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A homemade interferometer based on a non-ideal beam splitter and an only one home mirror is presented. Its interference pattern presented dark and bright rings when the mirror was tilted.

We present the fabrication and characterization of a mechanically induced long period grating (MLPG) using a grating period of 400 μm and 1m of NZ-DSF. Pressure is gradually applied up to 120 Lb at different angles like 0, 30, 45 and 60 degrees. An attenuation band is observed centered at a wavelength around 1064nm using a fiber position of 30 degrees with respect to the grating´s metal plate and a maximum pressure of 145 Lb. The loss band presents a maximum depth of 22dB and a bandwidth of approximately 10nm. Torsion and curvature characterizations did not change the output spectrum of the optical grating. However, temperature characterization depicted a small shifting which could be insignificant for some applications. Still, there is 16dB attenuation as temperature increases in a range from room temperature up to 450°C. These preliminary studies show that this 1064 nm centered wavelength MILPG might be used in a low linear dynamic range with temperature (75-300)°C as a temperature sensor.

We study the nonlinear processes involved in the generation of broadband spectra with selectable spectral width. The continuum spectra were generated in short piece of SMF-28 fiber as nonlinear media pumped by a microchip laser at 1064 nm. Bending effects in the spectra were observed through wrapping the fibers on a cylindrical tube. We show that the spectral characteristics directly depend on the properties of the nonlinear medium, the excited nonlinear effects, and the location of the wrapped section which can produce a filtering effect on the SC spectrum. Finally, the main advantages of the proposed scheme are to obtain an adjustable bandwidth for a supercontinuum source through an easy and flexible control, and to provide a low-cost configuration in which photonic crystal fibers are not used.

We show the sensing of load by means mechanically induced long-period fiber grating (MLPFG) made by applying pressure by means a screw to a pair of grooved plates over single-mode fiber. We used a torquemeter in order to obtain precision in the adjustment screw and thus establish an equilibrium pressure applied to a specific region of the optical fiber to form the long-period grating mechanically induced fiber. The increase the torque to screw, the resonance wavelength of MLPFG increases its depth over 16 dB. We use a detector to observe the changes amplitude according to the fiber pressure.

We present the results from the fabrication and characterization of mechanically induced long period fiber gratings in polarization maintaining photonic crystal fiber (PM-PCF). A supercontinuum source in the range of 600nm - 1700nm is used. This source is generated using a micro-chip laser at 1064nm and a single mode fiber. A long-period grating is induced over 40mm long unjacketed PCF using a V-grooved aluminum plate. External pressure is gradually applied with a metal screw and a torque meter and a loss dip with resonance wavelength is observed. Low insertion losses are depicted from (1-3) dBm with a bandwidth of about 30nm and a loss dip around 15dBm. Sensitivity for this preliminary work is found at 27 dB/Lb. Several applications are potentially possible with the optimization of the transmission spectrum controlled by applied pressure.

Research nonlinear optical properties of the materials for the fabrication of opto-electronic devices have growth in the last years. Ionics liquids present nonlinear optical properties. In this work we present the results of nonlinear optical properties of four ionic liquids of 1-methylpyrrolidine family, analyzed using a z-scan technique. The results show the difference obtained using or not a chooper for measuring the nonlinearity and the photoinduced lens. Ionic liquids have a negative nonlinearity (self-defocusing) of thermal origin.

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 present an experimental study of light polarization on solid core microstructured optical fibers type (Large Mode Area) LMA-16, LMA-20 and LMA-25. These fibers were partially filled with one micron diameter polyethylene spheres or carbon nanotubes diluted in distilled H 2 O by capillarity. Polarization characterization was realized on these Photonic Crystal fibers with air filled holes and partially particle filled holes using a He-Ne 633nm central wavelength laser at 10mW. The achieved results were compared using graphical data of every test collected at different exposition dates where the fiber was exposed to particle sedimentation. Results depicted that short time sedimentation of these particles does not change the light polarization leaving from the fiber except for the phase of the beam. On the other hand, longer time particle exposition visibly changes the light phase measured at the end of the photonic crystal fiber with repeatable results.

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.

In this work an investigation into the viability of a dual gas sensor based on correlation spectroscopy using a single Fabry-Perot Interferometer (FPI) is presented. Here, based on sensor response simulations, it is demonstrated that the commonly considered undesirable effect due to multiple internal reflections of the FPI's mirror substrate can be used to increase the sensing capability of the system. Usually designers tend to minimize these reflections to improve the FPI transmission spectrum. However we let them to occur in order to used them as a part of the modulation system of the sensor which allows us to detect two gases simultaneously using a single FPI.

We propose a temperature sensor based on dispersion shifted long period fiber grating (LPFG) fabricated with the fattening method, using electric arc discharges from a commercial fusion splicer machine. The fattened LPFG are centered at 1524 and 1550 nm, respectively. A temperature characterization in terms of the transmitted spectrum is realized with a pumped Er+3 doped fiber as the light source. The less than 3 mm in length fattened LPFG reached a sensitivity of 72 pm/°C between a temperature range of (25-500°C). Temperature stability was observed among the temperature range of (25-200°C), result in agreement with our previous studies. From up to 200°C sensing is observed as temperature increases. To apply this LPFG as a temperature sensor, sensing was measured as voltage signal outputs with repeatable results. This sensor is a high temperature resistant device because non deterioration of its properties was observed, and can find useful applications when temperature stability may be needed or the sensing requirements are desirable.

Several designs of infrared absorption based gas detector use a Fabry-Perot Interferometer (FPI) to modulate the incident light. In these systems, generally the FPI's fringes are matched with very well defined rotational absorption lines of a target molecule such as CO2, CO, N2O, CH4, etc. In order to obtain modulation the cavity length of the FPI is scanned over one half of the reference wavelength. In this work, we present a simple analytical method based on the Fourier Transform that describes the performance of these systems. Using this method the optimal reflectivity and optical spacing of the FPI can be determined. Furthermore, the modulated signal generated by the system as a function of the cavity length scan can be calculated by applying the inverse Fourier Transform. Finally, this method describes the underlying reasons why for some filters the background amplitude is severe, and gives guidance on the choice of optimised filters. Our method evaluates the optimal FPI parameters and the modulated signal much faster than the direct numerical computation which is used currently. Simulation results for different molecules in combination with diverse filters shapes are presented, with a comparison to directly computed results.

There are many sources of possible errors in phase shifting algorithms. One of those errors that may greatly influence the results is the detuning of the sampling points. Here we will describe a procedure to make the frequency interval in which the detuning error is smaller than a certain tolerances, as large as possible.

Most of the optics measurements techniques used generate interferograms as a result. These give us information about the object's quality, surface, etc. Evaluating and knowing the heat gradient of an object, is a typical application of the interferograms analysis. We know that if we subject an object to heat, this will generate interferograms, in which the fringes form will be temporal, the deformation of the fringes tel us the temperature gradient, but it doesn't give us the temperature level of the object. In order to obtain this level we sampled interferograms in different intervals and we count the number of fringes in every sample interferogram. With this process we make a characterization that provide the temperature level change in an object. In order to acquire the interferograms we used the National Instruments IMAQ-1408 board and the software was designed in LabView.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.