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Simulation of optical fiber amplifier gain using equivalent short fibers
摘要： Electromagnetic wave propagation in optical fiber amplifiers obeys Maxwell equations. Using coupled mode theory, the full Maxwell system within an optical fiber amplifier is reduced to a simpler model. The simpler model is made more efficient through a new scale model, referred to as an equivalent short fiber, which captures some of the essential characteristics of a longer fiber. The equivalent short fiber can be viewed as a fiber made using artificial (unphysical) material properties that in some sense compensates for its reduced length. The computations can be accelerated by a factor approximately equal to the ratio of the original length to the reduced length of the equivalent fiber. Computations using models of two commercially available fibers – one doped with ytterbium, and the other with thulium – show the practical utility of the concept. Extensive numerical studies are conducted to assess when the equivalent short fiber model is useful and when it is not.
关键词： Scale model,Ytterbium,Thulium,Laser gain,Fiber amplifier
更新于2025-09-16 10:30:52
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Radiation Effects in Materials || Effects of Electron Irradiation Upon Absorptive and Fluorescent Properties of Some Doped Optical Fibers
摘要： A review of the recent studies of the effect of irradiating silica-based fibers doped with rare earths and metals by a beam of high-energy (β) electrons is presented. Of the review’s main scope are the attenuation spectra’ transformations occurring in optical fiber of such types under electron irradiation, allowing, from one side, to recover some general essence of the phenomena involved and, from the other side, to draw the features that would make such fibers useful for applications, for example, in dosimetry and space technologies. Among the fibers of the current review’s choice, exemplifying the effect of electron irradiation most brightly, are ytterbium (Yb) and cerium (Ce) (the rare earths’ representatives) and bismuth (Bi) (the post-transitional metals representative) doped fibers, where a diversity of the electron-irradiation-related effects is encouraged.
关键词： optical bleaching,photodarkening,cerium- and bismuth-doped silica fibers,electron irradiation,ytterbium-
更新于2025-09-16 10:30:52
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Laser-cooled ytterbium-ion microwave frequency standard
摘要： We report on the development of a trapped-ion, microwave frequency standard based on the 12.6 GHz hyperfine transition in laser-cooled ytterbium-171 ions. The entire system fits into a 6U 19-in. rack unit (51 × 49 × 28 cm) and comprises laser, electronics, and physics package subsystems. As a first step towards a full evaluation of the system capability, we have measured the frequency instability of our system which is 3.6 × 10?12∕√?? for averaging times between 30 and 1500 s.
关键词： hyperfine transition,frequency instability,laser-cooled ytterbium-ion,microwave frequency standard
更新于2025-09-16 10:30:52
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Ytterbium calcium fluoride waveguide laser
摘要： Calcium fluoride is a well-known material for optical components. It is also suited for doping with rare-earth ions, e.g., ytterbium ones. Yb:CaF2 is an efficient gain medium for high-power and ultrashort-pulse bulk lasers around 1 μm. We report on the first Yb:CaF2 planar waveguide laser. High-optical-quality single-crystalline waveguiding Yb:CaF2 thin films are grown on bulk CaF2 substrates by Liquid Phase Epitaxy. The spectroscopic study indicates the predominant coordination of isolated Yb3+ ions in trigonal oxygen-assisted sites, C3v(T2). The optical gain in Yb:CaF2 waveguide is demonstrated. A 1.4 at.% Yb:CaF2 planar waveguide laser generated 114 mW at 1037 nm with a slope efficiency of 12.9%. Yb:CaF2 films are promising for power-scalable waveguide mode-locked lasers and amplifiers.
关键词： Waveguide laser,Liquid Phase Epitaxy,Optical gain,Ytterbium,Calcium fluoride
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Raman Based Power Combining and Wavelength Conversion of Multiple Fiber Lasers — Number Scaling and Limits on Wavelength Separation
摘要： Cascaded Raman fiber lasers (CRFLs) based on random distributed feedback (RDFB) enable high-power fiber lasers at arbitrary wavelength bands [1,2]. To enable further power scaling in these systems, we recently proposed the use of multiple low-power pump sources instead of a single high-power pump laser [3]. Simultaneous power combining and wavelength conversion of two independent Ytterbium (Yb) lasers operating at different wavelengths into a single lasing wavelength at 1.5μm was demonstrated [3]. However, the questions on whether this technique works for more than 2 pump inputs and with arbitrary wavelength separation were unanswered. Here, we demonstrate that the technique works for more than 2 pump inputs and also with wavelength separation between the pump varying from 5nm to 29nm.
