The chemiluminescence spectrum in the optical cavity of discharge-driven hydrogen fluoride (HF) chemical laser is measured. The result reveals that the spectra of the helium and fluorine (F) atoms are the major co...The chemiluminescence spectrum in the optical cavity of discharge-driven hydrogen fluoride (HF) chemical laser is measured. The result reveals that the spectra of the helium and fluorine (F) atoms are the major components. Moreover, the green chemiluminescence in the downstream of the optical axis is mostly composed of the 60P20 spectral line of the HF molecule. The analysis shows that, except for the cold pumping reaction, the recombination of the F atoms and the hot pumping reaction also occur in the optical cavity. Due to the hot pumping reaction and the opticM cavity temperature in a specific range, the 60P20 line becomes the strongest HF molecule in the downstream region of the optical axis. After the hot pumping reaction, the green chemiluminescence always appears in the downstream region of the optical axis when the optical cavity temperature varies in a ~reater ran~.展开更多
Laser performance is greatly dependent on its operating conditions due to the strong coupling among multi- physics such as gas-dynamics, chemical reaction kinetics and optics in the mixing nozzle of COIL. In this pape...Laser performance is greatly dependent on its operating conditions due to the strong coupling among multi- physics such as gas-dynamics, chemical reaction kinetics and optics in the mixing nozzle of COIL. In this paper, 3D CFD technology is used to simulate the mixing and reactive flow of subsonic cross jet scheme at different conditions. Results obtained show that the jet penetration depth plays a dominant role in the spatial distribution of small signal gains. In the case of over-penetration, unsteady flow structures are induced by impinging between the opposing jets. The optimum spatial distribution of the chemical performance cannot be obtained even if the full penetration condition is achieved through the subsonic transverse jet mixing scheme in the COIL nozzle flow.展开更多
We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the c...We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the chemical reaction of the femtosecond laser-induced structure change zone and hydrofluoric acid solution. The morphologies of the through micro-holes and micro-hole arrays are characterized by using scanning electronic microscopy, The effects of the pulse number on the depth and diameter of the holes are investigated. Honeycomb arrays of through micro-holes fabricated at different laser powers and pulse numbers are demonstrated.展开更多
Electrospray,as a liquid source supply system,has been applied to chemical vapour deposition(CVD).In thermal CVD,the microstructure of the obtained films changes from dense to coarse granular because of the decreasi...Electrospray,as a liquid source supply system,has been applied to chemical vapour deposition(CVD).In thermal CVD,the microstructure of the obtained films changes from dense to coarse granular because of the decreasing surface temperature during deposition.Using the electrospray laser chemical vapour deposition method,we prepared homogenous alumina coatings.We found that laser irradiation was effective in compensating the surface temperature decrease,and an alpha-alumina coating with dense columnar microstructures was obtained at a deposition rate of 200 μm/h using 200 W Nd:YAG laser irradiation.展开更多
We report an erbium-doped fiber laser passively Q-switched by a few-layer molybdenum disulfide(MoS2) saturable absorber(SA).The few-layer MoS2 is grown by the chemical vapor deposition method and transferred onto ...We report an erbium-doped fiber laser passively Q-switched by a few-layer molybdenum disulfide(MoS2) saturable absorber(SA).The few-layer MoS2 is grown by the chemical vapor deposition method and transferred onto the end-face of a fiber connector to form a fiber-compatible MoS2 SA.The laser cavity is constructed by using a three-port optical circulator and a fiber Bragg grating(FBG) as the two end-mirrors.Stable Q-switched pulses are obtained with a pulse duration of 1.92 μs at 1560.5 nm.By increasing the pump power from 42 to 204 mW,the pulse repetition rate can be widely changed from 28.6 to 114.8 kHz.Passive Q-switching operations with discrete lasing wavelengths ranging from 1529.8 to 1570.1 nm are also investigated by using FBGs with different central wavelengths.This work demonstrates that few-layer MoS2 can serve as a promising SA for wideband-tunable Q-switching laser operation.展开更多
