Hector H. Cerecedo-Nunez

Optical time-domain reflectometry interrogation of multiplexing low-reflectance Bragg-grating-based sensor system

Low-reflectance fiber Bragg gratings (FBGs) can be interro- gated in real time with a high-resolution optical time-domain reflectom- etry (OTDR) technology. The technique allows interrogation of a series of FBGs with the intensity change based on the OTDR pulse spectral char- acteristics and the FBG reflection. Experimental results are presented for multiplexing of dual-wavelength FBG sensors to produce referencing calibration in sensor measurement. With this structure, the influence of the source power fluctuations and fiber bend losses can be greatly re- duced. This scheme can be applied to the practical measurement of distributed temperature or strain.

The ellipse in parabolic motion: An undergraduate experiment

We present a simple method of experimentally studying the elliptic shape of the joined apices of parabolic projectile trajectories in the undergraduate laboratory. The experimental data agrees well with theoretical results, and we find that this experiment provides an interesting twist to the venerable undergraduate experiment on projectile motion.

Analysis of polarization states in an optical fiber under magnetic field effects

We show simulated results about changes of the polarization states from a beam of light in an optical fiber, when we introduce a magnetic field in one section of the fiber. The model includes controllable parameters such as, the current applied to a reel (magnetic field), the birefringence, the incident angle of the light and the magnetic field into the fiber. The theory, simulations and experimental verification of this problem are discussed.

Transforming the canonical piecewise-linear model into a smooth-piecewise representation

A smoothed representation (based on natural exponential and logarithmic functions) for the canonical piecewise-linear model, is presented. The result is a completely differentiable formulation that exhibits interesting properties, like preserving the parameters of the original piecewise-linear model in such a way that they can be directly inherited to the smooth model in order to determine their parameters, the capability of controlling not only the smoothness grade, but also the approximation accuracy at specific breakpoint locations, a lower or equal overshooting for high order derivatives in comparison with other approaches, and the additional advantage of being expressed in a reduced mathematical form with only two types of inverse functions (logarithmic and exponential). By numerical simulation examples, this proposal is verified and well-illustrated.

Analysis of anhydrous glucose and human serum assisted by Raman spectroscopy

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. 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 its corresponding values of glucose taken through a conventional glucometer. 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-1. This work explores the intensity variation of the bands of glucose in 1065 cm-1 and 1127 cm-1 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.

ASE Noise Attenuation for Signal at 1548.4 nm Through a Sagnac Interferometer Using High-Birefringence Fiber Which Is Subjected to Temperature Changes

This paper reports the construction of an experimental setup to attenuate the ASE (Amplified Spontaneous Emission) noise around 1548.4 nm. A Sagnac Interferometer (SI) which uses high-birefringence fiber (Hi-Bi fiber) at 8, 22 and 110 cm is used as band pass filter for attenuating the ASE noise. Temperature variations are made to tune in the filter SI. A test signal containing noise ASE is taken from an erbium-doped optical fiber and a fiber Bragg grating (FBG), therefore the 1548.4 nm signal surrounded for ASE is obtained. This test signal is introduced into the SI filter and the transmitted power of the interferometer is measured, the transmitted signal of SI has periodic variations with maximums and minimums, the SI is tuned in with temperature to bring the maximum transmitted power at the same wavelength of the signal 1548.4 nm. We found experimentally that is possible to attenuate the ASE noise contribution around 1548.4 nm by comparing the input test signal versus the output signal at the output port of SI. In addition, we found the displacement of the transmittance with respect to temperature (Δλ/ΔT) and the period of the transmitted power (Δλ).

Comparative Analysis of Optoelectronic Properties of Glucose for Non-invasive Monitoring

Among the diversity of methods for glucose level monitoring in human blood, invasive techniques are still the most commonly used. Blood samples, usually obtained with finger-pricking devices, are analysed through enzymatic reactions via electrochemical or photometric principles. In this paper, non-invasive methods for blood glucose monitoring are studied and compared, while also analysing optical and electronic properties of glucose. From this comparative analysis, proposals are made towards the design and characterisation of novel devices capable of monitoring blood-glucose levels through optoelectronic non-invasive procedures. Alteration of electrical parameters of cellular membrane, such as electric permittivity and conductivity as a function of blood glucose concentration, are observed and compared to the responses to optical stimuli. The investigation is developed by establishing a correlation between the effects of diffusion and dispersion of light on the concentration and dispersity of blood particles, and the response of electrical parameters under different glucose concentrations. As a result of the analysis, recommendations are made for the most suitable parameters and instrumental methodology, in terms of feasibility, easiness and precision, for non-invasive monitoring of blood glucose levels.

Microbubble Generation with Tapered Optical Fiber

We present the microbubble generation using tapered optical fibers. We studied the relation of microbubble generation with experimental parameters. We report the relation of these, with size, speed of growing and lifetime of the microbubbles.

Erratum: “The ellipse in parabolic motion: An undergraduate experiment” [Am. J. Phys. 82, 354–356 (2014)]

M. A. Carrillo-Bernal, P. E. Mancera-Pina, H. H. Cerecedo-Nunez, P. Padilla-Sosa, H. N. Nunez-Yepez, and A.L. Salas-Brito Citation: American Journal of Physics 82, 707 (2014); doi: 10.1119/1.4874515 View online: http://dx.doi.org/10.1119/1.4874515 View Table of Contents: http://scitation.aip.org/content/aapt/journal/ajp/82/7?ver=pdfcov Published by the American Association of Physics Teachers Articles you may be interested in Erratum: “The torque on a dipole in uniform motion” [Am. J. Phys. 82, 251–254 (2014)] Am. J. Phys. 82, 354 (2014); 10.1119/1.4869186 The ellipse in parabolic motion: An undergraduate experiment Am. J. Phys. 82, 354 (2014); 10.1119/1.4864291 On the numerical solution of a two dimensional elliptic-parabolic equation AIP Conf. Proc. 1479, 606 (2012); 10.1063/1.4756205 Erratum: “On a fourth order degenerate parabolic equation in higher space dimension” [J. Math. Phys.50, 123524(2009)] J. Math. Phys. 53, 079901 (2012); 10.1063/1.4736991 Comment on “Diamagnetically stabilized magnetic levitation,” by M. D. Simon, L. O. Heflinger, and A. K. Geim[Am. J. Phys. 69, 702 (2001)] Am. J. Phys. 70, 188 (2002); 10.1119/1.1430699

Optical fiber trap: radiation pressure effect on inorganic and organic micro-particles

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.