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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - In Situ Transmission Electron Microscopy: A Powerful Tool for the Characterization of Carrier-Selective Contacts
摘要： This paper investigates the manufacturability-aware process of p-n junction formation for photovoltaic cells involving with Si nanoparticle layer. The furnace-based dopant diffusion process of forming a p-n junction consumes a substantial amount of energy. In addition, repetitive production steps prevent the possibility of Si ink-based cells integrating onto flexible substrates. This research examined the local heating dopant diffusion process by using a fiber laser at a wavelength of 1064 nm. The infrared beam is delivered onto the wafer stack with a nanoparticle carbon layer and n-type Si ink layer on p-type Si substrates. The nanoparticle carbon film absorbs infrared beam energy and converts photon energy as a thermal source to diffuse the n-type dopant in Si ink into the p-type Si wafer. The Si ink in this paper contains a mixture of Si nanoparticles and an n-type spin-on dopant solution. The TEM results show that Si nanoparticles are uniformly dispersed on the Si wafer surface. This research investigated sheet resistance as a function of laser parameters, including laser power, scanning speed, and pulse frequency for the samples coated with Si ink. Secondary ion mass spectroscopy measurements indicate the presence of an n-type dopant in p-type substrates, with an approximate diffusion depth of 100 nm. The results indicate that the proposed infrared laser treatment technique is promising for the formation of p-n junctions with Si ink-based photovoltaic cells.
关键词： Flexible photovoltaic cell,fiber laser,pn junction,spin-on dopant (SOD),silicon ink,carbon nanoparticle,silicon nanoparticle
更新于2025-09-19 17:13:59
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High Conversion Efficiency, Mid-Infrared Pulses Generated via Burst-Mode Fiber Laser Pumped Optical Parametric Oscillator
摘要： We present a mid-infrared optical parametric oscillator (OPO) with a high pump-to-idler conversion efficiency from 1.06 μm to 3.8 μm, which was quasi-synchronously pumped by a burst-mode fiber laser. The pump pulse was specially designed with a rectangular profile in temporal, which was composed of hundreds of ultrashort sub-pulses. By applying the quasi-synchronous pumping scheme, the buildup time of the parametric signal pulse could be minimized. No back-conversion effect was observed when the pump peak power was increased. A maximum pump-to-idler conversion efficiency of 19.6% was achieved when the number of intra-burst sub-pulses was set to be 240. By increasing the number of intra-burst sub-pulses to be about 480, the maximum average output power of 7.9 W at 3.8 μm was realized under pump power of 45.3 W. The corresponding pump-to-idler conversion efficiency was computed to be about 17.5%. The experimental results show an improvement of 40% in pump-to-idler conversion efficiency for this quasi-synchronously pumped OPO when compared with the conventional long laser pulse pumped OPO.
关键词： burst-mode fiber laser,quasi-synchronously pumped,mid-infrared,optical parametric oscillator
更新于2025-09-19 17:13:59
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Fiber laser spot welding of molybdenum alloy in a hyperbaric environment
摘要： The e?ect of the growth of ambient pressures on the penetration of laser welded molybdenum (Mo) alloy was explored. It was found that when ambient pressure rose from 0.1 MPa to 1.8 MPa, the penetration of base metal (BM) was signi?cantly reduced, which was only 17% of that obtained under ambient pressure of 0.1 MPa. Moreover, the mechanism underlying the signi?cant reduction of the penetration of BM was analyzed. At ?rst, by using a high-resolution scanning electron microscope (SEM), the size and the number of nano-sized metallic particles generated during laser welding under di?erent ambient pressures were surveyed. Furthermore, the scattering and absorption of the nano-sized metallic particles for laser energy under di?erent ambient pressures were investigated; afterwards, by applying a high-speed camera and a spectrometer, the transient behaviors and spectral signals of plasmas during ?ber laser spot welding under di?erent ambient pressures were monitored. On this basis, the inverse bremsstrahlung absorption of plasmas for laser energy under di?erent ambient pressures was explored; ?nally, ?ber laser spot welding test was carried out on glass/metal composite samples under di?erent ambient pressures to survey the in?uence of the change of ambient pressure on dynamic behaviors of the molten pool during the welding.
