Chirp Extraction of Self-Similar Pulses in a Passively Mode-Locked Er-doped Fiber Laser

In this paper, we adopt cloud computing in a specific scientific computing field for its virtualization, distribution and dynamic extendibility as follows: We obtain high-energy parabolic self-similar pulses by numerical simulation using our non-distributed passively mode-locked Er-doped fiber laser model. For researching characteristics of these wave-breaking-free self-similar pulses, chirp of them must be extracted. We propose several time-frequency analysis methods adopted in chirp extraction of ultra-short optical pulses for the first time and discuss the advantages and disadvantages of them in this particular application.

2.856 GHz microwave signal extraction from mode-locked Erfiber lasers with sub-100 femtosecond timing jitter

A balanced optical microwave phase detector(BOMPD) based on a 3 × 3 coupler is presented. This system was developed to extract ultra-low-jitter microwave signals from optical pulse trains emitted by mode-locked Er-fiber lasers, and synchronized microwave and laser systems. We demonstrate that the BOMPD achieves a precision of synchronization of less than 100 femtosecond of timing jitter. The experimental setup can be applied to the soft X-ray free-electron laser located on the campus of the Shanghai synchrotron radiation facility. A microwave signal with a 2.856 GHz frequency is extracted from a238 MHz mode-locked Er-laser, with an absolute timing jitter of 34 fs in the 10 Hz–10 MHz frequency offset range.In addition, the microwave and 238 MHz optical pulse signals are synchronized with a relative timing jitter of16 fs at the same frequency offset range.

Er∶YAG激光SWEEPS双脉冲模式激活荡洗在自由水域中的气泡动力学观测

目的:探究Er∶YAG激光光子增强的光声流(SWEEPS)技术在不同脉冲间隔参数条件下的蒸汽气泡动力学效应。方法:Er∶YAG激光手具连接工作尖放置于自由水域模型中,设置SWEEPS模式,150~600μs脉冲间隔激活。高速摄像机(200 000 Hz)摄录Er∶YAG激光激活荡洗引起空穴效应的过程,matlab逐帧分析蒸汽气泡间的相互作用关系,及蒸汽气泡消失时刻气泡残余与激光工作尖之间的距离。实验数据经SPSS 19.0统计软件进行统计分析。结果:在自由水域中,Er∶YAG激光SWEEPS模式下,脉冲间隔设置的改变会引起两次脉冲激发的蒸汽气泡形成不同的相互作用关系,包括双气泡融合、双气泡撞击及双气泡脱离。其中,脉冲间隔设置为360~440μs时,双气泡撞击现象会使蒸汽气泡消失时气泡残余与激光工作尖之间达到最远距离。结论:在自由水域中,Er∶YAG激光双脉冲SWEEPS模式在不同的脉冲间隔设置下引起双气泡间形成不同的作用关系,该现象可能可以增强Er∶YAG激光空穴效应,强化激光激活荡洗的临床应用效果。

2.79μm高速转镜调Q Er,Cr:YSGG纳秒窄脉冲激光器

转镜调Q无插入损耗,是获得窄脉冲、高峰值功率输出激光的直接方式。纳秒脉冲需要使用高速转镜调Q,并精准控制电机转速与氙灯放电延时,以使激光介质上能级粒子数反转最大,获得最大激光能量输出。本文设计了以Arduino mega 2560单片机为核心的高速转镜调Q控制系统,通过精确单片机解析串口屏指令控制激光电源的充放电和高速电机启停,同时通过对转镜脉冲信号整合降频控制氙灯放电时刻,实现对延迟时间的精准控制,实现了灯泵Er,Cr:YSGG激光纳秒窄脉冲调Q输出。在5 Hz重复频率下,转镜转速为650 r/s时,获得的最高单脉冲激光能量为45.7 mJ、脉冲宽度为86.2 ns,相应的峰值功率为530.2 kW。

