Daniel Toral-Acosta

High Sensitivity Fiber Laser Temperature Sensor

This paper presents an erbium-doped fiber laser temperature sensor, which is based on an intracavity fiber filter immersed in glycerol/water solutions. The sensing element is the intracavity fiber filter, consisting of a two-taper fiber Mach-Zehnder interferometer (MZFI). The high refractive index dispersion of glycerol/water solutions with temperature allowed the modification of the MZFI spectral characteristics and hence determines the lasing wavelength. The sensitivity of 1089 pm/°C and a signal-to-noise ratio of 50 dB make the proposed sensor suitable for real applications.

Self-pulsing in a large mode area, end-pumped, double-clad ytterbium-doped fiber laser

The characteristics of self-pulsing in a large mode area, end-pumped, double-clad Yb-doped fiber laser are presented. The laser operates in a self-pulsing regime, either by using one or two perpendicularly cleaved ends as the feedback mirrors, while it transforms in a broadband amplified spontaneous emission source when both ends are angle cleaved. In the pulsed regime, up to 2 µs full width at half maximum pulse widths and repetition rates of the order of hundreds of kHz are generated.

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.

Noncontact Optical Fiber Sensor for Measuring the Refractive Index of Liquids

A noncontact optical fiber sensor for measuring the refractive index of transparent liquids is proposed. It operates by calculating the path of a focused laser beam at 635 nm that travels across the boundaries of a liquid sample. The optical power Fresnel reflections are detected and, subsequently, the refractive index is determined as the ratio between the traveled beam paths when the liquid is deposited versus a reference without the liquid sample. Additionally, a mathematical analysis of the geometrical case is included. The theoretical data from our sensor are in good agreement with the experimental results. The resolution achieved by the sensor is better than 10−3 RIU.

Torsion sensor using a Mach-Zehnder interferometer

A novel torsion sensor based on a Mach-Zehnder interferometer is presented. The interferometer is made with a piece of Ytterbium doped photonic crystal fiber (YbDPCF) spliced between two single-mode fibers. The torsion sensitivity obtained is 0.05nm/º in a torsion range from 0° to 360° along with a sensitivity of 0.06dBm/º at specific wavelength. The interference fringes and torsion characteristics have been experimentally investigated and demonstrated. This compact fiber component with acceptable sensing performance makes its a good candidate for the measurement of numerous physical parameters.

Post-shaping optical fiber taper filters

Geometrical shaping of non-adiabatic single tapers is used to modify the filtering characteristics. The fiber tapers are shaped by successive tapering. The taper shaping produces deeper rejection bands. As an application of the shaped tapers, fluidic temperature sensing cells were fabricated. In a first case, the wavelength shift of a single rejection band was monitored, showing a nonlinear response and low sensitivity to temperature changes. In a second case, a shaped taper fluidic cell containing two rejection bands was used, and the wavelength shift of the half intensity points of the transmission band (between the rejection bands) was taken as a measure of the temperature change. In this case, the fluidic cell showed a linear sensitivity of 481.9 pm/°C in a temperature range of 25°C-60°C.