15 research outputs found
Preparation and characterization of highly thulium- and alumina-doped optical fibers for single-frequency fiber lasers
Thulium-doped fibers suitable for core-pumped single-frequency lasers were
fabricated by the modified chemical vapor deposition (MCVD) method. Refractive
index profile, doping profile and spectral absorption was measured. High doping
concentration of thulium ions should be achieved to allow for high absorption
of light at a pump wavelength while the thulium ions clustering should be
avoided to prevent the cooperative upconversion and quenching processes. The
fabricated fibers featured pump absorption up to 70dB/m at a pump wavelength of
1611nm. The single-frequency master oscillator with a resonator composed of a
pair of fiber Bragg gratings and a thulium-doped fiber was demonstrated with
predominantly single ended operation. We achieved a slope efficiency of 22% and
a threshold of 22mW at a lasing wavelength of 1944nm
Theoretical analysis of fiber lasers emitting around 810 nm based on thulium-doped silica fibers with enhanced 3H4 level lifetime
International audienceWe investigate performance of compact thu- lium-doped fiber laser at 810 nm in three diffe- rent hosts: ZBLAN, standard silica and silica modified by high alumina codoping. We found that efficient lasing at 810 nm in silica should be possible for short ranges of fiber parameters, especially when 3H lifetime is enhanced
Preparation and Properties of Er-Doped ZrO2 Nanocrystalline Phase-Separated Preforms of Optical Fibers by MCVD Process
The fabrication of Er-doped ZrO2-based nanocrystalline phase-separated silica
optical preforms by the MCVD and solution doping techniques is presented.
Fabricated preform cores are nearly transparent and contain phase-separated
rare-earth doped nanocrystalline particles with diameters mainly in a range
from 20 to 80 nm. High concentrations of erbium and aluminium in preform cores
of about 0.3 and 14 mol%, respectively have been achieved without defects on
the core-cladding interface. Spectral losses in a range 800-1600 nm and
fluorescence spectra of erbium ions around 1550 nm measured on a fibre drawn
from the preform are reported
USING PVDF FILMS AS FLEXIBLE PIEZOELECTRIC GENERATORS FOR BIOMECHANICAL ENERGY HARVESTING
In this paper, a commercial polymeric piezoelectric film, the polyvinylidene fluoride (PVDF) was used to harvest electrical energy during the execution of five locomotion activities (walking, going down and up the stairs, jogging and running). The PVDF film transducer was placed into a tight suit in proximity of four body joints (shoulder, elbow, knee and ankle). The RMS values of the power output measured during the five activities were in the range 0.1 – 10 µW depending on the position of the film transducer on the body. This amount of electrical power allows increasing the operation time of wearable systems, and it may be used to prolong the monitoring of human vital signals for personalized health, wellness, and safety applications
Thulium-doped silica fibers with enhanced <sup>3</sup>H<sub>4</sub> level lifetime: modelling the devices for 800-820 nm band
Silica-based thulium-doped fiber devices operating around 810 nm would extend the spectral range covered by highpower fiber devices. Using a comprehensive numerical model of the fiber we have shown that efficient lasing at 810 nm can be achieved for specific ranges of the laser cavity parameters in silica-based thulium-doped fibers with enhanced 3H4 lifetime up to 58 µs as measured in our highly alumina-codoped fibers. We present optimization of the thulium-doped fiber and laser cavity parameters and also potential applications of the developed host material in amplifiers and broadband sources
Thulium-doped silica fibers with enhanced 3
International audienceSilica-based thulium-doped fiber devices operating around 810 nm would extend the spectral range covered by high- power fiber devices. Using a comprehensive numerical model of the fiber we have shown that efficient lasing at 810 nm can be achieved for specific ranges of the laser cavity parameters in silica-based thulium-doped fibers with enhanced 3H4 lifetime up to 58 μs as measured in our highly alumina-codoped fibers. We present optimization of the thulium-doped fiber and laser cavity parameters and also potential applications of the developed host material in amplifiers and broadband sources
Wideband and high-power light sources for in-line interferometric diagnostics of laser structur-ing systems
Laser structuring is rapidly developing manufacturing technique for broad spectrum of industrial branches, e.g. aerospace, power engineering, tool- and mould making, and automotive. It enables to prepare work pieces and products with very fine micro structures achieving a far better degree of details than conventional structuring techniques like etching or eroding. However, the state of art in laser structuring shows a crucial deficit. Used systems contain no metrology setup to detect the shape geometry (depth and length) and contour accuracy during the process. Therefore, an innovative in-line metrology technique based on low coherence interferometry for laser structuring systems has been investigated and described in the paper. In this contribution we present our results in the research of wideband and highpower light sources for the proposed low-coherence interferometric measurement system. The system can be incorporated into a structuring workplace equipped with a Q -switched ytterbium-doped fiber laser at 1064 nm for material processing. In the paper we focus on two wideband sources for such a measurement system. The first source is based on a superluminescent diode and the second one is based on an amplified spontaneous emission in a double-clad ytterbium-doped fiber. An example of results measured with the proposed in-line metrology system is presented
Using PVDF films as flexible piezoelectric generators for biomechanical energy harvesting
In this paper, a commercial polymeric piezoelectric film, the polyvinylidene fluoride (PVDF) was used to harvest electrical energy during the execution of five locomotion activities (walking, going down and up the stairs, jogging and running). The PVDF film transducer was placed into a tight suit in proximity of four body joints (shoulder, elbow, knee and ankle). The RMS values of the power output measured during the five activities were in the range 0.1-10 μW depending on the position of the film transducer on the body. This amount of electrical power allows increasing the operation time of wearable systems, and it may be used to prolong the monitoring of human vital signals for personalized health, wellness, and safety applications