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Diamond Brillouin laser in the visible
摘要： Brillouin lasers providing extremely narrow-linewidth are emerging as a powerful tool for microwave photonics, coherent communications, quantum processors, and spectroscopy. So far, laser performance and applications have been investigated for a handful of select materials and using guided-wave structures such as micro-resonators, optical fibers, and chip-based waveguides. Here, we report a Brillouin laser based on free-space laser action in an extreme optical material. Continuous-wave lasing 167 GHz from a 532 nm pump is demonstrated in diamond using a doubly resonant ring cavity, generating a pump-limited output power of 11 W. The Brillouin gain coefficient is measured to be 79 cm GW?1 with a linewidth of 12 MHz. These properties, along with an exceptionally high Brillouin frequency and wide transmission range, make diamond Brillouin lasers a promising high-power source of narrow-linewidth output and mm-wave beat notes.
关键词： narrow-linewidth,quantum processors,microwave photonics,diamond,Brillouin lasers,spectroscopy,coherent communications
更新于2025-09-19 17:13:59
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Ultra-short Pulsed Laser Conditioning of Metallic-bonded Diamond Grinding Tools
摘要： A novel approach for machining of cylindrical ultra-hard materials with a highly defined contour is presented. Diamond grinding tools with complex geometry are manufactured with picosecond orthogonal and quasi-tangential laser ablation. Hitherto, laser manufacturing required a special axis configuration and optical beam deflection devices are utilized. Here, strategies and processes on a scanhead-free configuration using ultra-short pulsed laser are discussed enabling straight-forward implementation in industry. This rapid and flexible approach for the production of master tools for industrial grinding processes reveals benefits compared to conventional techniques. The manufacturing time is comparable to standard processes, however, increased grain protrusion is attained with the presented laser sharpening strategy. An ablation study for maximal material-removal rate reveals the impact of wavelength, strategy, and repetition rate at high average power up to 100 W. A combined laser manufacturing routine enables an ablation rate of 35 mm3 min?1 and a maximal geometric deviation of 3 μm after finishing. The final grinding tools are sharpened by a radial laser process preferentially removing the metal-based binding material. Hence, high-precision diamond grinding wheels with a mean error of smaller 1 μm over millimeter-sized contours can be manufactured. The meta-stable diamond structure persists and is assessed via Raman spectroscopy studies at laser cut grains.
关键词： Raman spectroscopy,laser manufacturing,diamond grinding tool,ultra-short pulses,precision machining,laser conditioning
更新于2025-09-19 17:13:59
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Interaction of Methane Concentration and Deposition Temperature in Atmospheric Laser Based CVD Diamond Deposition on Hard Metal
摘要： For laser-based plasma chemical vapour deposition (CVD) of diamond on hard metal at atmospheric pressure, without a vacuum chamber, the interaction between the deposition temperature and the methane concentration has to be understood to adjust the coating thickness, deposition duration, and medium diamond crystal size. The hypothesis of this study is that a wider range of methane concentrations could be used to deposit microcrystalline diamond coatings due to the increasing etching and deposition rates with rising deposition temperatures. The deposition of the CVD diamond coatings was carried out on K10 hard metal substrates. The process temperature and the methane concentration were varied from 650 to 1100°C and from 0.15% to 5.0%, respectively. The coatings were analysed by scanning electron and 3D laser-scanning confocal microscopy, energy dispersive X-ray and micro-Raman spectroscopy, as well as cryofracture-based microscopy analysis. The results showed that microcrystalline diamond coatings could be deposited in a wider range of methane concentrations when increasing the process temperature. The coating thickness saturates depending on the process temperature even though the methane concentration constantly increases. The coating thickness increases with an increasing deposition temperature until the cobalt diffusion hinders the deposition at the process temperature of 1100°C.