关键词： wavelength separation,power combining,Raman fiber lasers,Ytterbium lasers,wavelength conversion
更新于2025-09-12 10:27:22
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Research of technological possibility of increasing erosion resistance rotor blade using laser cladding
摘要： The publication describes the results of the research of the influence of the parameters of the mode of a laser deposition on the metallurgy of deposited layers, mechanical characteristics and deformations of the samples. Plates, which had made of PC E36 steel and 15Cr11MoW steel, were used as samples. According to the results of experimental researches the peripheral areas of the input edges of the blades were made. Also, an experimental research was conducted on how the parameters of the mode and trajectory of the deposition influence on mechanical and operational characteristics, as well as the deformations forming in the product during the laser surfacing of the Stellite 6 alloy influence on the heat-resistant high-alloy steel 15Cr11MoW.
关键词： Rotor blade,15Cr11MoW,Stellite 6,ytterbium fiber laser,cladding blade,РС Е36,Inconel 625,laser cladding
更新于2025-09-12 10:27:22
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Laser drilling of micro-holes in single crystal silicon, indium phosphide and indium antimonide using a continuous wave (CW) 1070 nm fibre laser with millisecond pulse widths
摘要： The laser micro-drilling of “thru” holes, also known as via holes, in Si, InP and InSb semiconductor wafers was studied using millisecond pulse lengths from an IPG Laser Model YLR-2000 CW multimode 2 kW Ytterbium Fibre Laser and a JK400 (400 W) fibre laser, both with 1070 nm wavelength. The flexibility of this laser wavelength and simple pulsing scheme were demonstrated for semiconductor substrates of narrow (InSb Eg 0.17 eV) and wide (InP Eg 1.35 eV)) room-temperature bandgap, Eg, with respect to the photon energy of 1.1 eV. Optical microscopy and cross-sectional analysis were used to quantify hole dimensions and the distribution of recast material for all wafers and, for silicon, any microcracking for both (100) and (111) single crystal surface Si wafer orientations. It was found that the thermal diffusivity was not a sufficient parameter for predicting the relative hole sizes for the Si, InP and InSb single crystal semiconductors studied. Detailed observations for Si showed that, between the threshold energies for surface melting and the irradiance for drilling a “thru” hole from the front surface to rear surface, there was a range of irradiances for which micro-cracking occurred near the hole circumference. The directionality and lengths of these microcracks were studied for the (100) and (111) orientations and possible mechanisms for formation were discussed, including the Griffith criterion for microcracks and the failure mechanism of fatigue usually applied to welding of metals. For Si, above the irradiance for formation of a thru-hole, few cracks were observed. Future work will compare similar observations and measurements in other narrow- and wide-bandgap semiconductor wafer substrates. We demonstrated one application of this laser micro-drilling process for the micro-fabrication of a thru hole precisely-located in the centre of a silicon-based atom chip which had been patterned using semiconductor lithographic techniques. The end-user application was a source of magneto-optically trapped (MOT) cold atoms of Rubidium (87Rb) for portable quantum sensing.