基于石墨烯可饱和吸收体的Er∶YAG被动调Q激光器

本文研究了一种采用氙灯侧泵方式,并基于石墨烯可饱和吸收体的Er∶YAG被动调Q激光器。首先成功将石墨烯转移至Al_(2)O_(3)衬底制备得到石墨烯可饱和吸收体,并对其进行了形貌、结构及化学状态等性能表征。此外,对基于石墨烯可饱和吸收体的Er∶YAG被动调Q激光特性进行了研究,结果表明单脉冲能量从0.4 mJ增加至7 mJ,输出激光单脉冲宽度从761.2 ns下降至510 ns,最大峰值功率为13.7 kW。激光中心波长位于2935和2945 nm,且主波长在2935 nm处对应的半峰全宽(FWHM)为1.535 nm。沿x和y方向的光束质量因子分别为4.45和5.76。实验结果表明,该研究为推进更低成本、谐振腔设计简单且紧凑的2.94μm波段Er∶YAG激光器的发展提供了有效的参考依据。

热键合、凹端面及晶体棒直径对Er∶YSGG中红外激光性能的影响

对热键合、凹端面及不同直径Er∶YSGG晶体棒的中红外激光性能进行了系统对比研究。晶体经高温退火、定向切割、端面精密抛光后,测量得到其平面度和表面粗糙度分别小于0.1λ@633 nm和0.5 nm。通过精密加工实现了YSGG与Er∶YSGG室温光胶,然后进行了高温热键合,透过谱表明键合界面基本无损耗,达到了一体化。热焦距结果表明,热键合、凹端面能够有效改善和补偿高功率泵浦条件下晶体的热透镜效应,有利于提高晶体的激光性能。对比未键合、热键合及凹面热键合Er∶YSGG晶体在968 nm LD侧面泵浦条件下的激光性能发现,低频150 Hz以下,键合与凹面并未表现出优势,三种棒的最大输出功率和斜效率分别均在24 W和28%附近;但随重频增加,热效应逐渐加重,键合晶体良好散热能力和凹面热补偿效应使激光性能得到提高。在重频300 Hz下,未键合、热键合及凹面热键合三种棒的最大输出功率分别为15.54,17.85和18.33 W、斜效率分别为16.6%,18.3%和18.4%;重频600 Hz条件下,三种棒的最大输出功率分别为9.4,13.32和13.18 W、斜效率分别为6.7%,8.6%和9%。此外,对比研究了不同直径Er∶YSGG晶体的激光性能,在低于100 Hz的低频下,三种晶体的激光性能接近。但相比于3和4 mm键合凹面棒,直径2 mm棒有大的比表面积,拥有更好的热管理能力,使其在高重频条件下具有更好的激光性能。如在150 Hz条件下,2 mm凹面键合Er∶YSGG晶体棒获得了功率23.82 W、斜效率27.7%的中红外激光输出,大大高于直径3和4 mm棒的18 W和23%。在600 Hz,直径2 mm键合凹面棒中实现了功率13.18 W,斜效率9%的激光输出,相比于直径3和4 mm键合凹面棒的9 W,7%具有较大的改善。测量得到2 mm凹面键合Er∶YSGG晶体棒在150 Hz,200μs条件下的光束质量因子M_(x)^(2)/M_(y)^(2)=6.28/6.30,表明该激光具有良好的光束质量。综上,选择合适晶体棒直径,并将键合与凹面相结合是实现高性能2.79μm激光的有效方法。

3μm波段Er^(3+)∶ZBLAN光纤激光器研究进展及展望

3µm激光处于分子指纹区,在医疗外科、气体检测、军事应用等领域都有重要的应用价值。Er^(3+)∶ZBLAN光纤激光器具有效率高、可集成的优点,是3µm激光的主要输出方式。本文从铒离子跃迁产生3µm激光出发,围绕Er^(3+)∶ZBLAN光纤激光器,介绍了3µm激光产生的结构原理及能级系统,总结了实现该波段高功率连续输出和脉冲输出的技术方案和研究进展,重点介绍了基于不同材料可饱和吸收体的调Q和锁模激光器实验研究,并对目前实现3µm波段高功率输出需要解决的问题进行了分析,最后对Er^(3+)∶ZBLAN激光器的发展方向进行了展望。

