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High intensities electromagnetic energy interacting with organic media gives rise to nonlinear optical effects. Hibiscus Sabdariffa is a flower whose concentrated solution presents interesting nonlinear optical properties. This organic material shows an important self-phase modulation with changes bigger than 2π. We present a diffraction ring patterns study of the Hibiscus Sabdariffa solution. Numerical results of transmittance, with refraction and simultaneous absorption, are shown.

We reported Supercontinuum (SC) generation in standard telecom fiber using picosecond pulses of microchip laser. The pulses width is 700 ps at 1064 nm, using 57 m long of standard fiber, and the spectra extend from 700 to above 1700 nm, some 100 nm further into the visible. The physical processes leading to the formation of the continuum spectrum were studied by monitoring the growth of the SC while increasing the input power. The coupling efficiency of ours experimental setup between the microchip laser and the telecom fiber helped us to obtain this wide spectrum.

Supercontinuum generation is being widely studied due to its applications in communications, medicine and metrology. Usually, special fibers, such as photonic crystal fibers and dispersion-shifted fiber, have been utilized. However, there is few information about the potential use of standard fiber with this purpose, which shows some advantages: low cost and availability. In this work, the influence of losses due to induced macrobends on the supercontinuum generation using standard fiber was studied. The losses were introduced by wrapping 30 m in length of standard fiber on cylinders with different diameter, a nanosecond microchip laser and 1064 nm of wavelength were employed. The continuum was recorded at the fiber output by using an optical spectrum analyzer and its dynamics was analyzed by tuning the launched power. In a first stage, the fiber was used without bends generating strong firs-order Raman Stokes and a supercontinuum spectrum of 636 nm. When the fiber was wrapped in a cylinder of 0.9 cm of diameter to induce macrobends, the Raman Stokes of high order were attenuated and the output spectrum was reduced to 240 nm. Also, a peak pulse was observed, around 1030 nm, that means new frequencies were generated in the near infrared region. Thus, induced macrobends affect the supercontinuum broadening.

We prepare optrodes of fiber optic plastic with sol-gel technique. Suitable concentration of carbone nanotubes (CNTs), phenol red, bromophenol blue and cresol red, design optrodes with fiber optic plastic. The surface charge of silica and the refractive index, which play an important roll on the fiber, modifies the conditions of light propagation into the plastic optical fiber. We use the transmittance to measure the pH of a solution or fluid in a range between 3 and 9.

We propose the fabrication and characterization to bending and temperature of a long period fiber grating with the alternative electric arc method known as fattening. This is the enlargement of the fiber structure by means of arc discharges from a commercial splicing machine. The fiber structure consists of 4 layers of glass of different refractive index. The resulting device is a reject band filter with an attenuation band around 1400nm. It has a bandwidth of 162nm with a depth around 26.9 dB. Test to bending depict changes in band depth up to -10dB between radii values of 4-7cm with a shifting span of 16.8nm. Temperature characterizations are made with bending and straight fiber over a hot surface. Interesting achievements can take advantage as optical sensors with different characteristics. Optimization in the fabrication process can be achieved to lower the insertion losses so better sensors can be applied for industry and commercial applications.

because they are organic salts that are in the liquid state at ambient conditions. The most important ch aracteristic of ILs is that they show negligible vapor pressure, so they are environmentally benign. Nowadays, a large variety of ILs is available. Among other properties, they have thermal stability, high ionic conductivity, miscibility with other solvents, and recyclable nature. On other way, the huge potential of organic materials in optical applications has motivated the development of new compounds and the study of their optical properties, but only few reports on its physicochemical and optical properties have been published

Nonlinear effects are consequence of interaction of height intensities of energy with the matter. Self-diffraction is nonlinear effect and rings are produced. We analyzed the increase of rings due to changes in intensity of CW Ar laser that modify the nonlinear refractive index. The Carbon Nanotubes (CNTs) were dispersed on different solvents: a) water, b) ethanol, c) isoprophanol, and d) acetone. The concentrations were 10ml:1mg in all samples. The dependence between power and concentration of CNTs is shown.

In this paper we propose a high voltage source which is controlled by a communication port I/O of a data acquisition card. The graphical programming language LabView is employed for this task. We make use of this source to produce optical fiber gratings by inducing an electric arc with the point by point procedure. It has a control section to modify the arc duration time and thus the voltage and current applied to the fiber by means of two electrodes. The experimental setup by which we characterized the gratings is depicted and we also present the transmitting spectrum. The gratings were fabricated with SMF-28 fiber but microstructured fiber can be exploited too. These gratings can be used with optical fiber lasers as optical filters and in the implementation of optical sensors.