A superhard α-Si_3N_4 film,deposited on metal substrate,was produced by laser chemical vapor deposition adopting a kW-level high power CO_2 laser.Most films are composed of fine Si_3N_4 partieles.They join the metal ...A superhard α-Si_3N_4 film,deposited on metal substrate,was produced by laser chemical vapor deposition adopting a kW-level high power CO_2 laser.Most films are composed of fine Si_3N_4 partieles.They join the metal substrate in strong bond.The films have super hardness,excellent resistance to wear and corrosion,etc.Their thickness may be controlled within 5-30 μm.展开更多
We report the superior stability of the composite Cs2CO3 :Ag/Ag cathode structure, which can be used in efficient organic light-emitting diodes (OLEDs). Devices with the Cs2CO3:Ag (1:10, 5nm)/Ag (95nm) cathod...We report the superior stability of the composite Cs2CO3 :Ag/Ag cathode structure, which can be used in efficient organic light-emitting diodes (OLEDs). Devices with the Cs2CO3:Ag (1:10, 5nm)/Ag (95nm) cathode show a considerably improved lifetime compared with the control device with the Cs2CO3 (0.5 nm)/Ag (100 nm) cathode. The composite Cs2CO3 :Ag/Ag film is proved to be stable in the atmosphere. X-ray diffraction (XRD) is applied to analyze the crystalline structure of the Cs2CO3:Ag film, and it is demonstrated that CsAg alloy is formed, leading to the improved stability of the thin film and the devices.展开更多
Azobenzene polymer films doped with and without Ag nanoparticles are prepared. The photoinduced reorientation process is investigated by using an Nd:YVO4 pump beam at 532 nm and a low semiconductor laser beam at 650 ...Azobenzene polymer films doped with and without Ag nanoparticles are prepared. The photoinduced reorientation process is investigated by using an Nd:YVO4 pump beam at 532 nm and a low semiconductor laser beam at 650 nm. The reorientation rate of azo polymer films is enhanced in the presence of Ag nanoparticles, and the rate of the azo polymer film with Ag concentration of 2.2 μg/ml is larger than that of the azo polymer films with Ag concentrations of 1.1 μg/ml and 4.4 μg/ml. The third-order nonlinear optical properties of the Ag/azo composite film are obtained by the Z-scan technique at a wavelength of 532 nm, and the measured nonlinear refractive index is 9.258×10-9 esu. It is shown that the main mechanisms involved in the large nonlinear optical responses come from the local field enhancement of Ag nanoparticles and the nonlinear effect of the azo polymer matrix.展开更多
A phase retarder used in chemical oxygen-iodine laser (COIL) system has been fabricated by ion beam sputtering (IBS). When the incident angle is 45°the reflectivity is about 99.9% from 1290 to 1340 nm and abo...A phase retarder used in chemical oxygen-iodine laser (COIL) system has been fabricated by ion beam sputtering (IBS). When the incident angle is 45°the reflectivity is about 99.9% from 1290 to 1340 nm and about 83.8% at 632.8 nm, and the phase retardance between the parallel and perpendicular polarization components is -92.8°at 1315 nm. In order to get the influence of temperature on the phase retarder, six samples have been annealed from 523 to 648 K at interval of 25 K in air respectively, and the results show good temperature performance, With increasing temperature phase retardance becomes smaller, and the variation is within 4° at 1315 nm. At the same time, the variation maintains within ±10° for the incidence from 44°to 49°.展开更多
TiO_(2) thin films were prepared on Pt/Ti/SiO_(2)/Si substrate by laser chemical vapor deposition(LCVD)method.The effects of laser power(P_(L))and total pressure(p_(tot))on the microstructure of TiO_(2) thin films wer...TiO_(2) thin films were prepared on Pt/Ti/SiO_(2)/Si substrate by laser chemical vapor deposition(LCVD)method.The effects of laser power(P_(L))and total pressure(p_(tot))on the microstructure of TiO_(2) thin films were investigated.The deposition temperature(T_(dep))was mainly affected by P_(L),increasing with P_(L) increasing.The single-phase rutile TiO_(2) thin films with different morphologies were obtained.The morphologies of TiO_(2) thin films were classified into three typical types,including the powdery,Wulff-shaped and granular microstructures.p_(tot) and T_(dep) were the two critical factors that could be effectively used for controlling the morphology of the films.展开更多
A pulsed chemical oxygen-iodine laser (COIL) using atomic iodine generated by volumetric discharge of CHaI is developed and tested. COIL with a gain length of 60 cm is energized by a square pipe-array jet singlet ox...A pulsed chemical oxygen-iodine laser (COIL) using atomic iodine generated by volumetric discharge of CHaI is developed and tested. COIL with a gain length of 60 cm is energized by a square pipe-array jet singlet oxygen generator with basic hydrogen peroxide pumping circulations and operated at subsonic gas flow. Maximum output energy of 4.3 J, pulse duration of 50 #s, specific energy extraction from the active medium of 2.0 J/L, and the maximum chemical efficiency of 12.5% are achieved at a chlorine flow rate of 55 mmole/s.展开更多
