The use of plastic optical fibers as sensors represents advantages due to the malleability of the material and the number of modulations it allows, in addition, it's a flexibility and low-cost material. Currently, optical couplers have also been developed in plastic fiber optics, due to their main use in telecommunications, and prices are increasingly affordable. In addition, the use of technologies in optics and photonics are more accepted in areas such as medicine, industry, beauty, sensors, and more. (1) In this work, a force sensor is achieved, based on beam modulation, made of a 2x2 (50:50) coupler of 1mm diameter Plastic Optical Fiber (POF), with a 10 cm POF joined to the output to generate a loop. This section was polished in D, V and cylindrical shapes, at 30% and 50% polished depth, using a visible spectrum, in 632.8 nm of an He-Ne laser source. The spectral response is obtained in a force range of 0-500 N which is gradually applied to the fiber polished section. A linear sensitivity of force-beam modulation is obtained.
In the present work, we show the results of theoretical calculations of nonlinear optical properties of choline chloride – urea deep eutectic solvent mixture. Deep eutectic solvents are a novel kind of solvents with similar properties to classic ionic liquids but with advantages like been easy to prepare and biodegradable. We had obtained the most stable structure using DFT optimization with M06-2X/6-311G(d,p). Then their static and dynamic (at 477 nm) first and second order hyperpolarizabilities were obtained. These results were used to estimate the third order nonlinear susceptibility showing that this solvent is promising for nonlinear optics-related application.
Claudia Angelica Rivera-Romero, Elvia Ruth Palacios-Hernández, Mónica Trejo-Durán, Maria del Carmen Rodríguez-Liñán, Roberto Olivera-Reyna, Jorge Alberto Morales-Saldaña
Cucurbits plants are very susceptible to fungal diseases as powdery mildew (PM) infection. Currently, the PM early detection in the field is the cutting-edge research. The objectives of our study were to assess visible and near-infrared spectroscopy of normal and infected leaves for early detection of PM in Cucurbita pepo L. plants. Samples for spectral analysis were taken three days a week (Monday, Wednesday, and Friday) after the first true leaves appeared. The reflectance spectra of leaves were collected using an HR4000CG-UV-NIR spectrometer (Ocean Optics) with a fiber optics probe. Vegetative indices were used for discrimination between infected and healthy plants. The calculated vegetation indices (green normalized difference vegetation index, triangular greenness index, single-band reflectance index, simple ratio indices, and anthocyanins reflectance index) showed the highest sensitivity to differentiate healthy, infected plants at a symptomless stage, first symptoms, and diseased plants. The best prediction on early detection in sampling days were structure-independent pigment index and red-edge reflection point with an R of 0.211 and 0.1893, respectively. Our study shows the efficacy of the identification based on reflectance spectra for an early distinction of PM disease and could be used in cucurbits plants with similar characteristics on leaves.
In this work we present the synthesis of Au@Ag bimetallic nanoparticles via seed-mediated method and their nonlinear optical properties. For the synthesis of nanoparticles, 18 nm gold seeds were synthesized by Turkevich method followed by the silver ion reduction with ascorbic acid. The nanoparticles dispersion was analyzed by UV-Vis spectroscopy and the spectra suggest the formation of spherical core@shell bimetallic nanoparticles. SEM images were obtained in order to corroborate this. The nanoparticles dispersions present negative and positive nonlinear absorption coefficient and negative refraction index, according to z-scan measurements. The nonlinear optical properties can be tailor modifying the thickness of shell.
Physical and optical characterization of thin films doped with Au Nanoparticles onto a silica substrate is presented. Films were prepared through sol-gel process, by using Au nanoparticles immersed in lipoic acid as dopant by means of hydrolysis and acid catalyzed reaction of tetraethyl-orthosilicate. The surface was characterized by SEM and AFM microscopies. Z-scan technique was used to measure nonlinear optical properties as nonlinear absorption and refraction indexes, using two different wavelengths. At 633 nm it was possible to observe nonlinear absorption only but at 514 nm both nonlinear properties were observed.
