Active material for fiber core made by powder-in-tube method: subsequent homogenization by means of stack-and-draw technique

Rare-earth-doped optical fibres are widely used in lasers and amplifiers. The incorporation of ytterbium and aluminium oxide in a high doping concentration has led to the fabrication of a multi-mode (MM) optical fibre. Within this research, the design, preparation and calculation for the production of a fibre with a targeted 45 μm core diameter are explored. By Energy Dispersive X-ray (EDX) analysis, the doping concentrations of the elements in the core have been measured as 60.4 at.% Al and 1 at.% Yb. Supporting micrographs are used for confirming the core/cladding ratio. Based on the atomic percentage concentration, the calculated refractive index of the multi-element core has an n = 1.61 and an NA = 0.678. Characterisation of the fibre, including absorption and emission cross-section analysis, was performed in order to prove the ability of the fibre to be used for amplification as well as lasing applications.

Section: Refractive Indexcontrasting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multimode Ytterbium–Aluminosilicate Core Optical Fibre for Amplification and Laser Applications

Blaser,

Hänzi,

Pilz

et al. 2023

“…However, here we present our recent results ("Homogeneity" in Section 3.1.3) that this iterative melting and milling process it no longer needed to increase the homogeneity of the sol-gel-based granulated silica [7,8]. Another method used the stack-and-draw technique for homogenization [33] and reduced the scattering losses to values as low as 0.1 dB/m (measured at 1100 nm wavelength).…”

Section: The Granulated Silica Methodsmentioning

confidence: 94%

Granulated Silica Method for the Fiber Preform Production

Pilz

Najafi

Ryser

et al. 2017

During the past few years, we have studied the granulated silica method as a versatile and cost effective way of fiber preform production and the sol-gel method. Until now, we have used the sol-gel technology together with an iterative re-melting and milling step in order to produce rare earth or transition metal doped granular material for the granulated silica method. Here, we present that the iterative re-melting (laser-assisted) and milling step is no longer needed to reach a high homogeneity. The sol-gel method also offers a high degree of compositional flexibility with respect to dopants; it further facilitates achieving high concentrations, even in cases when several dopants are used. We employed optical active doped sol-gel derived granulate for the fiber core, whereas pure or index-raised granulated silica has been employed for the cladding. Based on the powder-in-tube technique, where silica glass tubes are appropriately filled with these granular materials, fibers has been directly drawn ("fiber rapid prototyping"), or eventually after an additional optional quality enhancing vitrification step. The powder-in-tube technique is also ideally suited for the preparation of microstructured optical fibers.

“…However, the efficient and practical way for evacuation from the top of the preform while drawing the fiber, as a result of using a coarse grain size, is lost. Another technique is homogenization by means of stack-and-draw [37]. This method yields very low scattering losses; however, the homogenization is achieved after several cycles of drawing-stacking-consolidation which can be very time consuming.…”

Section: Fiber Production Methodsmentioning

confidence: 99%

Fabrication and Characteristics of Yb-Doped Silica Fibers Produced by the Sol-Gel Based Granulated Silica Method

Sayed

Pilz

Najafi

et al. 2018

Combining the sol-gel method for fiber material production with the granulated silica method for preform assembly results in a robust method that offers a high degree of freedom regarding both the composition and the geometry of the produced fiber. Using this method, two types of Yb-doped silica glass composition, that feature an excess in P concentration with respect to Al, have been prepared. The elemental distributions in a fiber core were analyzed by scanning transmission electron microscopy (STEM). The elemental mapping shows a similar localization of Al, P and Yb through the microstructure. In addition, the influence of the variation in the co-dopant concentration, with respect to Yb, on the fiber properties has been investigated. The results show an increase in the refractive index step and in the fiber’s transmission loss as the excess concentration of P increases. A significant contribution to the losses can be assigned to the existence of impurities such as iron, which was detected in our samples by mass spectrometer. Single exponential fluorescence decays with lifetimes of around 0.88 ms were measured for the two compositions. Finally, pumping at 976 nm a laser slope efficiency of 67% at 1031 nm was achieved for one of the fiber compositions.