- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Optimization of a supercontinuum source based on tapered ordinary fibers
摘要： In this paper the generation of visible spectrum via optimized supercontinuum generation (SCG) in tapered ordinary fibers by ultrashort laser pulses is presented. The tunability of the visible part of the spectra is achieved by changing the pump pulse duration during operation. The optimization of the SCG is carried out by the investigation of the taper geometry with the emphasis on the downtapering section length. Its increase is found to be correlated to higher intensity in the visible part of the spectra. This is further supported by the results on spectra evolution before it enters the taper waist where an important transfer of the pump power to the shorter wavelengths is found.
关键词： fiber lasers,ytterbium-doped fiber amplifiers,supercontinuum generation
更新于2025-09-23 15:23:52
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Single-mode large-mode-area Er–Yb fibers with core based on phosphorosilicate glass highly doped with fluorine
摘要： Single-mode Er–Yb fibers with the core based on a phosphorosilicate glass matrix (up to 6.5 mol.% P2O5) highly doped with fluorine (up to 0.9 wt.%) were fabricated using an all-gas-phase modified chemical vapor deposition method. The core numerical aperture was in the range of 0.07–0.08 relative to the pure silica, which allowed us to increase the single-mode core diameter up to 20 μm. The slope efficiency in lasers based on the fabricated fibers reached 34% relative to the launched pump power.
关键词： fiber lasers,optical fibers,erbium–ytterbium fibers,erbium-doped fiber amplifiers
更新于2025-09-23 15:22:29
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Environmentally Stable 1.56-??m Femtosecond Laser System With Discontinuous Selectable Repetition Rate
摘要： We demonstrate here an environmentally stable and compact Er-doped fiber laser system capable of delivering sub-100-fs pulse duration with discontinuous selectable repetition rate from 10 to 70 MHz. This laser source employs a SESAM harmonic mode-locked soliton laser to facilitate tunable repetition rate. A single-mode-fiber (SMF) amplifier and a double-cladding-fiber (DCF) amplifier (both with double-pass configuration) bridged by a three-stage YVO4-based divider are used to manage the dispersion map and boost the seed pulses. With the help of ×8 replicas, the seed pulses are simultaneously amplified and compressed with 90% recombining efficiency, generating 4.60-nJ pulse energy at 10 MHz and 6.13-nJ pulse energy at 70 MHz. The main advantage of the proposed laser system is that when pulse repetition rate is switched on-demand, the pulse duration can be kept almost unchanged only by simply adjusting the pump powers of the fiber amplifiers, instead of changing any optical device (the spacing between gratings or the length of fibers).
关键词： fiber amplifiers,Mode-locked Laser,ultrafast laser,tunable repetition rate
更新于2025-09-23 15:21:01
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Effect of P-to-Rare Earth Atomic Ratio on Energy Transfer in Er-Yb-Doped Optical Fiber
摘要： Erbium (Er)- and Ytterbium (Yb)-doped optical fibers (EYDFs) have been used in various industrial fields as the only technology suitable for >1 W high-power amplifiers in the 1550-nm band. The output power is mainly limited by unwanted 1-μm band amplified spontaneous emissions from excited Yb3+; however, the factors affecting the output performance remain unclear. Here, we quantitatively and systematically reveal that the Phosphorus (P)-to-rare earth atomic ratio in the EYDFs has an optimal value for achieving the best output performance of EYDFs. We experimentally evaluated the quantitative relationship among co-dopants by fabricating preforms, drawing them as fibers, and measuring the amplification characteristics. At an appropriate Er concentration (0.3–0.5 wt %), a pump-to-signal conversion efficiency of 45.4% was obtained when the P/(Yb + Er) atomic ratio was around 25. This study paves the way for energy saving in high-power applications, such as high-speed optical wireless communication and long-distance optical ranging.
关键词： Phosphorus,Atomic ratio,Space communications,Energy-transfer efficiency,Amplified spontaneous emission,Erbium-Ytterbium-doped optical fiber amplifiers
更新于2025-09-23 15:21:01
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Optical Fiber Communications (Principles and Applications) || Optical Amplifiers
摘要： An optical amplifier is a widely used device in optical fiber communications for the purpose of amplification of the optical signal generated by an optical transmitter. The optical signal is directly amplified to yield optical signal without any conversion to electrical signal first and then restoring it to amplified optical signal. This implies that optical amplifiers operate on photons in all-optical domain. In essence, optical amplifiers do require source and photodetector as optoelectronic devices and additional electronic circuits for other operations such as shaping of optical pulses including retiming. But why do we need optical amplifiers? We know that typical fiber loss around 1500-nm wavelength is approximately 0.2 dB/km. Let us examine what happens after the optical signals travel about 100 km down the fiber. The signals are attenuated by 20 dB. So they need to be amplified, otherwise the signal-to-noise ratio of detected signals is too low and bit-error-rate becomes too high (typically desired value of BER is <10-9). One way to resolve this issue is to detect the weak signals, followed by modulating a new laser (optical-to-electrical-to-optical conversions) which requires high-speed (>10 GHz) electronic circuitry. Therefore, the best way to amplify the signal is only optically and the preferred method is fiber amplifier which is the most efficient, the most stable and the one with the lowest loss.
