In this paper,an absorption spectroscopy measurement method was applied on two atmospheric pressure plasma sources to determine their production of nitric oxide.The concentrations are essential for evaluating the plas...In this paper,an absorption spectroscopy measurement method was applied on two atmospheric pressure plasma sources to determine their production of nitric oxide.The concentrations are essential for evaluating the plasma sources based on the principle of the Dielectric Barrier Discharge（DBD）for applications in plasma medicine.The described method is based on a setup with an electrodeless discharge lamp filled with a mixture of oxygen and nitrogen.One of the emitted wavelengths is an important resonance wavelength of nitric oxide（λ = 226.2 nm）.By comparing the absorption behaviour at the minimum and maximum of the spectral absorption cross section of nitric oxide around that wavelength,and measuring the change in intensity by the absorbing plasma,the concentration of nitric oxide inside the plasma can be calculated.The produced nitric oxide concentrations depend on the pulse duration and are in the range of 180 ppm to 1400 ppm,so that a distance of about 10 cm to the respiratory tract is enough to conform to the VDI Guideline 2310.展开更多
Multi-beam laser processing is a very popular method to improve processing efficiency. For this purpose, a compact and stable multi-beam pulsed 355 nm ultraviolet(UV) laser based on a micro-lens array(MLA) is presente...Multi-beam laser processing is a very popular method to improve processing efficiency. For this purpose, a compact and stable multi-beam pulsed 355 nm ultraviolet(UV) laser based on a micro-lens array(MLA) is presented in this Letter. It is worth noting that the MLA is employed to act as the spatial splitter as well as the coupling lens. With assistance of the MLA,the 1064 nm laser and 532 nm laser are divided into four sub-beams and focused at different areas of the third-harmonic generation(THG) crystal. As a result, the multi-beam pulsed 355 nm UV laser is successfully generated inside the THG crystal. The measured pulse widths of four sub-beams are shorter than 9 ns. Especially, the generated four sub-beams have good long-term power stability benefitting from the employed MLA. We believe that the generated stable multi-beam355 nm UV laser can meet the requirement of high-efficiency laser processing, and the presented method can also pave the way to generate stable and long-lived multi-beam UV lasers.展开更多
We report the first demonstration of high-efficiency ultraviolet(UV)pulse generation in a resonance-free anti-resonant hollow-core fiber(AR-HCF).Using the wet-etching technique,we successfully reduced the cladding-tub...We report the first demonstration of high-efficiency ultraviolet(UV)pulse generation in a resonance-free anti-resonant hollow-core fiber(AR-HCF).Using the wet-etching technique,we successfully reduced the cladding-tube wall thickness of the AR-HCF to 115 nm,thereby eliminating all cladding-induced structural resonances between the near-infrared pump and the deep UV wavelengths.This structural modification fundamentally suppresses competing conversion to other phase-matching points induced by structural resonances and mitigates the pump spectral broadening limitation,achieving a UV conversion efficiency as high as 12%—twice that of previous demonstrations in gas-filled AR-HCFs.This UV conversion efficiency is comparable to that of meter-scale gas-filled capillaries that require pump pulse energy of hundreds of microjoules while also maintaining the AR-HCF's inherent advantages of centimeter-scale compactness and low pump energy at the few microjoule level.展开更多
文摘In this paper,an absorption spectroscopy measurement method was applied on two atmospheric pressure plasma sources to determine their production of nitric oxide.The concentrations are essential for evaluating the plasma sources based on the principle of the Dielectric Barrier Discharge（DBD）for applications in plasma medicine.The described method is based on a setup with an electrodeless discharge lamp filled with a mixture of oxygen and nitrogen.One of the emitted wavelengths is an important resonance wavelength of nitric oxide（λ = 226.2 nm）.By comparing the absorption behaviour at the minimum and maximum of the spectral absorption cross section of nitric oxide around that wavelength,and measuring the change in intensity by the absorbing plasma,the concentration of nitric oxide inside the plasma can be calculated.The produced nitric oxide concentrations depend on the pulse duration and are in the range of 180 ppm to 1400 ppm,so that a distance of about 10 cm to the respiratory tract is enough to conform to the VDI Guideline 2310.
基金supported by the National Natural Science Foundation of China (Nos. 61975100 and 62027821)Program for the Innovative Talents of High Education Institutions of ShanxiFund for Shanxi “1331 Project” Key Subjects Construction
文摘Multi-beam laser processing is a very popular method to improve processing efficiency. For this purpose, a compact and stable multi-beam pulsed 355 nm ultraviolet(UV) laser based on a micro-lens array(MLA) is presented in this Letter. It is worth noting that the MLA is employed to act as the spatial splitter as well as the coupling lens. With assistance of the MLA,the 1064 nm laser and 532 nm laser are divided into four sub-beams and focused at different areas of the third-harmonic generation(THG) crystal. As a result, the multi-beam pulsed 355 nm UV laser is successfully generated inside the THG crystal. The measured pulse widths of four sub-beams are shorter than 9 ns. Especially, the generated four sub-beams have good long-term power stability benefitting from the employed MLA. We believe that the generated stable multi-beam355 nm UV laser can meet the requirement of high-efficiency laser processing, and the presented method can also pave the way to generate stable and long-lived multi-beam UV lasers.
基金Agency for Science,Technology and Research(M22K2c0089)。
文摘We report the first demonstration of high-efficiency ultraviolet(UV)pulse generation in a resonance-free anti-resonant hollow-core fiber(AR-HCF).Using the wet-etching technique,we successfully reduced the cladding-tube wall thickness of the AR-HCF to 115 nm,thereby eliminating all cladding-induced structural resonances between the near-infrared pump and the deep UV wavelengths.This structural modification fundamentally suppresses competing conversion to other phase-matching points induced by structural resonances and mitigates the pump spectral broadening limitation,achieving a UV conversion efficiency as high as 12%—twice that of previous demonstrations in gas-filled AR-HCFs.This UV conversion efficiency is comparable to that of meter-scale gas-filled capillaries that require pump pulse energy of hundreds of microjoules while also maintaining the AR-HCF's inherent advantages of centimeter-scale compactness and low pump energy at the few microjoule level.