Design and characterization of a pH optical fiber sensor with a pH sensitive dye is described in this paper. TEOS (Tetra-ethyl-Orto-Silicate) was used to dope a plastic optical fiber, which will be used as the optical probe (OPTRODE). The sensor is prepared by fixing the doped plastic fiber on a fused ortosilica block surface with blue bromophenol. The fiber surface charged with silica modified the refractive index, which plays an important roll on the fiber, modifies the conditions of light propagation into the plastic optical fiber. The fiber transmittance is used to measure the pH of a solution or a fluid in a range between 4 and 7; such signal is captured by a photodetector and processed with a LabView program. The advantage of this system is that, 2cm of doped fiber are enough to measure the pH of a fluid in real time. The time response of the se nsor reported in the present study is approximately 10s. Keywords: Doped fiber, Optical fiber Sensor; pH sensor; Sol-Gel. 1. INTRODUCTION Many industrial sectors have as a need a distributed measurements system for chemical parameters. Early detection and location of water or fluids filtration, for example, could prevent premature damage to cables in both communications and power distribution ducts, in foods industry, biological systems, etc.[1-2]. The detection of some parameters, such pH decreasing to the value of 10, can be a good indicator of potential corrosion of reinforcing tensors in civil engineering structures which are on earth, underground or under water conditions. The definition of pH is the concentr ation of hydrogen ions in liquids. If the pH value is between 0 and 7, are called acids. If the pH values between 7 and 14 are called bases. For pH = 7 the substances are called neutrals, for example pure water, where is very important monitoring for our health. Some biological systems have ionic groups which electrical charge depends on pH concentration; this pH value depends on the balance between the O-H and H. Ther efore, pH is sensitive to the ions concentration in

The photonic crystal (PC) coupler and planar photonic band gap (PBG) coupler were theoretically investigated. Also the conventional step-index coupler was investigated for comparison with these couplers. The PC-coupler is a structure formed by the gradual tapering of the photonic-crystal holey fiber and the conventional step-index coupler -- by the gradual tapering of the conventional fiber. The planar PBG-coupler is a planar PC waveguide, in which defect region has taper-like geometry. The photonic crystal couplers are characterized by alternation of the material refractive index along the wave propagation direction, i. e. along the optical axis of the taper. In our investigation an effective refractive index model for two-dimensional photonic crystal was used. This model allows to analyze the waveguide structures, which work on the effective index waveguiding in a defect of the photonic crystal. The optical field in photonic crystal couplers, PBG couplers and conventional couplers was investigated. Also losses and mode shape distortion of all types of the couplers were calculated.

At the present paper the photonic crystal coupler of an optical fiber, which has been made by the adiabatic tapering of the optical fiber based on the photonic crystal is presented. In our investigation an effective refractive index model of two-dimensional photonic crystal was used. This model allows analyzing the waveguide structures, which work on the effective index waveguiding in a defect of the photonic crystal. The effective refractive indexes of such couplers were numerically found. Using this model the field distribution in these couplers were investigated and were calculated its losses. It was shown that the couplers with smaller input diameter and the fixed output diameter have smaller losses.

This paper is about a numerical investigation of the NOLM (non optical loop mirror) with low birefringence fiber and a0.5/0.5 coupler. We induce birefringence to the loop fiber bias macro bendings considering self rotation polarization of the input beam. This is done in order to find its possible advantages as an optical switch.Keywords: bhfi1ngere,nonhinearqlicalloop * CONACYT Scholarship L INTRODUCHON Birefringence is a single mode fiber characteristic due to core asymmetry. Its effect is the discomposure of an electricalfield in its orthogonal components with a little difference in phase and with a particular polarization. It is also induced by torsion or bending because of the photo elastic effect. For the bending case, an index refraction asymmetry is made,inducing so, the birefringence effect [8]. In this paper, we intend to undertake birefringence basic theory, as to recall investigations made to date about the birefringence effect by means of torsion. This will subsequently lead us to a basicinvestigation of the auto rotation polarization when inducing birefringence by bending a fiber and to analyze differencesbetween torsion and macro bends in the fiber. Thus, we shall achieve a basic investigation contribution about the themeto support later studies and applications.2. ThEORICAL CONSIDERATIONS

