As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ene...As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ener-gy,biomedicine,optoelectronic devices,and so on.At present,there have been scant reports on the application of NiTe_(2)in the field of ultrafast photonics.In this work,NiTe_(2)was synthesized by chemical vapor deposition(CVD)and integrated with a tapered optical fiber to achieve mode-locking in an erbium-doped fiber laser(EDFL)and a thu-lium-doped fiber laser(TDFL).The mode-locked EDFL exhibited a pulse width of 678 fs and an output power of 3.92 mW.The pulse width of mode-locked TDFL was estimated to have a pulse width of 694 fs with an output power of 21.64 mW.These results demonstrate that NiTe_(2)is an effective saturable absorber material with potential applica-tions in the field of ultrafast optics.展开更多
In this paper,a conventional soliton(CS)mode-locked erbium-doped fiber(EDF)laser was de-veloped using MAX phase material(MAX-PM)Nb_(4)AlC_(3)as a saturable absorber(SA).First,the liquid phase exfoliation(LPE)method wa...In this paper,a conventional soliton(CS)mode-locked erbium-doped fiber(EDF)laser was de-veloped using MAX phase material(MAX-PM)Nb_(4)AlC_(3)as a saturable absorber(SA).First,the liquid phase exfoliation(LPE)method was utilized to prepare Nb_(4)AlC_(3)nanosheets,and then a piece of tapered fiber was adopted to fabricate Nb_(4)AlC_(3)-SA.It was found that the saturation intensity and modulation depth of the Nb_(4)AlC_(3)-SA are 2.02 MW/cm^(2)and 1.88%.Based on the Nb_(4)AlC_(3)-SA,a conventional soliton(CS)mode-locked EDF laser was achieved.The central wavelength,pulse duration,and pulse repetition rate were found to be 1565.65 nm,615.37 fs,and 24.63 MHz,respectively.The performance is competitive and particularly superior in terms of pulse duration.This study fully confirms that Nb_(4)AlC_(3)possesses marvellous nonlinear saturable absorption properties and opens new possibilities for further research on air-stable ultrafast photon-ic devices.展开更多
A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetr...A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.展开更多
The influence of different welding processes on the mechanical properties and the corresponding variation in the microstructural features have been investigated for the dissimilar weldments of 18% Ni maraging steel 25...The influence of different welding processes on the mechanical properties and the corresponding variation in the microstructural features have been investigated for the dissimilar weldments of 18% Ni maraging steel 250 and AISI 4130 steel. The weld joints are realized through two different fusion welding processes, tungsten inert arc welding(TIG) and laser beam welding(LBW), in this study. The dissimilar steel welds were characterized through optical microstructures, microhardness survey across the weldment and evaluation of tensile properties. The fiber laser beam welds have demonstrated superior mechanical properties and reduced heat affected zone as compared to the TIG weldments.展开更多
Fiber laser is the future development direction for the high energy lasers. This paper describs two kinds of optical coatings for fiber laser, including long and short wave pass filters. The one characteristic of fibe...Fiber laser is the future development direction for the high energy lasers. This paper describs two kinds of optical coatings for fiber laser, including long and short wave pass filters. The one characteristic of fiber laser coatings lies in that coatings should separate two closely wavelength light including laser pump wavelength (980 nm) and laser irradiation wavelength(1 050～1 100 nm). At the same time, the coatings should have high laser damage threshold.展开更多
