Bismuth has attracted much attention because of its broadband near-infrared luminescence and it has also exhibited great potentials in optical communication and system laser technology. Bismuth element exhibits excellent properties in Bismuth element exhibits excellent properties in porous glass based on phase separation technology glass based on phase separation technology. In this paper, we investigate the dependence of Bismuth Active Center (BAC) on Na element in nanoporous glass. Based on phase separation technology, we prepared Bi doped nanoporous glass with different acid leaching times. An increase in the number of acid leaching cycles can reduce the content of Na elements in the glass by 96 wt%, effectively enhancing the luminescence intensity of BAC-Si and BAC-Ge, and causing their peak to blue-shift. Na ions are more likely to capture the electrons of oxygen ions in the glass, thereby weakening the electron supply of oxygen ions to Bi ions. This article lays a solid foundation for the study of Bi-doped nanoporous glass.
The nanoporous silica with silica content more than 96% can be obtained, which based on the glass phase separation technology, the boron rich phase can be removed by acid leaching which according to control the stable and uniform phase separation of borosilicate glass (SiO2-B2O3-Na2O). The porous glass has strong adsorption capacity and large surface area, in particular, the abundant broken bonds on the surface of porous glass channels provide enough non-bridging oxygen bonds. So that a new active fiber with high gain and uniformity can be obtained by drawing the rare earth doped nanoporous glass which is potential for fiber amplifiers and fiber lasers. However, nanoporous glass is doped in solution, hydroxyl groups will be retained after the sintering, which will increase the background loss of the material. Because Si-F bond energy is greater and bonding is stronger than Si-OH, F-bonds with Si replaced OH- by fluoride doping so as to reduce the loss caused by hydroxyl. In this paper, nanoporous glass is soaked in the solution with a certain concentration of fluoride, and sintered it at high temperature in helium atmosphere to reduce loss. The experimental results show that the hydroxyl content in porous glass gradually decreases with the increase of fluoride concentration, the raman peak at 935 cm-1 in the raman spectrum also confirms the existence of Si-F bond, and the lowest hydroxyl content is only 3.31ppm. In this case, the refractive index of glass will decrease uniformly with the increase of fluoride doping concentration, which provides a new method for preparing low loss nanoporous glass fiber materials.
Broad-spectrum light sources are widely used in optical fiber sensing and spectral analysis. At present, the supercontinuum spectrum generated by photonic crystal fiber nonlinearity covers a wide range of wavelengths, while it is a challenge to make the spectral flat, especially in 1000-1200nm range. In comparison, ultra-broadband light sources generated by doped fibers have better flatness. Bi-doped glass and optical fibers have attracted much attention in the field of ultra-broadband light sources and optical amplifiers due to their ultra-broadband spontaneous emission. We prepared Bi-doped quartz glass by glass phase separation method, and synthesized Bi active center-Al (BAC-Al) in glass by controlling the valence state of Bi by sintering atmosphere, which possess luminescence at 1120nm. Yb and Bi were simultaneously incorporated into glass for achieving combined BAC-Al and Yb luminescence. The combined spectrum covers 1000-1250nm, and the half maximum full width can reach 150nm. Various properties of the glass are tested, and the luminescence of bismuth and ytterbium in the glass are studied. The energy transfer between Bi and Yb was discovered, which can help to infer the energy level of BAC-Al. This work not only provides new materials and methods for ultra-broadband light sources, but also provides new ideas for exploring the near-infrared luminescence principle of Bi.
The Pharaoh's snake experiment has been handed down for thousands of years, bringing a lot of Oriental mysteries. Its key technology is to establish a porous structure with expanded volume. Here, the Pharaoh's snake techniques have been used for producing rare earth-doped glass. The high-sodium precursor composed of SiO2-Na2CO3-P2O5-Er2O3 is prepared by the water-cooling method,which exhibits the phenomenon of Pharaoh's snake at 300℃ and forms fluffy Er-doped glass-sooting. Then the glass-sooting is crushed and further mixed with SiO2 thoroughly, and melted at high temperature to obtain a transparent Er-doped sodium silicate glass. There are abundant non-bridging oxygen in the high-sodium precursor, which can dissolve more rare earth elements, while the Er-doped sodium silicate glass has high silica content, strong chemical stability, and high practical value. The Er atoms in the raw material made by mixing glass-sooting and silica are physically uniformly distributed, which can reduce the Er atom clusters caused by the slow diffusion of ions in the high viscosity of the glass liquid during the melting process. Under the excitation of 980nm laser, Er-doped sodium silicate glass emits narrow bandwidth fluorescence at 1.5um, which has a good application prospect in L-band fiber amplifiers.
KEYWORDS: Oscillators, Fiber lasers, Cladding, High power lasers, Diodes, Ytterbium, Fabrication, Doping, Laser damage threshold, High power fiber lasers
In this work, deuterium loaded Yb-doped fiber has been proposed to mitigate mode instability in laser oscillator. Experimental results reveal that mode instability threshold power rises from ~459W to ~533W and ~622W at the condition of pristine fiber and fiber loaded with deuterium for 2 weeks and 4 weeks respectively. Mode instability threshold power is raised by more than 16% and 35% after 2 and 4 weeks deuterium loading compared to pristine fiber respectively, and laser slope efficiency is not affected by deuterium loading. The experimental results indicate that deuterium loading is effective in mode instability mitigation and showing potentials in further power scaling of high power fiber lasers.
This work demonstrates the synthesis of indium tin oxide nanocrystals (ITO NCs) in mesoporous silica glasses (MSG) via the impregnation and decomposition method. The original MSG have many uniformly distributed mesopores (5-40 nm) which can regulate and control the size and distribution of ITO NCs. Factors that affect the properties of ITO NCs including temperature and holding time have been mainly studied. Interestingly, the enhanced down-conversion fluorescence intensity of Er3+/Yb3+ ions due to the energy transfer from ITO NCs has also been observed. Our work can widen the applications of semiconductor oxides in optoelectronics with a facile way.
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