We present the polarization dependence in the formation of dark spatial waveguides in nonlinear liquids like CS2. Our experimental and numerical results about the formation of dark waveguides show the dependence between the polarization and the formation of multiple waveguides. With a polarization angle between 100° - 120° for the incident beam we show that the wide of the waveguide is minimum and even dark spatial waveguides are formed. A discussion about waveguides formation is presented for others polarization angles. In this work we show an improvement in the method to measure low birefringence in optical fibers.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this work we showed an improvement in the method to measure low birefringence in optical fibers with the Sagnac interferometer published in paper previous in which the fiber twists in an end of the loop of the interferometer and the entrance of the light every time it is adjusted that twists the fiber. In this work we twist the fiber in the center of the loop of the Sagnac interferometer it is very simple and we don't need light polarization neither to adjust the axes in the entrance of the fiber. It can use for the mensuration a section of shorter fiber that a beat length. Some theoretical and experimental results are presented.

The Sagnac interferometer of twisted low-birefrigence fiber is analyzed numerically in the lineal region. A method for measuring the birefringence of the fiber and the angle of rotation of the axes inside the fiber loop of the interferometer is also presented.

In this work we have shown that Stimulated Raman Scattering can be effectively controlled by a fiber bending losses resulting in spectral dependence of the fiber attenuation.

An experimental investigation of the dynamical, time depends effects in the reflection of (2+1)D beam at the nonlinear interface between photorefractive crystal SBN61:Ce and a linear medium is performed. Our study make emphasis on determining the physical condition under which the beam reflected by the interface is still a focusing beam.

This paper proposes a neural network-based technique for improving the quality of the image fusion as required for the remote sensing (RS) imagery. This proposes to exploit information about the point spread fucntions of the corresonding RS imaging systems combining it with prior realistic knowledge about the properites of teh scene contained in the maximum entropy (ME) a priori image model. Applying the aggregate regularization method to solve the fusion tasks aimed to achieve the best resolution and noise suppression performances of the overall resulting image solves the problem. The proposed fusion method assuems the availability to control the design parameters, which influence the overall restoration performances. Computationally, the fusion method is implemented using the maximum entropy Hopfield-type neural network with adjustable parameters. Simulations illustrate the improved performances of the developed MENN-based fusion method.

We analyze linear and no linear optical properties of PMMA clusters in thin film s with Ni nanoparticles dispersed with different concentrations. Saturable absorber and negative nonlinear refraction index behavior evidences were found using z-scan technique. We also show that these properties have not dependence of the type of matrix but they have on concentration.

We study the reflection of two-dimensional spatial solitons at the nonlinear interface between a saturable nonlinear medium (photorefractive crystal) and a linear medium. Our study places emphasis on determining the experimental conditions under which the beam reflected by the nonlinear interface is still a spatial soliton.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper we report the linear and non-linear properties for PMMA films clusters with nanometrical Silver particles. These samples were prepared by bulk polymerization of methyl metacrylate solution of silver trifluoracetate and followed by post-heating. Varying the concentration ofparticles and using different thermal procedures shown different properties. Third-optical susceptibilities were measured

In this letter, we present an experimental investigation of the influence of light attenuation produced by bending on the generation of Stokes pulse.

We present a numerical study of the reflection of one-dimensional spatial solitons at non-linear interface between a photorefractive medium and a linear medium. In this work, we have considered that non-linear medium is governed by both;drift and diffusion mechanisms. Our study places emphasis on determining the physical conditions under which the beamreflected is still a spatial soliton. The beam is deflected into the interface using the self-bending effect. Introduction Photorefractive crystals (PRC) provided some amazing nonlinear features for low powers light beams. Almost 7 years ago,the first interaction between one-dimensional spatial solitons and PRC was experimentally showed by Duree' et. al. andIturbe2 et. al. for different types of non-linearity. After this, several effects related with solitons in PRC have been studied inorder to develop ultra-fast commuters and optical logic gates3. In the same way, reflection effect of beam light in twodifferent media, when at least one of the media exhibits some kind of optical nonlinearity4 (Kerr, saturable, quadratic, etc.),has been extensively studied5 Recently, Alvarado6 et. al. determined the physical condition under which a spatial soliton isobtained after reflection by an interface non-linear-linear.In this paper we analyze, from numerical and the theoretical point of view, the behavior of one-dimensional brightspatial soliton in a PRC governed by both non-linearities; drift and diffusion, as it reaches the boundary whit a linear mediumusing self-bending effect7.