A 2 kW single-mode fiber laser with two cascade home-made cladding light strippers(CLSs) has been demonstrated by employing bidirectional-pump scheme.2.009 k W signal power is obtained when pump power is 2.63 kW and t...A 2 kW single-mode fiber laser with two cascade home-made cladding light strippers(CLSs) has been demonstrated by employing bidirectional-pump scheme.2.009 k W signal power is obtained when pump power is 2.63 kW and the slope efficiency is 76.6%.Raman Stokes light is less than-47 d B at 2.009 kW even with a 10-m delivery fiber with core/inner cladding diameter of 20 mm/400 mm.The beam quality M^2≤1.2 and the spectral FWHM bandwidth is 4.34 nm.There is no transverse mode instability and the output power stability of ±0.14% is achieved by special thermal management for a more uniform temperature distribution on the Yb-doped gain fiber.展开更多
In order to improve ability of amplification about optical arrival angle in laser eavesdropping system, and enhance receiving field of view (FOV) of laser eavesdropping system, this paper presents a new multistage amp...In order to improve ability of amplification about optical arrival angle in laser eavesdropping system, and enhance receiving field of view (FOV) of laser eavesdropping system, this paper presents a new multistage amplifier laser eavesdropping model based on waveguide fiber taper. First of all, taking about four-quadrant (4QD) laser eavesdropping model as an example, from the theoretical view, analyses factors that, currently, laser eavesdropping system face many restrictive factors during practical applications. Besides, from the receiving FOV and ability of amplification about arrival angle of incoming optical axis angles, systematically analyses advantages of multi-stage amplifier model. What’s more,through constructing laser eavesdropping test platform, we demonstrate Signal to Noise Ratio(SNR) of two stage amplification model is eventually promoted to 6-10 dB compared with one amplifying model,especially in low and high audio level, the advantages is more obvious.展开更多
In this work,the generation of high signal-to-noise ratio(SNR)single-frequency microwave signal without noise sidebands is demonstrated based on the interaction of integrated all-fiber lasers.The microwave signals are...In this work,the generation of high signal-to-noise ratio(SNR)single-frequency microwave signal without noise sidebands is demonstrated based on the interaction of integrated all-fiber lasers.The microwave signals are generated by the interference between a narrow linewidth Brillouin pump light from a single-frequency laser and the Stokes light generated by it.Firstly,the linewidths of the Stokes lights are compressed to~43 Hz based on the stimulated Brillouin scattering(SBS)effect,which ensures that the frequency noise is as low as possible.And then,the relative intensity noise(RIN)of the first order Stokes light is reduced by 21 dB/Hz based on the noise dynamics principle in cascaded SBS effect.By simultaneously reducing the frequency noise and the intensity noise of the coherent signals,the noise sidebands of microwave signals are completely suppressed.As result,the SNR of the microwave signal is improved from 48 dB to 84 dB at the first-order Brillouin frequency shift of 9.415 GHz.Meanwhile,a microwave signal with a SNR of 70 dB is generated at the second-order Brillouin frequency shift of 18.827 GHz.This kind of microwave signals with narrow linewidth and high SNR can provide higher detection resolution and higher transmission efficiency for applications on radar,satellite communication and so on.展开更多
提出并验证了一种基于可调有源双耦合器环级联复合腔(Active dual-coupler ring based compound-cavity,ADCR-CC)滤波器的2μm波段单纵模(Single-longitudinal-mode,SLM)铥钬共掺光纤激光器。将具有可调滤波带宽和透射率的ADCR-CC滤波...提出并验证了一种基于可调有源双耦合器环级联复合腔(Active dual-coupler ring based compound-cavity,ADCR-CC)滤波器的2μm波段单纵模(Single-longitudinal-mode,SLM)铥钬共掺光纤激光器。将具有可调滤波带宽和透射率的ADCR-CC滤波器与光纤布拉格光栅(Fiber Bragg grating,FBG)结合,实现了SLM激光输出。当主腔和复合腔的泵浦功率分别为1.8 W和1.1 W时,测得的激光器输出波长为2048.510 nm,光信噪比高达83.08 dB,90 min内的最大光谱中心波长和光谱峰值功率波动分别为0.006 nm和0.19 dB,激光器输出功率为50.03 mW。使用等强度悬臂梁对FBG引入应变调节,SLM激光可在1.45 nm范围内实现波长的可调谐输出。展开更多