Mid-infrared lightly Er^(3+)-doped CaF_(2)laser under acousto–optical modulation

A 1.7-at.%Er:CaF_(2)crystal was synthesized by temperature gradient method.The Er:CaF_(2)crystal was applied in acousto-optically Q-switched laser at mid-infrared region for the first time.Using a Te O_(2)-based crystal as Q-switcher,we obtained a laser diode(LD)end-pumped Er:CaF_(2)laser with the highest single pulse energy up to 0.49 mJ and maximum peak power of 0.56 kW under 6.34-W absorbed pump power.The implication of these results is that the low-doped Er:CaF_(2)crystal exhibits promising optical properties in solid-state lasers.

Nd∶YAG和Er∶YAG激光联合辅助治疗伴2型糖尿病的慢性牙周炎的临床疗效分析

纳入合并2型糖尿病的慢性牙周炎患者30例,采用分口设计法,将同患者左侧牙列设为试验组,行牙周基础治疗,以及Nd∶YAG和Er∶YAG激光联合辅助治疗,右侧牙列设为对照组,仅行牙周基础治疗。治疗前后检测牙周及CBCT影像指标,并行组间比较。治疗前2组全部指标无统计学差异(P>0.05)。治疗后3个月,试验组的出血指数(BI)和探诊深度(PD)明显低于对照组(P<0.05);治疗后6个月,试验组的BI、PD以及附着丧失(AL)明显低于对照组,牙槽骨内剩余牙根表面积和牙根体积明显高于对照组(P<0.05)。Nd∶YAG和Er∶YAG激光联合辅助下的牙周基础治疗较单纯牙周基础治疗对伴2型糖尿病的慢性牙周炎疗效更为显著。

Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体的光谱分析及中红外发射增强

采用非化学计量配比的提拉法成功生长出Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体、Er^(3+)/Yb^(3+):SrLaGaO_(4)和Er^(3+):SrLaGaO_(4)晶体并进行了详细的光谱分析,同时对纯的SrLaGaO_(4)晶体进行了热学性能分析。与Er^(3+):SrLaGaO_(4)晶体相比,Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体不仅展示了更好的吸收特性,而且还表现出较弱的近红外发射,以及优异的中红外发射;Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中2.7μm铒激光下能级4I13/2的荧光寿命显著减少,而上能级4I11/2的寿命略微下降,成功抑制了自终止效应。此外,本工作还研究了Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中Yb^(3+)的敏化作用和Pr^(3+)离子的去激活作用以及能量传递机制。总之,引入Yb^(3+)和Pr^(3+)有利于在Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中实现增强的2.7μm发射,这使其成为中红外激光有前途的候选材料。

准连续c切Er,Yb:YAl_(3)(BO_(3))_(4)激光器的偏振操控

通过构建谐振腔模型,分析了各向同性固体激光器中两个本征模式相干叠加后的光斑奇异特征。并且实验验证了在不使用任何特定的腔内光学偏振选择元件的情况下,在二极管泵浦的准连续c切Er,Yb:YAl_(3)(BO_(3))_(4)激光器中可以有效操控1.6μm输出激光的偏振态。实现了从部分偏振态转化成稳定的线偏振态,其线偏振方向为可切换的正交特殊情况,均具有21 dB的偏振消光比。同时通过光斑对比,验证了激光器的线偏振输出来源于两个正交本征模式的相干叠加。文中为c切Er,Yb:YAl_(3)(BO_(3))_(4)激光器线偏振光的直接输出与偏振态的调控提供了可靠的方案。

