifier-based wavelength conversion of optical channels carrying subcarrier multiplexing signals in a... more

In this paper, we deal with the subject of cross-gain modulation (XGM) and cross-phase modulation (XPM) semiconductor optical amplifier-based wavelength conversion of optical channels carrying subcarrier multiplexing signals in a comprehensive way. The equations and models that describe the conversion process and the resulting harmonic and intermodulation distortions are obtained showing the superior performance of XPM over XGM in terms of second-and third-order distortion and contrast ratio. Experimental results for XGM-based wavelength conversion that confirm the results predicted by our theoretical models are presented, and finally, we consider the specific application of wavelength conversion of optical channels carrying full frequency plans such as that of cable television applications.

Raman spectroscopy has been well established as a powerful method for studying biological tissues and diagnosing diseases. In this study we have developed a breast cancer animal model and collected in vivo Raman spectra of mammary glands... more

Raman spectroscopy has been well established as a powerful method for studying biological tissues and diagnosing diseases. In this study we have developed a breast cancer animal model and collected in vivo Raman spectra of mammary glands of 27 Sprague-Dawley female rats treated with DMBA and 5 non-treated used as control group. A dispersive Raman spectrometer with a @785 nm laser excitation coupled a fiber optic probe and a CCD detector was used to obtain the spectra. The obtained in vivo transcutaneous Raman spectra have shown important differences between normal and abnormal tissues when acquired from one side to the other side of the lesion.

The points at which two-dimensional spectra of band-limited functions are zero can be used to generate a polynomial approximation of the complex spectrum. These point-zero locations are common to both the spectrum and the associated power... more

The points at which two-dimensional spectra of band-limited functions are zero can be used to generate a polynomial approximation of the complex spectrum. These point-zero locations are common to both the spectrum and the associated power spectrum. The phase of the complex-valued polynomial along with the measured intensity data is used to generate an initial guess for the function that an error-reduction algorithm can improve. This approach has practical utility for Fourier phase retrieval as well as for blind deconvolution. The limitations of the model are discussed, and examples are given.

Metal-organic semiconductor films are fabricated as co-evaporated films. It is demonstrated that the technique can be used to fabricate metalsemiconductor surface-enhanced Raman scattering (SERS) or surfaceenhanced resonance Raman... more

Metal-organic semiconductor films are fabricated as co-evaporated films. It is demonstrated that the technique can be used to fabricate metalsemiconductor surface-enhanced Raman scattering (SERS) or surfaceenhanced resonance Raman scattering (SERRS) substrates or to attain SERS or SERRS of highly insoluble pigments. The experiments are carried out using three different pigments: iron phthalocyanine (FePc) and two substituted tetracaboxylic perylenes (PTCDs). The structure of the co-PVD films was characterized at the nanoscale by scanning electron microscopy through field-emission gun (SEM-FEG), revealing a fairly homogeneous spatial distribution of the silver-pigment nanoparticles. The fabricated mixed nanostructures show a homogenous distribution of plasmon enhancement as observed in the point-by-point mapping of the SERRS spectra recorded with micrometer spatial resolution in Raman microscopy.

Optical characterization of three red pigments, two organic and one inorganic, was studied in order to provide important and reliable parameters for research and applications. The pigments were C.I. Pigment Red 176, C.I. Pigment Red 57:1,... more

Optical characterization of three red pigments, two organic and one inorganic, was studied in order to provide important and reliable parameters for research and applications. The pigments were C.I. Pigment Red 176, C.I. Pigment Red 57:1, and C.I. Pigment Red 101. All three pigments were used in their transparent form, that is, their radius of gyration was smaller than 250 nm. The particles were suspended in an apolar solvent and absorption, reflection, and scattering of the suspensions were measured by means of a single spectrophotometer and the effective complex refractive index was determined.

A previously unknown form of compromising emanations has been discovered. LED status indicators on data communication equipment, under certain conditions, are shown to carry a modulated optical signal that is significantly correlated with... more

A previously unknown form of compromising emanations has been discovered. LED status indicators on data communication equipment, under certain conditions, are shown to carry a modulated optical signal that is significantly correlated with information being processed by the device. Physical access is not required; the attacker gains access to all data going through the device, including plaintext in the case of data encryption systems. Experiments show that it is possible to intercept data under realistic conditions at a considerable distance. Many different sorts of devices, including modems and Internet Protocol routers, were found to be vulnerable. A taxonomy of compromising optical emanations is developed, and design changes are described that will successfully block this kind of "Optical TEMPEST" attack.

A novel fiber Bragg grating (FBG) sensing multiplexing system based on the combination of InGaAs spectrometer and Fabry-Perot (F-P) filter (InGaAs/F-P) is proposed. The multiplexing system only demodulates FBG sensors whose peak... more

A novel fiber Bragg grating (FBG) sensing multiplexing system based on the combination of InGaAs spectrometer and Fabry-Perot (F-P) filter (InGaAs/F-P) is proposed. The multiplexing system only demodulates FBG sensors whose peak wavelengths are shifting. The demodulation can be sequenced according to each sensor's priority, latency time and wavelength shifting. What is more, the monitor section of that system is not influenced by environmental temperature and source intensity fluctuations. At the average signal repeat rate of 6Hz, the average delay time of the conventional wavelength-and spatial-division combined system, the long period grating (LPG) combined system and the InGaAs/F-P system are 303, 97, and 6 ms, respectively. Simulation analysis and experiment work demonstrated that the InGaAs/F-P system is more rational and smart than other counterparts.

