Raman spectroscopy has been considered like a potentially important clinical tool for real-time diagnosis of disease and evaluation of living tissue, whit the proposal to development noninvasive glucose measurements in a near future, with lower power than other reported studies, in this work are reported experimental tests made with a excitation source of semiconductor laser of 785 nm and 35 mW power.<p> </p> Measurements were made to different glucose concentrations, with variation from 50 mg/dL to 6000 mg/dL. For this, three intervals with different ranges of concentration were analyzed, these tests were put into plastic sampling cells, making incise the beam vertically on sample. In the same way measurements to serum human are reported, for healthy volunteers had 12 hours fasting and non-fasting conditions, with it's corresponding values of glucose taken through a conventional glucometer.<p> </p> Freeze-dried human serum was poured on object-holder, in the case of human serum reconstitute, it was used container in which were previously kept samples. Nine spectra per test were obtained and subsequently average was calculated, the spectra were studied in a range of 500 to 1700 cm<sup>-1</sup>. This work explores the intensity variation of the bands of glucose in 1065 cm<sup>-1</sup> and 1127 cm<sup>-1</sup> as a function of glucose concentration. In the obtained results, there observes a behavior with positive slope in both substances, interrelation being observed between the measurements, being promissory for non-invasive measurement.
An optical fiber trap operates by radiation pressure and transverse force gradient while conventional optical trap operates on longitudinal gradient to trap particles. This subtle difference translates into easy setup and many advantages over conventional single-beam optical tweezers. In this work, we present a brief review of the current situation of fiber optic trap and their applications. Subsequently, we discuss the effect of radiation pressure on micro-organic and inorganic particles. Using a single optical fiber, radiation pressure transfers movement to the micro-particles, so velocity and acceleration are quantified. After that, micro particles are trapped, but now using two optical fibers. Finally, we discuss the results and problems involved with this research.
Heat pumps work with a refrigerant mixture of lithium bromide-water (LiBr-H<sub>2</sub>O) and the efficiency of the heat pump
may be adjusted depending on the concentration of this mixture. On the basis of the last, in this work an analysis of LiBr
concentration by multimode interference (MMI) effects occurring in a single-mode-multimode-single-mode (SMS) fiber
structure is presented. In the SMS structure the sensitive element consists in a multimode fiber (MMF) section spliced
between two single-mode fibers (SMF) in order to launch light into and recover light from that multimode waveguide.
The multimode fiber (MMF) has no cladding so that its exposed core interacts with different concentrations of LiBr-H<sub>2</sub>O
which refraction indices are between 1.423 and 1.472. The different refraction indices of the solution covering the
exposed core generate variations in the modes coupling inside the multimode section of the SMS fiber, and therefore, a
different response for each case. SMS fiber structure was designed to generate a first self-image of the input profile at a
1555 nm wavelength. The experimental set up consists of a laser diode operating at 1550 nm as the source of the system,
a photodetector as the transducer of the transmitted intensity and a digital multimeter.
Applications of Multimode Interference (MMI) effects in optical devices have been increased today due their excellent
properties and easy fabrication. Incorporation of these effects in optical fiber has been achieved through a single-mode -
multimode - single-mode (SMS) fiber structure showing high sensitivity to bending-loss phenomenon. The latter has
been efficiently implemented in pressure sensing application such as is presented in this work. Basically, the SMS
structure is embedded in a pressure-sensitive membrane to convert pressure in a mechanical displacement resulting in an
attenuation of the transmitted intensity proportionally to the applied pressure. Under this configuration, an all-fiber
pressure sensor with high sensitivity and repeatability is obtained into a pressure range from -13 psi to +13 psi. The max
pressure range can be varied to 140 psi with our configuration when the membrane thickness is changed. Important
features of the proposed all-fiber MMI pressure sensor are its easy-fabrication and low-cost since an inexpensive
instrumentation is required.
A comparative analysis of ultraviolet light absorption is presented for distinct photosensitive optical fibers. Fibers are
irradiated by ultraviolet light, coming from a pulsed Nd:YAG Laser (90 mJ, 5-7 ns) at 266 nm. Absorption is analyzed
from ultraviolet to infrared region and it is compared for different photosensitive optical fibers. The final goal of this
work is to identify absorption spectral regions, which would be useful in order to improve fiber grating printing.
Waveguides coupling have been widely studied; however, nanowaveguides of high refraction index contrast open the
opportunity of studying the nonlinear dynamics of coupled waveguides, in particular those filled with metallic
nanaoparticles composites. Those composites show a Quantum Mechanical Kerr Nonlinearity and a classical field
amplitude nonlinearity that are compared by using a iterative WKB to introduce the field nonlinearity and based in the
ensuing M matrix. The produced nonlinear supermodes show a confinement of the pulse in the waveguides and a
breaking of the coupling at small and large core waveguides.