Er∶YAG激光应用于乳牙龋病的临床观察

目的观察Er∶YAG激光在乳牙龋病治疗中的临床疗效影响。方法选取60例于2023年2月至2023年5月在合肥市口腔医院儿童口腔科因乳牙龋病就诊的5~8岁患儿,随机分为两组,每组30例,实验组采用Er∶YAG激光处理,对照组采用传统高速涡轮机。分别采用面部图像量表(FIS量表)和Wong-Baker面部表情量表记录两组的焦虑、治疗时疼痛程度以及治疗时间。结果实验组焦虑、疼痛程度低于对照组(P<0.05),在治疗时间上差异无统计学意义(P>0.05)。结论在乳牙龋病治疗中,Er∶YAG激光较对照组更有利于缓解疼痛及焦虑状态。

超短脉冲激光在掺Er^(3+)磷酸盐玻璃中制备光波导的实验研究

超短脉冲激光通过非线性吸收调制光学材料折射率提供了一种高效制备集成三维光子器件的途径.掺Er^(3+)磷酸盐玻璃由于其优异的特性以及在1.55μm通信波段附近的发射光谱,成为了集成光学主动增益材料中的研究热点.实验采用重复频率1 kHz,中心波长800 nm,脉冲宽度120 fs的钛宝石飞秒激光放大系统作为制备波导的光源,系统研究了加工参数对激光写入形貌、波导形成及光学特性的影响.实验结果表明,在狭缝整形辅助短焦物镜横向刻写条件下,写入脉冲能量为1.8μJ时,光波导可以在写入速度为10μm/s-160μm的较宽范围内形成;写入速度为40μm/s时,光波导写入脉冲能量参数窗口为1.6μJ-2.0μJ;波导写入深度在125μm-200μm范围时,波导横截面对称性较好且折射率修改明显;近场强度测量结果显示所制备波导近场强度分布对称,导光特性良好.通过有限差分法反推波导区域折射率修改分布,结果显示最大折射率修改为Δn=6.6×10^(-4).截断传输损耗测量结果显示所制备波导的传输损耗低至0.91 dB/cm.

LD脉冲泵浦Er^(3+)/Yb^(3+):Lu_(2)Si_(2)O_(7)晶体百kHz激光器

目前1.5μm激光二极管(Laser Diode,LD)泵浦的铒镱共掺玻璃/晶体被动调Q微型激光器广泛应用于激光测距、激光雷达等领域。随着激光器输出重频的增加,玻璃面临突出的热效应问题,晶体的热导率是玻璃的10倍以上,有望能够实现比玻璃基质更高重频的激光输出。报道了一种通过LD脉冲端面泵浦Er^(3+)/Yb^(3+):Lu_(2)Si_(2)O_(7)晶体的百kHz人眼安全激光器。通过实验优化增益介质掺杂浓度和长度、泵浦光斑尺寸和调Q晶体初始透过率等实验参数,同时适当缩短脉宽,优化泵浦占空比,提高了输出重频的稳定性。最终获得了重频为100 kHz、单脉冲能量0.7μJ、脉冲宽度240 ns、光束质量M^(2)=1.61的1537 nm脉冲激光输出。实现了输出脉冲频率与泵浦的一致,保证了输出重频的稳定性,有效解决了输出重频具有随机性、不稳定、不可控等问题。

Self-starting all-fiber PM Er:laser mode locked by a biased nonlinear amplifying loop mirror

A compact all-fiber polarization-maintaining Er:laser using a nonlinear amplifying loop mirror is reported. Fundamental single-pulse mode-locking operation can always self start, with a cavity round-trip decreased from ~ 4.7 m to~ 1.7 m. When the pulse repetition rate is 121.0328 MHz, output pulse is measured to have a center wavelength/3-d B spectral bandwidth/radio frequency signal to noise ratio(SNR)/pulse width of 1571.65 nm/18.70 nm/80 d B/477 fs, respectively. Besides, three states including the exponential growth, damping state, and steady state are investigated through the build-up process both experimentally and numerically. Excellent stability of this compact Er:laser is further evaluated,demonstrating that it can be an easy-fabrication maintenance-free ultrafast candidate for the scientific area of this kind.