TiO_(2)-rich Ba-Ti-O films were prepared on Pt/Ti/SiO_(2)/Si substrate by laser chemical vapor deposition(LCVD).Their phase relationship and microstructure were investigated.The single-phase BaTi_(2)O_(5),Ba_(4)Ti_(13...TiO_(2)-rich Ba-Ti-O films were prepared on Pt/Ti/SiO_(2)/Si substrate by laser chemical vapor deposition(LCVD).Their phase relationship and microstructure were investigated.The single-phase BaTi_(2)O_(5),Ba_(4)Ti_(13)O_(3)0 and BaTi_(5)O_(11) films were prepared at Ti/Ba molar ratios m_(Ti/Ba)=1.84-1.90,2.83 and 4.49-4.55,respectively.The high deposition rate of TiO_(2)-rich Ba-Ti-O films ranged from 54.0μm/h to 177.6μm/h.The permittivity of BaTi_(2)O_(5)film(prepared at m_(Ti/Ba)=1.84 and deposition temperature T_(dep)=877 K),Ba_(4)Ti_(13)O_(3)0 film(prepared at m_(Ti/Ba)=2.83 and T_(dep)=914 K)and BaTi5O11 film(prepared at m_(Ti/Ba)=4.49 and T_(dep)=955 K)were 50,40 and 21,respectively.展开更多
Silver nanoparticles in the range of 10-40 nm were synthesized chemically and by laser ablation, em- ployed for in vitro antibacterial action against human pathogenic bacterium. Their formation was evidenced by UV-vis...Silver nanoparticles in the range of 10-40 nm were synthesized chemically and by laser ablation, em- ployed for in vitro antibacterial action against human pathogenic bacterium. Their formation was evidenced by UV-visible spectrophotometer; particle size confirmed by atomic force microscopy, crystal structure determined by X-ray diffraction and chemical composition investigated by Fourier transform infrared spec- troscopy. The calculated MIC (minimum inhibitory concentration) of chemically synthesized nanoparticles with 30-40 nm in size are 2.8 μg/mL 4.37 μg/mL 13.5μg/mL and 2.81 p.g/mL for E. coil, S. aureus, B. subtillis and Salmonella, respectively. Whereas laser ablated nanoparticles exhibit MIC of 2.10 μg/mL 2.36 μg/ mL and 2.68 μg/mL for E. coli, S. aureus and Salmonella, respectively.展开更多
A Closed Cavity measuring platform is built on the basis of a 1000 W-class direct current (DC)-discharge drived con- tinuous-wave (CW) HF/DF chemical laser. On this platform, the absorption coefficients of optical...A Closed Cavity measuring platform is built on the basis of a 1000 W-class direct current (DC)-discharge drived con- tinuous-wave (CW) HF/DF chemical laser. On this platform, the absorption coefficients of optical thin films coated on the surfaces of monocrystalline silicon substrates, at the wavelength of 3.6-4.1 μm, is measured, when the power density on the surfaces of optical thin films reaches about 3.16 kW/cm^2. The measuring principle and structure of the Closed Cavity is introduced. The temperature curves and balanced temperature rises of the film-suN strate systems under test measured through the experiment is presented in this Letter. The experiments show high reliability, good repeatability and strong practicality. The Closed Cavity measuring platform is applicable for not only absorption measurement but other performance measurement of optical thin films under high power density.展开更多
文摘The chemiluminescence spectrum in the optical cavity of discharge-driven hydrogen fluoride (HF) chemical laser is measured. The result reveals that the spectra of the helium and fluorine (F) atoms are the major components. Moreover, the green chemiluminescence in the downstream of the optical axis is mostly composed of the 60P20 spectral line of the HF molecule. The analysis shows that, except for the cold pumping reaction, the recombination of the F atoms and the hot pumping reaction also occur in the optical cavity. Due to the hot pumping reaction and the opticM cavity temperature in a specific range, the 60P20 line becomes the strongest HF molecule in the downstream region of the optical axis. After the hot pumping reaction, the green chemiluminescence always appears in the downstream region of the optical axis when the optical cavity temperature varies in a ~reater ran~.
基金the Korea Research Foundation Grant No.KRF-2005-005-J09901
文摘Laser performance is greatly dependent on its operating conditions due to the strong coupling among multi- physics such as gas-dynamics, chemical reaction kinetics and optics in the mixing nozzle of COIL. In this paper, 3D CFD technology is used to simulate the mixing and reactive flow of subsonic cross jet scheme at different conditions. Results obtained show that the jet penetration depth plays a dominant role in the spatial distribution of small signal gains. In the case of over-penetration, unsteady flow structures are induced by impinging between the opposing jets. The optimum spatial distribution of the chemical performance cannot be obtained even if the full penetration condition is achieved through the subsonic transverse jet mixing scheme in the COIL nozzle flow.
