We report on the fabrication of circular cladding waveguides with cross-section diameters of 60−120μm in Pr:YAG crystal by applying femtosecond laser inscription.The fabricated waveguides present 2D guidance on the c...We report on the fabrication of circular cladding waveguides with cross-section diameters of 60−120μm in Pr:YAG crystal by applying femtosecond laser inscription.The fabricated waveguides present 2D guidance on the cross-section and fairly low propagation losses.Multiple high-order guiding modes are observed in waveguides with different diameters.Corresponding simulation results reveal the origin of a specific kind of guiding modes.Confocal micro-Raman(μ-Raman)experiments demonstrate the modification effects in femtosecond laser affected areas and ascertain the refractive index induced guiding mechanism.In addition,luminescence emission properties of Pr3+ions at waveguide volume are well preserved during the femtosecond laser inscription process,which may result in a potential high-power visible waveguide laser.展开更多
We report on a diode-end-pumped high-power and high-energy Nd:YAG single-crystal fiber laser at 1834 nm.Two 808 nm diodes injecting about 58 W pump power into the Nd:YAG fiber have generated 3.28 W continuouswave and ...We report on a diode-end-pumped high-power and high-energy Nd:YAG single-crystal fiber laser at 1834 nm.Two 808 nm diodes injecting about 58 W pump power into the Nd:YAG fiber have generated 3.28 W continuouswave and 1.66 W Cr:ZnSe-based passively Q-switched lasers. Slope efficiencies with respect to pump powers are8.7% for the continuous-wave laser and 4.9% for the Q-switched laser. The extracted maximum pulse energy is about 266.9 μJ, and the corresponding maximum pulse peak power is 2.54 kW. These performances greatly surpass previous results regarding this specific laser emission because the laser gain medium in the form of fiber can significantly mitigate thermally induced power saturation thanks to its significantly reduced thermal lensing effect. Single-crystal fiber lasers show great potential for high average power, pulse energy, and peak power.展开更多
Main observation and conclusion In this article,we report a base-promoted sequential cyclization/aldol-type condensation/isomerization cascade reaction of N-propargyl-β-enaminones with aryl aldehydes.The key step in ...Main observation and conclusion In this article,we report a base-promoted sequential cyclization/aldol-type condensation/isomerization cascade reaction of N-propargyl-β-enaminones with aryl aldehydes.The key step in this protocol is the generation of 1,4-oxazepine anions from N-propargyl-β-enaminones under basic conditions,which are captured by aryl aldehydes.The method allows the formation of one pyridone core and one C—C double bond in“one pot”,and the preparation of a variety of densely decorated pyridone derivatives in moderate to good yields with broad functional group tolerance.展开更多
基金We are grateful for financial supports from National Natural Science Foundation of China(NSFC)(Grants No.61575097 and 11704201)National Natural Science Foundation of Tianjin City(NSFTJ)(17JCQNJC01600 and 19JCZDJC32700)the Fundamental Research Funds for the Central Universities.
文摘We report on the fabrication of circular cladding waveguides with cross-section diameters of 60−120μm in Pr:YAG crystal by applying femtosecond laser inscription.The fabricated waveguides present 2D guidance on the cross-section and fairly low propagation losses.Multiple high-order guiding modes are observed in waveguides with different diameters.Corresponding simulation results reveal the origin of a specific kind of guiding modes.Confocal micro-Raman(μ-Raman)experiments demonstrate the modification effects in femtosecond laser affected areas and ascertain the refractive index induced guiding mechanism.In addition,luminescence emission properties of Pr3+ions at waveguide volume are well preserved during the femtosecond laser inscription process,which may result in a potential high-power visible waveguide laser.
基金National Natural Science Foundation of China(NSFC)(61575164)Natural Science Foundation of Fujian Province of China(2018J01108)+2 种基金Principal Fund of Xiamen University(20720180082)Bulgarian National Science Fund(DNTS 01/9/2016)Science and Technology Plan Projects of Xuzhou,China(KC16HG232)
文摘We report on a diode-end-pumped high-power and high-energy Nd:YAG single-crystal fiber laser at 1834 nm.Two 808 nm diodes injecting about 58 W pump power into the Nd:YAG fiber have generated 3.28 W continuouswave and 1.66 W Cr:ZnSe-based passively Q-switched lasers. Slope efficiencies with respect to pump powers are8.7% for the continuous-wave laser and 4.9% for the Q-switched laser. The extracted maximum pulse energy is about 266.9 μJ, and the corresponding maximum pulse peak power is 2.54 kW. These performances greatly surpass previous results regarding this specific laser emission because the laser gain medium in the form of fiber can significantly mitigate thermally induced power saturation thanks to its significantly reduced thermal lensing effect. Single-crystal fiber lasers show great potential for high average power, pulse energy, and peak power.
文摘Main observation and conclusion In this article,we report a base-promoted sequential cyclization/aldol-type condensation/isomerization cascade reaction of N-propargyl-β-enaminones with aryl aldehydes.The key step in this protocol is the generation of 1,4-oxazepine anions from N-propargyl-β-enaminones under basic conditions,which are captured by aryl aldehydes.The method allows the formation of one pyridone core and one C—C double bond in“one pot”,and the preparation of a variety of densely decorated pyridone derivatives in moderate to good yields with broad functional group tolerance.