Noise-like rectangular pulses in a mode-locked double-clad Er:Yb laser with a record pulse energy

Generation of noise-like rectangular pulse was investigated systematically in an Er–Yb co-doped fiber laser based on an intra-cavity coupler with different coupling ratios.When the coupling ratio was 5/95,stable mode-locked pulses could be obtained with the pulse packet duration tunable from 4.86 ns to 80 ns.The repetition frequency was 1.186 MHz with the output spectrum centered at 1.6μm.The average output power and single pulse energy reached a record 1.43 W and1.21μJ,respectively.Pulse characteristics under different coupling ratios(5/95,10/90,20/80,30/70,40/60)were also presented and discussed.

44.6 fs pulses from a 257 MHz Er:fiber laser mode-locked by biased NALM

44.6 fs pulses from a 257 MHz, mode-locked non-polarization maintaining Er-doped fiber laser based on a biased nonlinear amplifying loop mirror are reported. The output power is 104 mW and the single-pulse energy is 0.4 nJ. The minimum pulse duration of the direct output is 44.6 fs, which is the shortest in this kind of laser.

Er∶YAG激光结合TheraCal LC直接盖髓术在龋源性露髓患牙中应用的研究

纳入深龋露髓患牙60颗,随机分为2组(n=30),分别行TheraCal直接盖髓术和TheraCal+Er∶YAG激光直接盖髓术。结果显示TheraCal+Er∶YAG激光组直接盖髓术术后12个月的成功率为96.7%,TheraCal组为73.3%(P<0.05)。Er∶YAG激光结合TheraCal LC盖髓剂可以显著提高龋源性露髓患牙直接盖髓术的成功率。

Influences of GVD on the characteristics of soliton in a passively mode-locked Er-doped fiber laser

In this paper, the characteristics of soliton in a passively mode-locked Er-doped fiber laser modeled by a non-distributed model are numerically investigated with the split-step Fourier method. Based on the analysis and model, sech2-shaped soliton is obtained by controlling the group velocity dispersion （GVD） and small-signal gain of the gain fiber. The law that the dispersion influences the characteristics of soliton in the mode-locked fiber laser is researched in net-cavity averaged anomalous dispersion regime.

Er^(3+),Yb^(3+)∶Ba_(3)Gd(PO_(4))_(3)晶体的生长、光谱和1.5μm激光性能

采用提拉法生长了1.85%Er,23.95%Yb∶Ba_(3)Gd(PO_(4))_(3)和1.95%Er,55.73%Yb∶Ba_(3)Gd(PO_(4))_(3)两种晶体(式中Er、Yb浓度为原子数分数)。测量并分析了晶体在室温下的吸收系数谱、上转换荧光谱、发射截面谱、增益截面谱和荧光衰减曲线。1.85%Er,23.95%Yb∶Ba_(3)Gd(PO_(4))_(3)晶体在峰值荧光波长1537 nm处的发射截面、Er^(3+)的4 I 13/2多重态荧光寿命和Yb^(3+)→Er^(3+)的能量传递效率分别为0.54×10^(-20)cm^(2)、9.9 ms和90%;1.95%Er,55.73%Yb∶Ba_(3)Gd(PO_(4))_(3)晶体在峰值荧光波长1537 nm处的发射截面、Er^(3+)的4 I 13/2多重态荧光寿命和Yb^(3+)→Er^(3+)的能量传递效率则分别为0.58×10^(-20)cm^(2)、9.7 ms和93%。基于975 nm半导体激光端面泵浦,在1.85%Er,23.95%Yb∶Ba_(3)Gd(PO_(4))_(3)晶体中实现了97 mW最高功率和27.1%斜效率的1567 nm连续激光输出,在1.95%Er,55.73%Yb∶Ba_(3)Gd(PO_(4))_(3)晶体中实现了93 mW最高功率和17.1%斜效率的1567 nm连续激光输出。