基金Supported by the National Basic Research Program of China under Grant No 2012CB921804the National Natural Science Foundation of China under Grant Nos 11204236 and 61308006the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the chemical reaction of the femtosecond laser-induced structure change zone and hydrofluoric acid solution. The morphologies of the through micro-holes and micro-hole arrays are characterized by using scanning electronic microscopy, The effects of the pulse number on the depth and diameter of the holes are investigated. Honeycomb arrays of through micro-holes fabricated at different laser powers and pulse numbers are demonstrated.
文摘Electrospray,as a liquid source supply system,has been applied to chemical vapour deposition(CVD).In thermal CVD,the microstructure of the obtained films changes from dense to coarse granular because of the decreasing surface temperature during deposition.Using the electrospray laser chemical vapour deposition method,we prepared homogenous alumina coatings.We found that laser irradiation was effective in compensating the surface temperature decrease,and an alpha-alumina coating with dense columnar microstructures was obtained at a deposition rate of 200 μm/h using 200 W Nd:YAG laser irradiation.
基金supported by the National Natural Science Foundation of China (Grant Nos.61378028,61475030,61421002,and 61377037)the National Basic Research Program of China (2012CB315701)the NCET Program (Grant No.NCET-13-0092)
文摘We report an erbium-doped fiber laser passively Q-switched by a few-layer molybdenum disulfide(MoS2) saturable absorber(SA).The few-layer MoS2 is grown by the chemical vapor deposition method and transferred onto the end-face of a fiber connector to form a fiber-compatible MoS2 SA.The laser cavity is constructed by using a three-port optical circulator and a fiber Bragg grating(FBG) as the two end-mirrors.Stable Q-switched pulses are obtained with a pulse duration of 1.92 μs at 1560.5 nm.By increasing the pump power from 42 to 204 mW,the pulse repetition rate can be widely changed from 28.6 to 114.8 kHz.Passive Q-switching operations with discrete lasing wavelengths ranging from 1529.8 to 1570.1 nm are also investigated by using FBGs with different central wavelengths.This work demonstrates that few-layer MoS2 can serve as a promising SA for wideband-tunable Q-switching laser operation.
文摘A superhard α-Si_3N_4 film,deposited on metal substrate,was produced by laser chemical vapor deposition adopting a kW-level high power CO_2 laser.Most films are composed of fine Si_3N_4 partieles.They join the metal substrate in strong bond.The films have super hardness,excellent resistance to wear and corrosion,etc.Their thickness may be controlled within 5-30 μm.
文摘We report the superior stability of the composite Cs2CO3 :Ag/Ag cathode structure, which can be used in efficient organic light-emitting diodes (OLEDs). Devices with the Cs2CO3:Ag (1:10, 5nm)/Ag (95nm) cathode show a considerably improved lifetime compared with the control device with the Cs2CO3 (0.5 nm)/Ag (100 nm) cathode. The composite Cs2CO3 :Ag/Ag film is proved to be stable in the atmosphere. X-ray diffraction (XRD) is applied to analyze the crystalline structure of the Cs2CO3:Ag film, and it is demonstrated that CsAg alloy is formed, leading to the improved stability of the thin film and the devices.
文摘Azobenzene polymer films doped with and without Ag nanoparticles are prepared. The photoinduced reorientation process is investigated by using an Nd:YVO4 pump beam at 532 nm and a low semiconductor laser beam at 650 nm. The reorientation rate of azo polymer films is enhanced in the presence of Ag nanoparticles, and the rate of the azo polymer film with Ag concentration of 2.2 μg/ml is larger than that of the azo polymer films with Ag concentrations of 1.1 μg/ml and 4.4 μg/ml. The third-order nonlinear optical properties of the Ag/azo composite film are obtained by the Z-scan technique at a wavelength of 532 nm, and the measured nonlinear refractive index is 9.258×10-9 esu. It is shown that the main mechanisms involved in the large nonlinear optical responses come from the local field enhancement of Ag nanoparticles and the nonlinear effect of the azo polymer matrix.
文摘A phase retarder used in chemical oxygen-iodine laser (COIL) system has been fabricated by ion beam sputtering (IBS). When the incident angle is 45°the reflectivity is about 99.9% from 1290 to 1340 nm and about 83.8% at 632.8 nm, and the phase retardance between the parallel and perpendicular polarization components is -92.8°at 1315 nm. In order to get the influence of temperature on the phase retarder, six samples have been annealed from 523 to 648 K at interval of 25 K in air respectively, and the results show good temperature performance, With increasing temperature phase retardance becomes smaller, and the variation is within 4° at 1315 nm. At the same time, the variation maintains within ±10° for the incidence from 44°to 49°.