We report on a novel all-fiber refractometer sensor based on multimode interference (MMI) effects. The operating
mechanism is based on the self-imaging phenomena that occur in the multimode fiber (MMF) section, which basically
replicates the field at the input of the MMF on the output of the MMF for a specific wavelength. However, the
longitudinal position of this image is highly dependent on the MMF diameter (D), since there is D<sup>2</sup> dependence on the
longitudinal position of this image. For the refractive index measurement a section of no-core multimode fiber, whose
cladding is air, is surrounded by the liquid sample. The liquid sample now works as the cladding medium and as a result
of the Goes-Hanchen shift the effective width (fundamental mode width) of the No-Core fiber is increased. As a result,
the maximum coupling resulting from the imaging phenomena occurs at a different wavelength, and this can be used to
measure the refractive index of the liquid. Using this scheme we can achieve a resolution on the order of 1x10<sup>-5</sup> for a
refractive index range from 1.333 to 1.434. The device was used here to measure refractive index in liquids, but can also
be applied for measuring concentration of liquids. These sensors are promising and attractive in chemical and
biotechnological applications because of their high sensitivity, immunity to electromagnetic interference, and compact
The study of nonlinear photonics crystals is quite complex and cumbersome, because of their inherent architectural complexity and, in addition, because of the nonlinearity that couples propagating and counterpropagating waves. However, they are quite attractive because of their potential capabilities, and that has lead to use different approximated methods. In a one dimensional stack, it has been successfully demonstrated that they show switching, bistability and chirping as nonlinear characteristics. Band gap solitons are a well established feature of the coupled wave equations. We have extended a method that have previously shown its success for a stack with a Kerr nonlinearity, to a much more complex structure such as an omniguide fiber, as part of our suggestion that such method could be applied to numerical or analytical methods as long as the linear solution were available. Such a restriction, hinder our ability of
getting analytical solution beyond their enabling approximations, however, it is completely adequate for the purpose of to develop devices. A comparative numerical analysis of a one dimensional photonic crystal and an omniguide fiber, made of a dielectric
and stratified linear and nonlinear media, has been carried out. They were considered as multilayer arrangements with a finite numbers of periods: linear-linear, nonlinear-linear and nonlinear- nonlinear in order to study and isolate those features. Finally, a comparison of multilayer systems with variations in the diffraction indexes profiles is presented.
We report on a new type of cladding-pumped neodymium-doped fiber which enables strong ASE emission at the wavelength region of 940 nm with a highly reduced emission in the four-level transition at 1060 nm when is pumped by an 806 nm source. This ASE source delivers a total emission power of 60 <i>mW</i> from 500 mW of absorbed pump power. The arrangement setup consisted in a pump diode emitting at 806 nm with a total output power of 1.5 W, a collimated and focused lenses and a dichroic mirror. The broadband of the neodymium source was measured to be 25 nm. Moreover, a numerical simulation for the ASE source is also discussed.
An analysis of out-coupling in a laser shows an optimum way of subtracting more output power by choosing an appropriate cavity arrangement from a high-power fiber laser. This investigation consisted in resolving analytically the effect of different cavities in our laser system and one thing that outcome was to know that a fiber laser can operate with high efficiency even with high losses in one end of the cavity (e.g. at an external diffraction grating), only if the feedback in the out-coupling end is low. Moreover, it was also found that is possible to improve the output power by reducing the feedback in the out-coupling end. Parameters considered in this resolved method are 0.1 NA, 10 μm diameter core, 200 μm inner-cladding diameter and 10 dB small-signal absorption. The fiber laser was doped with ytterbium and lases at 1080 nm, when pumped at 915 hm. The maximum pump power was set to 10 W.
In this work, the deposit technique of amorphous films for production of optical waveguides is presented, as well as the characterization of these waveguides. The basic theory is also presented for propagation of light in waveguides.
We provide an analysis of a data beam fitting method of <i>N</i> data points on a circular pupil that corresponds to its
best rms fit that uses an orthogonal vectorial basis of the <i>N</i> data points. The solutions of many physical problems often result on finding specific solutions of basic functions <i>F<sub>nl</sub></i>(ρ,θ) with polar symmetries that also can be easily treated numerically. Unfortunately, in some other cases, the analytical
solution loss its orthogonality by the experimental data discretization, therefore become inadequate for a best rms fit
data. On the other hand, by introducing the Schmidt orthogonalization, we can get the best rms fit for the solution in the coefficients of the expansion and in <i>F<sub>nl</sub></i>(ρ,θ). In these cases, where the <i>F<sub>nl</sub></i>(ρ,θ) has a cumbersome convergence, we develop the rms fit based on Zernike like Polynomials and establish the proper transformation. We illustrate in more detail the method by developing a beam analyzer as an application.
We have experienced an Associated Degree on Engineering and a subsequent Bs on Electronic Engineering that uses Optics as the essential introduction to Modern Ondulatory Physics. This first experience in Mexico is important because the popular origin of Mexican Engineering Students, that represents the 27% of the National enrollment.
In this work we discuss the possibility of using an optical fiber laser constructed by two Bragg grating as a temperature sensor. The device is based on measurement of the power transmitted through the Bragg gratings when the temperature of one of these gratings is changed. Changes on the temperature results in a shift of reflection wavelength of the Bragg grating and therefore change the transition coefficient. The resulting change of the power at the laser output can be used for simple and exact measurement of the temperature.
Recent developments in the construction of Erbium-doped fibers have seen parallel progress in the measurement techniques to characterize these fibers. In this paper, we discuss a simple method of obtaining threshold power amplification of Erbium-doped fibers. The method can be used to measure the threshold power of this particular fiber. As a result, the predicted threshold power value is in very good agreement with the experimental results obtained. We have based our measurements of the amplified spontaneous emission on both the forward and the backward directions of the fiber axis. We also report on other parameters such as Erbium doping concentration, the spectrum of absorption, and cross sections, with the objective of obtaining data for comparison of predicted threshold amplification with actual threshold amplification, when the Erbium-doped fibers are used in laser systems.