关键词： Erbium-doped fiber amplifiers,Raman fiber amplifiers,optical amplifiers,semiconductor optical amplifiers,optical fiber communications
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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Unified Formalism for Erbium-Doped Fiber Amplifiers and Lasers
摘要： A comprehensive and integrated exact analytical formalism is presented for erbium-doped fiber amplifiers and lasers (EDFALs) in one single configuration based on solutions of a system of rate and propagation equations represented by a homogenously broadened four band transition scheme while incorporating amplified spontaneous emission and excited state absorption effects. The formalism, under steady-state conditions, concurrently provides considerable insight into physical characteristics underlying phenomena pertinent to EDFALs and allows precise evaluation of behavior exhibited by EDFALs through a judicious selection of pump intensity and fiber length in standard eye-safe low-erbium concentration uniformly doped mono-mode silica glass fibers in co- and counter- propagating directions appropriate to signal, pump and ASE regimes.
关键词： analytical modeling,erbium-doped fiber amplifiers,optical fiber communication,erbium-doped fiber lasers
更新于2025-09-11 14:15:04
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Few-Mode Erbium-Doped Fiber Amplifier Design Challenges for WDM Optical Networks
摘要： The use of optical spatial division multiplexing (SDM) technologies increases the capacity of the optical channel, allowing higher transmission rates than those observed in wavelength division multiplexing (WDM) optical systems based on single-mode fibers. In particular, spatial multiplexing based on multimode fibers allows the transmission of information in orthogonal modes. In these systems, the erbium-doped fiber amplifier (EDFA) remains essential to compensate for optical link losses. This paper presents the challenges to the development of EDFAs for WDM optical systems based on few-mode fibers, considering the addition of gain flattening filters and correction of gain calculation.
关键词： erbium-doped fiber amplifiers,space division multiplexing,gain equalization,Few-mode fiber amplifier
更新于2025-09-11 14:15:04
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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) - Coherent Beam Combining of Fiber Amplifiers Seeded by Commercial Low Cost Diode
摘要： Coherent beam combining (CBC) is one of the methods for power scaling of high power lasers. In the scientific literatures a low power narrow linewidth source is used for CBC, however in this report, a low cost diode laser source (spectral bandwidth <10 MHz) is used to fabricate near diffraction-limited 300 W fiber laser with CBC method. The diode laser is amplified by a preamp fiber amplifier and then divided in to three channels. Each channel is amplified to achieve 120W output with homemade power amplifiers. A 1×3 diffractive optical element is used to combine the output of the amplifiers with ~83% efficiency. Active phase locking is achieved with the stochastic parallel gradient descent (SPGD) method. A major obstacle towards high power narrow-linewidth fiber lasers is stimulated Brillouin scattering (SBS). It has been proven that phase modulation is an effective way to suppress SBS in these kind of lasers. Applying phase modulation to a single frequency laser, splits its spectrum to many spectral lines with the same frequency spacing of the modulation frequency. In this work, we use a sinusoidal signal phase modulation (30 MHz frequency and 10 V amplitude) to suppress SBS effect. The result of this modulation on the spectrum of the laser is illustrated. The maximum achievable output power for each channel without modulation is ~40 W. However, by applying modulation SBS threshold power enhances with a factor of 3. The output power of combined beam versus pump diode current (solid line) is shown. Also the backward output power (dashed line) is illustrated. As it can be seen in the figure the maximum backward power is 110 μW which proves the SBS effect is cancelled.
关键词： stimulated Brillouin scattering,diode laser,phase modulation,Coherent beam combining,fiber amplifiers
更新于2025-09-11 14:15:04
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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) - A 290 W Radially Polarized Output Power from a Single-Stage Single-Crystal Yb:YAG Amplifier
摘要： Radially polarized beams exhibit interesting properties for material processing, as well as for different scientific applications such as optical trapping, plasmon excitation or data storage. With a thin-disk multipass amplifier radially polarized ultra-short pulses with an average output power of 635 W were demonstrated in [1]. For 100 W class operation, single-crystal fiber (SCF) amplifiers are an alternative approach to the thin-disk architecture. This approach reduces the costs and the complexity of the overall laser system significantly. The highest average output power demonstrated with an SCF amplifier was 160 W for a linearly polarized Gaussian seed beam [2] and 85 W for a ring-shaped radially polarized seed beam [3]. In this contribution, we present the amplification of a ring-shaped radially polarized seed beam in a single-stage SCF amplifier to an average output power of 290 W in continuous-wave (CW) operation and 270 W in femtosecond pulsed operation. This is, to the best of our knowledge, the highest average output power of a radially polarized beam demonstrated so far with an SCF amplifier.
关键词： femtosecond pulses,Radially polarized beams,high power lasers,single-crystal fiber amplifiers
更新于2025-09-11 14:15:04