关键词： penetration,nano-sized metallic particles,molybdenum alloy,spot welding,fiber laser,hyperbaric environment,plasmas,molten pool
更新于2025-09-19 17:13:59
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Niobium disulfide as a new saturable absorber for an ultrafast fiber laser
摘要： Group VB transition metal dichalcogenides (TMDCs) are emerging two-dimensional materials and have attracted significant interests in the fields of physics, chemistry, and material sciences. However, there are very few reports about the optical characteristics and ultrafast photonic applications based on group VB TMDCs so far. In this work, we have calculated the niobium disulfide (NbS2) band structure by the density functional theory (DFT), which has revealed that NbS2 is a metallic TMDC. In addition, we have prepared an NbS2-microfiber device and the nonlinear optical characteristics have been investigated. The modulation depth, saturation intensity and non-saturable loss have been measured to be 13.7%, 59.93 MW cm?2 and 17.74%, respectively. Based on the nonlinear optical modulation effect, the Er-doped fiber (EDF) laser works in the soliton mode-locking state with the pump power of 94–413 mW. The pulse duration of 709 fs and the maximum average output power of 23.34 mW have been obtained at the pump power of 413 mW. The slope efficiency is as high as 6.79%. Compared to the recently reported studies based on TMDCs comprehensively, our experimental results are better. These experimental results demonstrate that NbS2 with excellent nonlinear optical properties can be used as a promising candidate to advance the development of ultrafast photonics.
关键词： Niobium disulfide,ultrafast fiber laser,saturable absorber,mode-locking,nonlinear optical properties
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 14th Malaysia International Conference on Communication (MICC) - Selangor, Malaysia (2019.12.2-2019.12.4)] 2019 IEEE 14th Malaysia International Conference on Communication (MICC) - Investigation of Q-switched and Mode-Locked Erbium-Doped Fiber Laser Using Graphene oxide-Saturable Absorber
摘要： This paper experimentally investigates a simple configuration of an erbium-doped fiber laser (EDFL) cavity to generate mode-locked and Q-switched pulses utilize graphene oxide as saturable absorber (GO-SA). The GO-SA chip is a chip placed as a sandwich between two fiber ferrules and incorporates a ring laser cavity to generate a pulse train. Results indicate that the cavity of passive Q-switching EDFL is capable of providing pulses at 1532nm with a pulse width within a range of 5.32μs to 2.6μs, a repetition rate of 59.5kHz to 71.74kHz, a pulse energy of 364.64nJ to 668.95nJ, and an output power ranging from 0.062mW to 0.136mW, when the configuration is pumped by a 980nm laser diode, the power of which gradually increases from 21.7mW to 47.9mW. The output of the GO-SA needs to be connected to 200m of a single-mode fiber (SMF) to generate mode-locked pulses at 1559nm when the pump power is 157.6mW. As a result, an output power of 1.29mW is delivered with a repetition rate of 1.002MHz.
关键词： Erbium-Doped Fiber Laser,Q-switched,Saturable Absorber,Mode-Locked,Graphene oxide
更新于2025-09-19 17:13:59
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Formation of the Feedback Loop for Phase Control of a Fiber Laser Array
摘要： Methods for phasing radiation channels for the coherent combination of linearly polarized fields of narrowband fiber lasers are considered. High efficiency of operation of the internal feedback loop based on interference of peripheral sections of radiation (Gaussian beam tails) of the phased channels is shown. This method is easily implementable. It allows scaling the power of optical phased arrays and does not require heavy optical elements. Equations for calculation of the optical scheme for implementation of the feedback loop are presented along with the experimental results on coherent combination of three beams.