关键词： microcrack,InP,Si,Griffith criterion,pulse,atom chip,Ytterbium fibre laser,semiconductor material,Fibre laser,semiconductor wafer,laser drilling,silicon,magneto-optical trap,MOT,via hole,laser micro-drilling,cold atoms,InSb,thru hole
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - High Efficiency, High Energy Few-Cycle Driver at 1-μm
摘要： The recent development of high repetition rate lasers based on ytterbium-doped fiber amplifiers (YDFA), has paved the way to increase the repetition rate (>100 kHz) of coherent extreme ultra violet (XUV) sources generated by high harmonic generation (HHG). High repetition rate HHG driver comes with several advantages, such as increased photon flux [1], reduction of the acquisition time in coincidence experiments to study molecular dynamics such as COLTRIMS, and the possibility to study the electronic structure of matter via photoemission spectroscopy and microscopy, where low doses are needed to avoid space-charge effects [2]. Up to now, the overall majority of HHG studies and applications has been restricted to the low repetition rates of Ti:sapphire lasers. Commonly, Ti:sapphire lasers delivers 20 fs pulses at a central wavelength λ = 800 nm, with pulse energies up to hundreds of mJ. However, the average power of these laser systems cannot easily be scaled beyond 10 W, restricting HHG at low repetition rates (up to 10 kHz). Currently, the most mature and powerful ultrafast source technology is undoubtedly ytterbium-based systems, with average power levels beyond 1 kW [3] and numerous industrial applications. However, the long pulse duration of around >200 fs delivered by YDFA sources limits their relevance to this application field. Therefore, nonlinear compression setups have been used successfully to reduce the pulse duration and obtain XUV photon flux among the highest ever reported for HHG-based sources [1]. However, to reach sub-3 cycles regime (< 10 fs at 1030 nm), which is typically required in combination with gating techniques to obtain isolated attosecond pulses, two stages of compression must usually be implemented [4]. This reduces the energy efficiency of the systems dedicated to attosecond physics to typically less than 30% of the overall YDA energy. Here, we demonstrate a two-cycle-source based on a high-energy femtosecond YDFA followed by a hybrid two-stage nonlinear compression setup. The association of a multipass cell-based stage and large-diameter capillary stage provides a compression factor of 48 with an overall transmission of 61%. This source is, to the best of our knowledge, the most efficient few cycle, high energy and high repetition rate laser demonstrated to date. It is very compact with an overall footprint of 1.8 m × 1.0 m and provides a stable train of few-cycle pulses at a central wavelength of 1030 nm that has been continuously characterized over more than 8h. The delivered 6.8 fs (see Fig. 1) 140 μJ pulses at 150 kHz repetition rate, corresponding to 21 W average power, are ideally suited to drive high-photon flux XUV sources [5] through HHG. The described laser system is robust, compact, and power efficient, making it an ideal driver laser for application-ready high flux XUV and attosecond sources.
关键词： attosecond pulses,high harmonic generation,ytterbium-doped fiber amplifiers,extreme ultra violet,high repetition rate lasers
更新于2025-09-12 10:27:22
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Impact of Host Composition, Co-doping or Tri-doping on Quantum Cutting Emission of Ytterbium in Halide Perovskite Quantum Dots and Solar Cells Applications
摘要： Recently, various lanthanide ions (Ln3+) have been successfully doped into perovskite quantum dots (PQDs) and quantum-cutting emission of 2F5/2-2F7/2 for Yb3+with measurable inner efficiency more than 100 % has been discovered, applied as the luminescent converter of solar cells, which has opened a new branch for the application of PQDs. In this work, to further improve the quantum-cutting efficiency of Yb3+, the co-doping and tri-doping methods were displayed to improve the quantum cutting emission of PQDs. The Yb3+-Ln3+ (Ln=Nd, Dy, Tb, Pr, Ce) pairs doped CsPbClxBryI3-x-y PQDs were fabricated, which all displayed excitonic emissions, narrow-band emission of Ln3+ ions and quantum cutting emission of Yb3+ ions. It was interesting to observe that Yb3+-Pr3+ as well as Yb3+-Ce3+ pairs could effectively sensitize the emission of Yb3+, owing to Pr3+ and Ce3+ ions offered intermediate energy states close to the exciton transition energy of the PQDs. After host composition optimization and tri-doping investigation, overall emissions with 173% photoluminescence quantum yield (PLQY) were obtained in the Yb3+-Pr3+-Ce3+ tri-doped CsPbClBr2 PQDs. Then, the tri-doped PQDs was designed as the down-converter for the CuIn1-xGaxSe2 (CIGS) as well as the silicon solar cells, which relatively leads to enhancement of power conversion efficiency (PCE) as high as ～ 20%. The modified CIGS was further employed to charging the smart mobile phone, which could largely shorten the charging time from 180 to 150 min. This finding is of great significant for expanding the application fields of the impurity doped PQDs.
关键词： CIGS solar cell,ytterbium doping,quantum cutting,tri-doping method,Perovskite quantum dot
更新于2025-09-11 14:15:04
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Ytterbium-doped fiber laser as pulsed source of narrowband amplified spontaneous emission
摘要： We report random noise pulsed regime of an ytterbium-doped fiber laser arranged in common Fabry-Perot configuration. We show that the laser output obeys the photon statistics inherent to narrowband amplified spontaneous emission and that the noise pulsing is properly addressed in terms of probability density and autocorrelation functions. Our novel approach reveals, in particular, that the regime’s coherence time dramatically shortens, from few ns to tens ps, with increasing laser power.
关键词： narrowband amplified spontaneous emission,coherence time,photon statistics,probability density,ytterbium-doped fiber laser,autocorrelation functions,random noise pulsed regime
更新于2025-09-11 14:15:04