基金This work was supported in part by the Global COE Program of the Materials Integration,Tohoku University,and the International Science and Technology Cooperation Program of China(Grant No.2009DFB50470)This work was also supported in part by the International Science and Technology Cooperation Project of Hubei Province(Grant No.2010BFA017)and the 111 Project of China(Grant No.B13035).
文摘TiO_(2) thin films were prepared on Pt/Ti/SiO_(2)/Si substrate by laser chemical vapor deposition(LCVD)method.The effects of laser power(P_(L))and total pressure(p_(tot))on the microstructure of TiO_(2) thin films were investigated.The deposition temperature(T_(dep))was mainly affected by P_(L),increasing with P_(L) increasing.The single-phase rutile TiO_(2) thin films with different morphologies were obtained.The morphologies of TiO_(2) thin films were classified into three typical types,including the powdery,Wulff-shaped and granular microstructures.p_(tot) and T_(dep) were the two critical factors that could be effectively used for controlling the morphology of the films.
文摘A pulsed chemical oxygen-iodine laser (COIL) using atomic iodine generated by volumetric discharge of CHaI is developed and tested. COIL with a gain length of 60 cm is energized by a square pipe-array jet singlet oxygen generator with basic hydrogen peroxide pumping circulations and operated at subsonic gas flow. Maximum output energy of 4.3 J, pulse duration of 50 #s, specific energy extraction from the active medium of 2.0 J/L, and the maximum chemical efficiency of 12.5% are achieved at a chlorine flow rate of 55 mmole/s.
基金This work was supported in part by the Global COE Program of the Materials Integration,Tohoku Universityby the International Science and Technology Cooperation Program of China(Grant No.2009DFB50470).
文摘TiO_(2)-rich Ba-Ti-O films were prepared on Pt/Ti/SiO_(2)/Si substrate by laser chemical vapor deposition(LCVD).Their phase relationship and microstructure were investigated.The single-phase BaTi_(2)O_(5),Ba_(4)Ti_(13)O_(3)0 and BaTi_(5)O_(11) films were prepared at Ti/Ba molar ratios m_(Ti/Ba)=1.84-1.90,2.83 and 4.49-4.55,respectively.The high deposition rate of TiO_(2)-rich Ba-Ti-O films ranged from 54.0μm/h to 177.6μm/h.The permittivity of BaTi_(2)O_(5)film(prepared at m_(Ti/Ba)=1.84 and deposition temperature T_(dep)=877 K),Ba_(4)Ti_(13)O_(3)0 film(prepared at m_(Ti/Ba)=2.83 and T_(dep)=914 K)and BaTi5O11 film(prepared at m_(Ti/Ba)=4.49 and T_(dep)=955 K)were 50,40 and 21,respectively.
文摘Silver nanoparticles in the range of 10-40 nm were synthesized chemically and by laser ablation, em- ployed for in vitro antibacterial action against human pathogenic bacterium. Their formation was evidenced by UV-visible spectrophotometer; particle size confirmed by atomic force microscopy, crystal structure determined by X-ray diffraction and chemical composition investigated by Fourier transform infrared spec- troscopy. The calculated MIC (minimum inhibitory concentration) of chemically synthesized nanoparticles with 30-40 nm in size are 2.8 μg/mL 4.37 μg/mL 13.5μg/mL and 2.81 p.g/mL for E. coil, S. aureus, B. subtillis and Salmonella, respectively. Whereas laser ablated nanoparticles exhibit MIC of 2.10 μg/mL 2.36 μg/ mL and 2.68 μg/mL for E. coli, S. aureus and Salmonella, respectively.
基金supported by the National Natural Science Foundation of China under Grant Nos.10304025 and 10974255
文摘A Closed Cavity measuring platform is built on the basis of a 1000 W-class direct current (DC)-discharge drived con- tinuous-wave (CW) HF/DF chemical laser. On this platform, the absorption coefficients of optical thin films coated on the surfaces of monocrystalline silicon substrates, at the wavelength of 3.6-4.1 μm, is measured, when the power density on the surfaces of optical thin films reaches about 3.16 kW/cm^2. The measuring principle and structure of the Closed Cavity is introduced. The temperature curves and balanced temperature rises of the film-suN strate systems under test measured through the experiment is presented in this Letter. The experiments show high reliability, good repeatability and strong practicality. The Closed Cavity measuring platform is applicable for not only absorption measurement but other performance measurement of optical thin films under high power density.