Juan M. Sierra-Hernandez

Laser Temperature Sensor Based on a Fiber Bragg Grating

In this letter, a temperature sensor based on a fiber ring laser is presented. A fiber Bragg grating was used as a sensor head, and a Mach-Zehnder interferometer (MZI) was utilized as a wavelength selective filter to enhance the temperature sensing capability. The MZI was achieved by splicing a piece of photonic crystal fiber between two segments of single-mode fiber. Moreover, it is shown that when the laser emission wavelength is shifted as the temperature is varied, achieving a temperature sensitivity of 18.8 pm/°C at 1550 nm, within the temperature range from 20 °C to 90 °C.

An All Fiber Intrinsic Fabry-Perot Interferometer Based on an Air-Microcavity

In this work an Intrinsic Fabry-Perot Interferometer (IFPI) based on an air-microcavity is presented. Here the air microcavity, with silica walls, is formed at a segment of a hollow core photonic crystal fiber (HCPCF), which is fusion spliced with a single mode fiber (SMF). Moreover, the spectral response of the IFPI is experimentally characterized and some results are provided. Finally, the viability to use the IFPI to implement a simple, compact size, and low cost refractive index sensor is briefly analyzed.

A tunable multi-wavelength laser based on a Mach?Zehnder interferometer with photonic crystal fiber

In this paper a tunable multi-wavelength erbium doped fiber laser, based on a Mach–Zehnder interferometer, is presented. Here the interferometer is achieved by splicing a piece of photonic crystal fiber (PCF) between two segments of a single-mode fiber. The laser can emit a single, double, triple or quadruple line, which can be tuned from 1530 to 1556 nm by controlling the polarization state. Finally it is shown, by experimental results, that the laser has high stability at room temperature.

A tunable multi-wavelength erbium doped fiber laser based on a Mach–Zehnder interferometer and photonic crystal fiber

In this paper a tunable multi-wavelength erbium doped fiber laser, based on a Mach–Zehnder interferometer, is presented. The interferometer is achieved by splicing a piece of photonic crystal fiber between two segments of a single-mode fiber. Here, by changing the curvature radius in the Mach–Zehnder interferometer, the single-, double- or triple-line emissions can be tuned from 1526 to 1550 nm. Finally it is shown, via experimental results, that the laser has high stability at room temperature.

A Core-Offset Mach Zehnder Interferometer Based on A Non-Zero Dispersion-Shifted Fiber and Its Torsion Sensing Application

In this paper, an all-fiber Mach-Zehnder interferometer (MZI) based on a non-zero dispersion-shifted fiber (NZ-DSF) is presented. The MZI was implemented by core-offset fusion splicing one section of a NZ-DSF fiber between two pieces of single mode fibers (SMFs). Here, the NZ-DSF core and cladding were used as the arms of the MZI, while the core-offset sections acted as optical fiber couplers. Thus, a MZI interference spectrum with a fringe contrast (FC) of about 20 dB was observed. Moreover, its response spectrum was experimentally characterized to the torsion parameter and a sensitivity of 0.070 nm/° was achieved. Finally, these MZIs can be implemented in a compact size and low cost.

Modified All-Fiber Fabry–Perot Interferometer and Its Refractive Index, Load, and Temperature Analyses

An all-fiber Fabry-Perot (FP) interferometer is proposed and validated by the arc splicing technique. By using conventional fiber and special hollow-core photonic crystal fiber, several FP cavities were formed at the conventional fiber tip using arc discharges. As a result of the interaction between these cavities, modified FP principle operation was obtained; and temperature, refractive index, and load analyses validated this operation modification. In addition, this all-fiber interferometer presents good resolution and sensitivity in each parameter examined. The structure offers compactness, robustness, high repeatability, and stability measurement.

A multi-wavelength erbium-doped fiber ring laser using an intrinsic Fabry–Perot interferometer

In this experimental paper, a multi-wavelength erbium-doped ring fiber laser based on an all fiber intrinsic Fabry–Perot interferometer is presented and demonstrated. The interferometer was fabricated by an arc and splicing technique using hollow core photonic crystal fiber (HCPCF) and conventional single mode fiber (SMF28). The fiber laser can be operated in single, dual and triple lasing mode by applying a transversal load over the all fiber interferometer. The laser spectrums present minimal mode spacing of 1 nm, high wavelength stability and power fluctuations around 0.5 dB. The average signal to noise ratio (SNR) of the laser emissions spectrum is around 35 dB. This fiber laser offers low cost, compactness and high wavelength stability.

Fast Parabola Detection Using Estimation of Distribution Algorithms

This paper presents a new method based on Estimation of Distribution Algorithms (EDAs) to detect parabolic shapes in synthetic and medical images. The method computes a virtual parabola using three random boundary pixels to calculate the constant values of the generic parabola equation. The resulting parabola is evaluated by matching it with the parabolic shape in the input image by using the Hadamard product as fitness function. This proposed method is evaluated in terms of computational time and compared with two implementations of the generalized Hough transform and RANSAC method for parabola detection. Experimental results show that the proposed method outperforms the comparative methods in terms of execution time about 93.61% on synthetic images and 89% on retinal fundus and human plantar arch images. In addition, experimental results have also shown that the proposed method can be highly suitable for different medical applications.

Ytterbium Fiber Laser Based on a Three Beam Optical Path Mach–Zehnder Interferometer

In this letter, a switchable ytterbium doped double cladding photonic crystal fiber (Yb-doped-DCPCF) laser based on a three optical path Mach-Zehnder interferometer (MZI) is presented. Here, the MZI with three-beam path was achieved by fusion splicing a segment of an Yb-doped-DCPCF between two pieces of single mode fibers. Moreover, in the proposed laser arrangement, the Yb-doped-DCPCF segment is acting simultaneously as the MZI and also as the gain medium. This laser can be switched to emit a single or double line by controlling the polarization state and it operates within the range from 1028 to 1033 nm. In addition, the laser emission has a linewidth of 0.07 nm and a single-mode suppression ratio of 40 dB. Finally, it is shown that the fiber laser arrangement is compact and robust and that requires a relativity simple fabrication procedure.

Determination of magnetic field using a Fabry–Perot cavity containing novel nanoparticles

ABSTRACT Mn0.75Zn0.25Fe2O4 nanoparticles were used to characterize magnetic fields using an all-fiber Fabry–Perot interferometer. The 20-nm nanoparticles were fabricated with citrate and displayed a coercive field of approximately 10 mT. The nanoparticles were dispersed in oleic acid to prepare a magnetic fluid to fill a Fabry–Perot structure fabricated by arc splicing with conventional single-mode and hollow core photonic crystal fibers. This device provided sensitivity and resolution of 0.11 dB/mT and 0.09 mT, respectively. Thermal analysis indicated that the magnetic measurements are weakly depending on temperature (0.7 pm/°C and 7 × 10−3 dB/°C). This device offers low-cost fabrication, simple implementation and may be used in several industrial applications.