关键词： optical phased arrays,feedback loop,coherent combining,fiber laser
更新于2025-09-19 17:13:59
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Observation of visible light flashes in high power near infrared narrow linewidth polarization maintained fiber laser caused by Stimulated Brillouin Scattering triggered cascaded Raman Scattering
摘要： We report a surprising observation of visible light flashes in the fusion splice point between the seed stage to the power amplifier in a 500 W narrow-linewidth, polarisation-maintaining Ytterbium-doped fiber laser. The flashes were observed to have a strong correlation with the backward pulses generated due to the onset of Stimulated Brillouin Scattering (SBS) in the laser. We believe these visible flashes appear as a result of second harmonic generation of higher order Raman Stokes components of the 1064nm laser signal. The Raman components are generated by the back-propagating, high peak power SBS pulses at threshold. The Raman Stokes in the core of the fiber generates their respective second harmonic counterparts in the cladding through a Cherenkov-type phase matching process.
关键词： Brillouin Scattering,Fiber laser,Cherenkov phase matching,Raman Scattering
更新于2025-09-19 17:13:59
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Alternation of the Mode Synchronization and Desynchronization in Ultrafast Fiber Laser
摘要： Ultrafast fiber lasers offer a unique opportunity to implement optically a Poincaré mapping in the phase space of a variety of complex dissipative dynamical systems operating far from the equilibrium. Understanding of such complex optical dynamical systems revealing, for instance, ultrafast dynamics of the dissipative solitons (DSs) and more complex regimes is important for advancing specification and performance of the mode-locked lasers used in a vast number of applications ranging from spectroscopy and medicine to metrology and telecom. Here, using the mode-locked fiber laser as a test-bed, the Shilnikov-type ultrafast dynamics taking the form of randomly switching between noise-like pulsing and quasi-continuous-wave regimes is experimentally demonstrated. The transient coherence recovery is revealed, during which the noise-like pulse (NLP) is transformed into a coherent DS state and then returned to an incoherent NLP state. The demonstrated alternation of mode synchronization and desynchronization is both of practical importance for developing new types of partially mode-locked lasers and of the fundamental interest for the nonlinear science in the context of revealing routes to the turbulence in distributed nonlinear systems.
关键词： optical spectroscopy,nonlinear optics,fiber laser
更新于2025-09-19 17:13:59
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Polarization-dependent pulse dynamics of mode-locked fiber laser with near-zero net dispersion
摘要： We demonstrate novel polarization-dependent pulse dynamics in a fiber laser cavity mode-locked by single-wall carbon nanotubes. By managing the net dispersion and polarization state, we obtain two noise-like pulsing procedures with distinctive polarization characteristics. Ultrafast polarization measurements reveal double pulses are produced by the combined effects of double-scroll chaotic polarization attractors and the polarization mode dispersion of single-mode fiber. The corresponding single-shot spectra provide evidence of coherent energy coupling between pulses during the switching process, due to the polarization hole burning of the active medium. The relative results provide new information for the polarization control of ultrafast lasers.
关键词： polarization-dependent pulse dynamics,single-wall carbon nanotubes,polarization hole burning,near-zero net dispersion,mode-locked fiber laser
更新于2025-09-19 17:13:59
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Generation of 100??nJ pulse, 1??W average power at from an intermode beating mode-locked all-fiber laser
摘要： We report on the investigation of intermode beating mode-locked (IBML) pulse generation in a simple all-fiber Tm3+-doped double clad fiber laser (TDFL). This IBML TDFL is implemented by matching longitudinal-mode frequency between 793 nm laser and TDFL without extra mode locker. The central wavelength of ～1983 nm, the fundamental pulse frequency of ～9.6 MHz and the signal-to-noise ratio (SNR) of >50 dB are achieved in this IBML TDFL. With laser cavity optimization, the IBML TDFL can finally generate an average output power of 1.03 W with corresponding pulse energy of ～107 nJ. These results can provide an easily accessible way to develop compact large-energy, high-power TDFLs.
关键词： pulse energy,Tm3+-doped double clad fiber laser,average output power,intermode beating mode-locking
更新于2025-09-19 17:13:59