目的:评估采用光纤铥激光前列腺剜除术(thulium fiber laser enucleation of the prostate,ThuFLEP)治疗超大体积(>200 mL)前列腺的有效性和安全性。方法:回顾性分析2022年1月至2024年5月,于北京大学第一医院由同一泌尿外科医师进行...目的:评估采用光纤铥激光前列腺剜除术(thulium fiber laser enucleation of the prostate,ThuFLEP)治疗超大体积(>200 mL)前列腺的有效性和安全性。方法:回顾性分析2022年1月至2024年5月,于北京大学第一医院由同一泌尿外科医师进行手术的485例良性前列腺增生(benign prostatic hyperplasia,BPH)患者的临床资料,患者均采用光纤铥激光,根据前列腺总体积(total volume of the prostate,TPV)将患者分为三组:A组TPV<100 mL、B组100 mL≤TPV<200 mL、C组TPV≥200 mL。三组患者的年龄[(69.38±7.79)岁、(69.64±8.69)岁、(70.32±7.44)岁]、国际前列腺症状评分(International Prostate Symptom Score,IPSS)[(22.7±1.9)分、(22.8±2.7)分、(25.8±3.7)分]、最大尿流率(maximum urinary flow rate,Qmax)[(7.9±2.7)mL/s、(9.3±4.3)mL/s、(9.9±3.3)mL/s]差异均无统计学意义(P>0.05);三组患者的前列腺体积[(103.49±46.19)mL、(75.73±30.69)mL、(273.49±49.19)mL]、前列腺特异性抗原(prostate specific antigen,PSA)[3.52(1.05,8.76)μg/L、6.78(1.61,7.45)μg/L、8.52(5.05,12.76)μg/L]差异均有统计学意义(P<0.05)。结果:所有患者的手术均顺利完成,三组患者的剜除时间[30.0(21.2,44.5)min、41.6(31.2,52.5)min、45.1(35.2,50.0)min]、住院时间[(6.06±1.21)d、(6.15±1.50)d、(7.71±1.74)d]差异均无统计学意义(P>0.05);而三组患者的术后留置导尿管时间[(4.0±1.4)d、(4.0±1.3)d、(6.6±1.1)d]、手术时间[61(42,89)min、82(62,105)min、115(96,142)min]、剜除效率[1.29(0.71,1.56)g/min、1.67(1.23,2.15)g/min、2.74(2.20,3.34)g/min]、血红蛋白下降值[12(7,19)g/L、17(11,24)g/L、27(19,35)g/L]差异均有统计学意义(P<0.05)。线性回归分析显示,剜除效率与剜除重量之间存在较强的正向线性相关(r=0.880,P<0.001),剜除效率随着前列腺体积增加而提高。术后三组患者之间的IPSS[(6.6±1.7)分、(6.2±1.4)分、(4.6±1.1)分]、Qmax[(18.9±3.1)mL/s、(16.8±3.8)mL/s、(22.9±7.1)mL/s]差异均无统计学意义(P>0.05)。术后的IPSS、Qmax与术前比较差异均有统计学意义,但术后C组Qmax的提高明显高于其他两组(P<0.05)。术后并发症以Clavien-Dindo并发症系统评分为标准,分为Clavien-DindoⅠ(尿潴留、持续性血尿)、Clavien-DindoⅡ(腺体残余、泌尿系感染、输血)和Clavien-DindoⅢ(尿道狭窄、膀胱颈挛缩、出血并再次手术),三组患者术后均随访3个月,Clavien-Dindo的并发症发生率分别为5.2%(13例)、6.7%(12例)和12.1%(7例),组间差异有统计学意义(P<0.05),其中,泌尿系感染、输血及出血并再次手术的组间差异有统计学意义(P<0.05),其他并发症的组间差异无统计学意义(P>0.05)。结论:前列腺体积越大,输血及再次手术的风险增高,剜除效率随着前列腺体积的增加而提高,光纤铥激光前列腺剜除术治疗超大体积的BPH安全、有效。展开更多
基金Supported by Guangdong Basic and Applied Basic Research Fund,China(2024A1515012429)。
文摘As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ener-gy,biomedicine,optoelectronic devices,and so on.At present,there have been scant reports on the application of NiTe_(2)in the field of ultrafast photonics.In this work,NiTe_(2)was synthesized by chemical vapor deposition(CVD)and integrated with a tapered optical fiber to achieve mode-locking in an erbium-doped fiber laser(EDFL)and a thu-lium-doped fiber laser(TDFL).The mode-locked EDFL exhibited a pulse width of 678 fs and an output power of 3.92 mW.The pulse width of mode-locked TDFL was estimated to have a pulse width of 694 fs with an output power of 21.64 mW.These results demonstrate that NiTe_(2)is an effective saturable absorber material with potential applica-tions in the field of ultrafast optics.
文摘In this paper,a conventional soliton(CS)mode-locked erbium-doped fiber(EDF)laser was de-veloped using MAX phase material(MAX-PM)Nb_(4)AlC_(3)as a saturable absorber(SA).First,the liquid phase exfoliation(LPE)method was utilized to prepare Nb_(4)AlC_(3)nanosheets,and then a piece of tapered fiber was adopted to fabricate Nb_(4)AlC_(3)-SA.It was found that the saturation intensity and modulation depth of the Nb_(4)AlC_(3)-SA are 2.02 MW/cm^(2)and 1.88%.Based on the Nb_(4)AlC_(3)-SA,a conventional soliton(CS)mode-locked EDF laser was achieved.The central wavelength,pulse duration,and pulse repetition rate were found to be 1565.65 nm,615.37 fs,and 24.63 MHz,respectively.The performance is competitive and particularly superior in terms of pulse duration.This study fully confirms that Nb_(4)AlC_(3)possesses marvellous nonlinear saturable absorption properties and opens new possibilities for further research on air-stable ultrafast photon-ic devices.