关键词： diamond film,chemical vapour deposition,hard metal,methane ratio,deposition temperature
更新于2025-09-19 17:13:59
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Sub-micron structuring/texturing of diamond-like carbon-coated replication masters with a femtosecond laser
摘要： Diamond-like carbon (DLC) coatings have very attractive mechanical and tribological properties, i.e. high hardness, low friction and high wear resistance. Therefore, DLC is often used as a solid lubricant in moulds for injection moulding. Laser processing of DLC with ultrashort lasers, i.e. femtosecond lasers, can be performed both at micron and sub-micron scales, namely by producing laser-induced periodic surface structures (LIPSS). In this research, the effects of laser structuring/texturing on DLC properties are investigated. First, the laser-processing parameters were optimised to produce uniform LIPSS without damaging a thin DLC film and then the properties of the textured DLC-coated substrates were studied. It was determined that the tribological properties of the processed surfaces remained unchanged, but the hardness of the structured/textured DLC layers was reduced significantly. Although GAXRD and Raman spectroscopy did not show any significant crystallisation of the DLC coating after the laser irradiation, the analysis indicated that a thin graphitised layer had been formed on the surface as a result of the femtosecond laser processing.
关键词： Laser microprocessing,Femtosecond laser,LIPSS,Diamond-like carbon (DLC)
更新于2025-09-19 17:13:59
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[IEEE 2019 FISE-IEEE/CIGRE Conference - Living the energy Transition (FISE/CIGRE) - Medellin, Colombia (2019.12.4-2019.12.6)] 2019 FISE-IEEE/CIGRE Conference - Living the energy Transition (FISE/CIGRE) - Considerations for the Assessment Resilience in Low Voltage Electrical Network with Photovoltaic Systems a?? Part I
摘要： Resilience promises to be a concept to integrally evaluate the operation of an electrical grid, to guarantee in the robustness, reliability, adaptability, and restoration electrical system. Resilience is mainly studied to analyse the negative effects caused by high impact events and low probability of occurrence (e.g. natural disasters) in power systems and medium voltage distribution networks. This paper aims to present considerations about the assessment of resilience to evaluate a low-voltage power grid with photovoltaic systems. The resilience level may be a unique quantitative value that defines in real-time the operational state of the electrical grid. This paper proposes the resilience evaluation in 1 to 10-minute observation window using four concepts, given weights to each concept and proposing two-visualization form of resilience. Therefore, this research proposes the resilience study in low voltage networks that integrate distributed resources, seeking to highlight the importance of evolution-temporary evaluation.
关键词： resilience diamond,Low voltage,photovoltaic systems.,resilience curve
更新于2025-09-19 17:13:59
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Effects of LED Light Color and Intensity on Feather Pecking and Fear Responses of Layer Breeders in Natural Mating Colony Cages
摘要： The friction properties play an important role in diamond polishing, which significantly affect the interfacial contact and material removal. In this paper, the friction force and coefficient of friction (COF) during diamond polishing process were monitored under different loads and rotating speeds. The results show that the friction force and COF both increase with the load, and decrease with the rotating speed. The bearing capacity of liquid film is enhanced at large rotating speed, which leads to the decrease of friction force. According to the binomial law of friction, the increase of actual contact area caused by high load contributes to the increase of COF. Besides, it is found that the addition of H2O2 reduces the friction coefficient through surface adsorption. In order to further reveal the mechanism of friction variation at the atomic level, the friction behavior at a local area of interface between the diamond substrate and the abrasive particle in diamond polishing process was investigated by molecular dynamics (MD) method. The simulation results indicate that the interfacial bridge bonds formed between the substrate and particle under the action of load lead to the increase of friction force.
关键词： molecular dynamics,coefficient of friction,diamond,friction,polishing
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Ultrathin Self-feeding Metasurface with Broadband Polarization Conversion and Electromagnetic Emission
摘要： A model for controlling the two-dimensional distribution of negatively charged nitrogen-vacancy (NV?) fluorescent centers near the surface of a diamond crystal is presented, using only a microwave plasma-assisted chemical vapor deposition (CVD) method. In this approach, a CVD diamond layer is homoepitaxialy grown via microwave plasma-assisted CVD using an isotopically enriched methane (12CH4 ), hydrogen (H2 ), and nitrogen (N2 ) gas mixture on patterned diamond (0 0 1). When the surface is imaged by means of confocal microscope photoluminescence mapping, fine grooves are observed to have been generated artificially on the diamond surface. NV? centers are found to be distributed selectively into these grooves. These results demonstrate an effective means for the formation of NV? centers of selectable size and density via microwave plasma-assisted CVD, with potential application in the production of diamond quantum sensors.