Characterization of thin films doped with organic metal materials onto a silica substrate is presented. Films were prepared through sol-gel process, by using macrocycles with Cu as dopant by means of hydrolysis and acid catalyzed reaction of tetraethylorthosilicate. Z-scan technique was used to measure nonlinear optical properties, nonlinear absorption and refraction indexes.
This paper presents the design and implementation of an optical sensor to detect color changes in fruit by means of white light reflection to measure fruit ripeness in industrial and agricultural applications. The system consists of a LED RGB array including photodetectors, a power source and plastic optic fiber (POF). By means of Labview ® graphic interface we can control the power emission of the diodes digitally mixing the colors at different intensities until we achieve white light to be used as a source for the color sensor. We used an ATmega2560 microcontroller as a data collection device to monitor the colors obtained and to show them as color models using Matlab ®. We show results from tests conducted using two guava samples, observing the evolution of the color change on the fruit skin until they became overripe.
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.
In this work, the fabrication of thin films mixed with cholesterol enzyme as recognition component is shown, using solgel technique. The film was deposited at one end of photonic crystal fiber (optrode), which was used as carrier medium of sol-gel matrix. The concentration of cholesterol in the test sample was determined by the use of transmittance. Measuring device consists of a power source (laser diode), optrode and a light detector. The laser beam is transmitted through the optrode; the variations of intensity depending on cholesterol concentration are emitted to be detected by a photoresistor.
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 of nonlinear optical properties of materials for manufacturing opto-electronic devices, had a great growth in the last years. The solutions with nanoparticle metals present nonlinear optical properties. In this work we present the results of characterizing, analyzing and determining the magnitude and sign of the nonlinear refractive index, using the z-scan technique in solutions with nanoparticles of gold, lipoic acid and sodium chloride. We used a continuous Argon laser at 514 nm with variable power, an 18 cms lens, and a chopper. We determined the nonlinear refractive index in the order of 10-9. These materials have potential applications mainly as optical limiters.
In this work we present the study of nonlinear optical properties of Au nanoparticles suspended in different solutions, using the z-scan technique. Thermal lens model and Shiek-Bahae formalism were used to determine the nonlinear properties. Parameters as the sign and nonlinear refractive index n2 , nonlinear absorption coefficient (β) and dn/dt were found. Analyses of changes in these parameters using different solutions with the same concentration of Au nanoparticles are shown.
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.
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.
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 a new method for mass production of the photonic crystal devices on the basis of widely-known and well-developed technology such as micristructured optical fibers. In this paper, we investigate the optical properties of side-excited microstructured fiber and discuss the conditions for utilization such a structure as planar photonic crystal device, namely, the high-quality resonance filter.
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.
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.
In this work, we show results about the nonlinear optical characterization for four ionic liquids (ILs), namely 1-buthyl-3-
methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-ethyl-3-methylimidazolium Bis((trifluoromethyl)sulfonyl)imide
([EMIM][TF2N]), 1-ethyl-3-methylimidazolium trifluoroacetate ([EMIM][CF3COO]),1-buthyl-3-methylimidazolium
trifluoroacetate ([BMIM][CF3COO]), using z-scan technique.
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 probe. 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 and 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 7 and 10.5. Such signal is captured by a photodetector and processed with a LabView development environment which also controls a hardware designed in our laboratory. The advantage of this system is that 2cm of doped fiber are enough to measure the pH of a fluid in real time. The response time of this system is approximately 10s.
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.
We present the control of the monochromator DK240 developed by a program in LabVIEW, this program adjusts the entrance/exit slits, the scan of the measurement of the wavelength in a range from 100 nm to 3000 nm as well as the scan speed, we also show experimental setup to measure the absorption of Erbium-Doped Fiber and its experimental graph.
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.
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
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.