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Continuous-Wave Silica Fiber Lasers
Published in Johan Meyer, Justice Sompo, Suné von Solms, Fiber Lasers, 2022
Johan Meyer, Justice Sompo, Sune von Solms
The interest of using Erbium-doped fiber lasers results from its ability to obtain high gains around 1550 nm which corresponds to the third telecommunication window. However, outside of the telecommunication domain, that unique advantage of Erbium-doped glass fibers does not stand anymore. For fiber lasers emitting at wavelengths other than 1550 nm, other types of rare-earth ions are better candidates. One of the most used rare-earth elements (especially for high power fiber lasers applications) is the Ytterbium. With only two energy levels, namely the 2F7/2 ground level and the 2F5/2 excited level, Ytterbium possesses a simple energy levels structure compared to other rare-earth materials. Ytterbium can provide amplification from 975 nm to almost 1200 nm (Strohhöfer and Polman 2003). Also, Ytterbium-doped fiber lasers can exhibit higher output laser power and better conversion efficiency. Because of its energy levels structure, deleterious effects that affect Erbium-doped fibers like excited state absorption and clustering at high concentration are suppressed in Ytterbium, making it possible to increase doping concentration beyond value unacceptable for Erbium ions for example. Therefore, achieving a high gain in a relatively short length of fiber becomes possible. The other advantage of Ytterbium-doped fiber is its wide absorption band, hence, the possibility to use pump wavelengths covering a wide range. Figure 5.5 illustrates the energy level diagram of ytterbium with all possible transitions and their corresponding wavelengths.
Erbium-Doped Fibre Lasers
Published in Shyamal Bhadra, Ajoy Ghatak, Guided Wave Optics and Photonic Devices, 2017
Aditi Ghosh, Deepa Venkitesh, R. Vijaya
Amplifiers specifically based on EDFs, which have emission in the wavelength range suitable for communication, have been put to service in terrestrial systems since 1993. An exhaustive description of the fundamentals of such amplifiers can be found in Digonnet [13], Desurvire [14] and the references therein. Cascaded/multistage amplifiers can provide such high signal powers, but require extremely severe operating conditions [15]. Cladding-pumped amplifiers have also been increasingly used for generating high powers [16]. Co-doping EDFs with ytterbium is another emerging technology, which provides high signal powers [17]. However, for commercially deployed systems, standard core-pumped EDF amplifiers (EDFAs) continue to be the most sought-after technology. Ytterbium-doped amplifiers, on the other hand, find applications in material processing, spectroscopy and free-space communication.
In-situ approach for the synthesis of bromide-bridged mercury(II) N-heterocyclic carbene complexes
Published in Journal of Coordination Chemistry, 2020
Muhammad Atif, Haq Nawaz Bhatti, Muhammad Adnan Iqbal, Yasir Jamil
The present research was designed to synthesize halide-bridged mercury-NHC complexes for their possible use as stable transmetallation agents to obtain ytterbium-NHC complexes. Ytterbium complexes receive attention due to its exceptionally good magnetic properties as shown in ytterbocenes [19]. Ytterbium is very versatile in its applications as it is increasingly used in tunable lasers, catalysis of many chemical reactions, manufacturing high strength steel alloys, a source of radiation in place of X-rays, Yb-doped phosphorus for semiconducting applications, in ceramic capacitors, etc. [20–23]. There is growing trend to study the chemistry of ytterbium complexes in comparison to samarocenes and phosphines [24].