关键词： doping,nitrogen-vacancy centers,homoepitaxial,groove structure,Diamond,microwave plasma-assisted chemical vapor deposition
更新于2025-09-19 17:13:59
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Phononic-waveguide-assisted steady-state entanglement of silicon-vacancy centers
摘要： Multiparticle entanglement is of great significance for quantum metrology and quantum information processing. We present here an efficient scheme for generating stable multiparticle entanglement in a solid-state setup, where an array of silicon-vacancy centers are embedded in a quasi-one-dimensional acoustic diamond waveguide. In this scheme, the continuum of phonon modes induces a controllable dissipative coupling among the SiV centers. We show that, by an appropriate choice of the distance between the SiV centers, the dipole-dipole interactions can be switched off due to destructive interference, thus realizing a Dicke superradiance model. This gives rise to an entangled steady state of SiV centers with high fidelities. The protocol provides a feasible setup for the generation of multiparticle entanglement in a solid-state system.
关键词： Multiparticle entanglement,quantum information processing,acoustic diamond waveguide,quantum metrology,silicon-vacancy centers,Dicke superradiance model
更新于2025-09-19 17:13:59
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Table-top nuclear magnetic resonance system for high-pressure studies with <i>in situ</i> laser heating
摘要： High pressure Nuclear Magnetic Resonance (NMR) is known to reveal the behavior of matter under extreme conditions. However, until now, significant maintenance demands, space requirements, and high costs of superconducting magnets render its application unfeasible for regular modern high pressure laboratories. Here, we present a table-top NMR system based on permanent Halbach magnet arrays with a diameter of 25 cm and height of 4 cm. At the highest field of 1013 mT, 1H-NMR spectra of ice VII have been recorded at 25 GPa and ambient temperature. The table-top NMR system can be used together with double sided laser heating setups. Feasibility of high-pressure high-temperature NMR was demonstrated by collecting 1H-NMR spectra of H2O at 25 GPa and 1063(50) K. The change in the signal intensity in a laser-heated NMR diamond anvil cell has been found to yield a convenient way for temperature measurements.
关键词： diamond anvil cell,laser heating,Halbach magnet,Nuclear Magnetic Resonance,high-pressure
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) - Fabrication of High Quality Quantum Emitters in Diamond Nanostructures
摘要： As the field of solid-state quantum engineering matures, it is increasingly necessary to produce quantum emitters with narrow optical transitions and long spin coherence times aligned to nanophotonic structures. The nitrogen-vacancy (NV) defect center in diamond is a well-suited candidate owing to a spin ground state with a long coherence time, nearby nuclear spins for quantum memories, and spin-selective optical transitions allowing for efficient optical spin initialization and readout. We demonstrate an emitter-device alignment technique enabling fabrication of photonic devices registered to NVs. The alignment method relies on autonomously imaging emitters and registering them relative to an on-chip coordinate system. This technique can be performed on a large variety of emitters. The repeatability of this method suggests a spatial accuracy of 50 nm. The ability to navigate a sample autonomously facilitates data collection on a large number of NVs, thus permitting statistical analyses. We utilized this approach to correlate the NV’s host nitrogen isotope with the optical linewidth of the emitter to understand the effects of implantation. As shown in Fig. 1a, the data indicate that the coherent, narrow-linewidth NVs are formed from naturally abundant nitrogen (14N), whereas the implanted nitrogens (15N), on average, yield broader linewidth NVs. The implanted 15NVs also exhibit larger axial and transverse strains suggesting that damage was produced near the emitter. We attribute the broad linewidths of implanted 15NVs to a more volatile local environment generated by local damage resulting from the ion implantation process.
关键词： diamond nanostructures,nanophotonic structures,nitrogen-vacancy center,spin coherence,quantum emitters
更新于2025-09-16 10:30:52