文摘A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.
文摘The influence of different welding processes on the mechanical properties and the corresponding variation in the microstructural features have been investigated for the dissimilar weldments of 18% Ni maraging steel 250 and AISI 4130 steel. The weld joints are realized through two different fusion welding processes, tungsten inert arc welding(TIG) and laser beam welding(LBW), in this study. The dissimilar steel welds were characterized through optical microstructures, microhardness survey across the weldment and evaluation of tensile properties. The fiber laser beam welds have demonstrated superior mechanical properties and reduced heat affected zone as compared to the TIG weldments.
文摘Fiber laser is the future development direction for the high energy lasers. This paper describs two kinds of optical coatings for fiber laser, including long and short wave pass filters. The one characteristic of fiber laser coatings lies in that coatings should separate two closely wavelength light including laser pump wavelength (980 nm) and laser irradiation wavelength(1 050～1 100 nm). At the same time, the coatings should have high laser damage threshold.
基金China Postdoctoral Science Foundation Funded Project （2016M601253） Shenzhen Peacock Plan （KQCX2015033110182368） the project of Shenzhen Science and Technology Innovation Committee （JCYJ20160301114759922）.
文摘A 2 kW single-mode fiber laser with two cascade home-made cladding light strippers(CLSs) has been demonstrated by employing bidirectional-pump scheme.2.009 k W signal power is obtained when pump power is 2.63 kW and the slope efficiency is 76.6%.Raman Stokes light is less than-47 d B at 2.009 kW even with a 10-m delivery fiber with core/inner cladding diameter of 20 mm/400 mm.The beam quality M^2≤1.2 and the spectral FWHM bandwidth is 4.34 nm.There is no transverse mode instability and the output power stability of ±0.14% is achieved by special thermal management for a more uniform temperature distribution on the Yb-doped gain fiber.
基金Jilin province of Science and technology development plan key scientific and technological breakthrough project.(20150204083GX,20150204049GX)The 13th five-year science and technology research project of Jilin education department.(Jilin Provincial Education and technology system 2016357)Jilin provincial science and technology smes innovation fund.(20170308029HJ)
文摘In order to improve ability of amplification about optical arrival angle in laser eavesdropping system, and enhance receiving field of view (FOV) of laser eavesdropping system, this paper presents a new multistage amplifier laser eavesdropping model based on waveguide fiber taper. First of all, taking about four-quadrant (4QD) laser eavesdropping model as an example, from the theoretical view, analyses factors that, currently, laser eavesdropping system face many restrictive factors during practical applications. Besides, from the receiving FOV and ability of amplification about arrival angle of incoming optical axis angles, systematically analyses advantages of multi-stage amplifier model. What’s more,through constructing laser eavesdropping test platform, we demonstrate Signal to Noise Ratio(SNR) of two stage amplification model is eventually promoted to 6-10 dB compared with one amplifying model,especially in low and high audio level, the advantages is more obvious.
文摘In this work,the generation of high signal-to-noise ratio(SNR)single-frequency microwave signal without noise sidebands is demonstrated based on the interaction of integrated all-fiber lasers.The microwave signals are generated by the interference between a narrow linewidth Brillouin pump light from a single-frequency laser and the Stokes light generated by it.Firstly,the linewidths of the Stokes lights are compressed to~43 Hz based on the stimulated Brillouin scattering(SBS)effect,which ensures that the frequency noise is as low as possible.And then,the relative intensity noise(RIN)of the first order Stokes light is reduced by 21 dB/Hz based on the noise dynamics principle in cascaded SBS effect.By simultaneously reducing the frequency noise and the intensity noise of the coherent signals,the noise sidebands of microwave signals are completely suppressed.As result,the SNR of the microwave signal is improved from 48 dB to 84 dB at the first-order Brillouin frequency shift of 9.415 GHz.Meanwhile,a microwave signal with a SNR of 70 dB is generated at the second-order Brillouin frequency shift of 18.827 GHz.This kind of microwave signals with narrow linewidth and high SNR can provide higher detection resolution and higher transmission efficiency for applications on radar,satellite communication and so on.