The fixed oil of Laurus novocanariensis (previously L. azorica) contains mostly glycerides together with minor non-saponifiable compounds. The direct identification and quantitative determination of costunolide and dehydrocostuslactone,... more

The fixed oil of Laurus novocanariensis (previously L. azorica) contains mostly glycerides together with minor non-saponifiable compounds. The direct identification and quantitative determination of costunolide and dehydrocostuslactone, two sesquiterpene lactones components of the oil that exhibit biological activities, is described. The analysis was carried out using 13 C-NMR spectroscopy (signal acquisition with inverse gated decoupling of protons; diglyme as internal standard) without separation, derivatisation or any sample preparation.

This paper is concerned with the development of Fourier transform spectroscopy from its beginnings in Michelson's visibility technique through the present day application using modern digital computers. Methods used in maximizing the... more

This paper is concerned with the development of Fourier transform spectroscopy from its beginnings in Michelson's visibility technique through the present day application using modern digital computers. Methods used in maximizing the efficiency of the computation, as well as the interferometer, are discussed.

The continuing growth of telecommunication networks is currently dominated by fiber optics (or optical networking). Optical fiber has become the guided medium of choice in telecommunications, and associated optoelectronic technologies... more

The continuing growth of telecommunication networks is currently dominated by fiber optics (or optical networking). Optical fiber has become the guided medium of choice in telecommunications, and associated optoelectronic technologies have become important such as optical fiber itself and optical amplifiers. Optical amplifiers can operate in the long distance using fiber optic carrying data and information in communication links. Some mechanisms are able to amplify electromagnetic signal corresponding to kinds of optical amplifiers. In doped fiber amplifiers and bulk laser sources, a stimulated emission in the amplifier's gain media causes amplification of incoming electromagnetic spectrum. In semiconductor optical amplifier (SOA), electron-hole interaction will occur. For Raman amplifier (RA), its scattering of incoming source with phonons in the lattice of the gain media will produce photons coherent with the incoming photons. Using the simulation, both amplifiers are simulated and compared by in-line amplifiers to allow and keep a better signal from material and geometry disturbance.

Optical fiber offers many advantages over coaxial cable for the transmission of radio frequency ͑rf͒ signals in antenna-remoting applications, as well as cellular networks and cable television ͑CATV͒ signal distribution networks. Optical... more

Optical fiber offers many advantages over coaxial cable for the transmission of radio frequency ͑rf͒ signals in antenna-remoting applications, as well as cellular networks and cable television ͑CATV͒ signal distribution networks. Optical fiber shows significantly less loss, can support signals demanding much higher bandwidth, is immune to electromagnetic interference ͑EMI͒, and enables considerable size and weight savings when compared to coaxial cable. Free-space optics ͑FSO͒ communications is a technology that uses modulated optical beams to transmit information line of sight through the atmosphere. FSO can be deployed faster and cheaper when compared with optical fiber. Recently, FSO has been investigated by the telecommunications industry and research centers to transport digital signals for civilian "last mile" applications and military applications. We demonstrate the successful transport of modulated rf analog signals over an FSO link and compare key performance measures against a fiber optic link configured in an identical manner. Results of measurements of optical power, transmission response, reflection response, group delay that defines phase distortion, carrier-to-noise ratio ͑CNR͒, and dynamic range that defines nonlinear distortion are presented. Results from this comparative study indicate that FSO for rf applications is a suitable replacement for fiber optic transmission links over short distances.

In recent years, fiber optics has found major applications in sensor technology. In this paper, we develop a theoretical analysis on different configurations of couples of fibers, in order to determine the optimal configuration for a... more

In recent years, fiber optics has found major applications in sensor technology. In this paper, we develop a theoretical analysis on different configurations of couples of fibers, in order to determine the optimal configuration for a position sensor, which allows us to measure displacements in the order of microns. This sensor is based on intensity modulated sensor and can be

An improved photoelastic modulator (PEM) employing two piezoelectric transducers and incorporating a new ir zinc selenide (ZnSe) optical element is described. The 0.64-cm thick PEM is capable of obtaining quarter-wave retardation from... more

An improved photoelastic modulator (PEM) employing two piezoelectric transducers and incorporating a new ir zinc selenide (ZnSe) optical element is described. The 0.64-cm thick PEM is capable of obtaining quarter-wave retardation from 0.55 im to 13.0 ,um. Previously no single, high quality, low static strain PEM element existed for this wavelength range. We have also constructed other PEM's using optical elements composed of fused quartz, calcium fluoride, and KRS-5. The important optical and mechanical properties are measured and compared.

Turbidity is one of most important water-quality parameters; turbidity measurement and removal is as important in water for human use as for industrial-process water. This paper presents a new low cost, small size, and good accuracy... more

Turbidity is one of most important water-quality parameters; turbidity measurement and removal is as important in water for human use as for industrial-process water. This paper presents a new low cost, small size, and good accuracy turbidimeter based upon the use of optical fibers. The design takes advantage of using optical fibers for light transmission, and consequently, waterproof protection becomes unnecessary, remote measurement is feasible, and high signal-to-noise ratio is obtained, decreasing overall uncertainty.