Dynamics of erbium-doped fibre laser with optical delay feedback and chaotic synchronization

The dynamical behaviour of the erbium-doped fibre single-ring laser with an optical delay feedback is discussed. Simulation shows that as the delay rate increases, the lasing light displays period-doubling which leads to chaos and via reverse period-doubling route returns from chaos to periodic. At a particular delay rate the intermittently chaotic route to chaos is also observed. The identical synchronization based on chaos in this ring laser is demonstrated by numerical simulation.

An experiment of dynamical behaviours in an erbium-doped fibre-ring laser with loss modulation

This paper reports a systematic experimental investigation on the dynamics in the low-frequency region in an erbium-doped fibre-ring laser with loss modulation. A rich variety of bifurcation is analyzed through the bifurcation diagram and structured with the concept of the winding numbers. The coexistence of multiple attractors and the crisis that appear in the saddle-node bifurcations, and an interesting structure of bifurcation which is similar to the bifurcations in high-frequency range, have been observed.

Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

We present a stable linear-cavity single longitudinal mode （SLM） erbium-doped silica fiber laser. It consists of four fiber Bragg gratings （FBGs） directly written in a section of photosensitive erbium-doped fiber （EDF） to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio （OSNR） of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer （OSA） for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.

Transition state to mode locking in a passively mode-locked erbium-doped fibre ring laser

The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.

Experimental investigation on chaos generation in erbium-doped fiber single-ring lasers

In this paper,the chaotic behaviors in an erbium-doped fiber（EDF） single-ring laser（EDFSRL） are investigated experimentally by using the loss modulation method.An electro-optic modulator（EOM） made of LiNbO 3 crystal is added to the system.Thus,by changing the modulation voltage and the modulation frequency of the EOM,the freedom of the EDFSRL system is increased.The chaotic characteristics of the system are studied by observing the time series and the power spectra.The experimental results indicate that the erbium-doped fiber single-ring laser system can enter into chaos states through period-doubling bifurcation and intermittency routes.

Analysis of New Q-switched Erbium Doped Fiber Laser Based on Fiber Grating Loop Mirror

An all fiber wavelength selective Q switching modulator based on fiber grating loop mirror is proposed. A newly configured Q switched erbium doped fiber laser using this all fiber modulator is numerically analyzed taking into account the effects of the spontaneous emission.

Erbium Doped Fiber Laser and Amplifier

In this paper, new configuration is proposed, investigated and analyzed. Fiber laser and fiber amplifier are merged in one configuration which called Erbium Doped Fiber Laser and Amplifier (EDFLA) or integrating EDFL and EDFA in one design. The configuration has three main outputs;one for laser, second for amplifier and the third it can be used for on/off output. A surprising phenomenon was remarked during the operation of this configuration. The amplification is abolished during the lasing state and appeared again if the lasing is stopped or the switch is off. The difference between outputs with the lasing and without lasing has 30 dB EDFA gain value;it is a good sign that this optical configuration can be used as an on/off integrated optical device for fiber laser.

Clinical study of treatment of facial scar with ultrapulse CO2 laser and Erbium fractional laser

Objective To observe the effect of uitrapulse CO2 laser combined with Erbium fractional laser on treatment facial scars. Methods Total 70 cases with facial scars were treated with ultrapulse CO2 laser combined with Erbium fractional laser for 3 times with 2 ～ 3 months interval. Firstly,scar resurfacing was performed

Passively Q-Switched Erbium-Doped Fiber Laser Based on GeSe Saturable Absorber

GeSe nanosheets were prepared by ultrasonic-assisted liquid phase exfoliation (LPE), and the nonlinear saturated absorption performance was experimentally studied. The modulation depth and saturation intensity of the prepared GeSe saturable absorber (SA) were 15% and 1.44 MW/cm2, respectively. Using the saturated absorption characteristics of GeSe SA, a passively Q-switched erbium-doped fiber laser was systematically demonstrated. As the pump power increases, the pulse repetition frequency increases from 22.8 kHz to 77.59 kHz. The shortest pulse duration is 1.51 μs, and the corresponding pulse energy is 46.14 nJ. Experimental results show that GeSe nanosheets can be used as high-efficiency SA in fiber lasers. Our results will provide a useful reference for demonstrating pulsed fiber lasers based on GeSe equipment.

点阵激光联合重组牛碱性细胞生长因子治疗皮脂腺增生62例疗效观察

目的观察Profile铒激光治疗皮脂腺增生的效果。方法对62例皮脂腺增生患者采用Profile超级平台铒激光模式进行治疗,并对资料进行回顾性分析。结果62例患者痊愈49例,显效11例,无效2例,总有效率为96.77%。术后瘢痕发生率为6.45%,3~6个月渐平复。暂时性色素改变1~3个月后均自行消退.随访6个月后治疗区未见复发。结论Profile铒激光治疗皮脂腺增生总体疗效较好,安全有效,不良反应小,值得临床推广应用。

Er:YAG激光和传统车针去龋后牙本质粘接强度的比较

目的:比较使用不同模式Er:YAG激光以及传统车针去龋后牙本质与复合树脂的粘接强度。方法:选用人类离体磨牙模拟龋坏,分别采用Er:YAG激光中短脉冲(medium short pulse,MSP)模式、Er:YAG激光超短脉冲(super short pulse,SSP)模式和传统车针去除模拟的龋坏后,采用自酸蚀粘接剂将牙体标本与复合树脂粘接制成试件。使用万能试验机对试件进行拉伸试验,测得断裂负荷和粘接强度,并采用单因素方差分析和Tukey多重比较进行统计学分析。采用扫描电子显微镜观察3种不同去龋方式处理后的牙本质表面形态,以及涂布自酸蚀粘接剂并固化后试件的横截面形态。结果:使用Er:YAG激光MSP模式处理后牙本质与复合树脂的粘接强度最高,SSP模式处理后次之,传统车针处理后最低,但差异无统计学意义(P>0.05)。扫描电子显微镜图像显示,Er:YAG激光MSP模式处理后的牙本质表面较平坦,牙本质小管内几乎没有残屑;Er:YAG激光SSP模式处理后的牙本质表面呈现鳞片状,牙本质小管内可见少量碎屑;而传统车针处理后牙本质小管大部分处于被表面牙本质部分甚至完全遮盖的状态,牙本质小管内充满残屑。结论:使用Er:YAG激光去龋相比传统车针去龋可以获得较好的牙本质粘接强度,且对牙本质小管的处理深度和洁净度明显优于传统车针去龋,其中MSP模式更佳。

不同强度铒激光荡洗活化对前磨牙根管内壁的清洗效果及根管硬度的影响

目的:探究不同强度铒激光(Er:YAG激光)荡洗活化对前磨牙根管内壁的清洗效果及根管硬度的影响。方法:根据铒激光荡洗强度不同将80例重度牙周炎患者拔除的137颗单根前磨牙分成实验A组、实验B组及对照组。A组采用0.2W Er:YAG激光荡洗,共45颗牙;B组采用0.3W Er:YAG激光荡洗,共42颗;对照组常规注射器头冲洗,共50颗牙。比较组间清洗后牙本质表面清洗效果、根尖渗透情况和根管硬度。结果:与对照组相比,A、B组的渗透距离更小(P<0.05),A组、B组两组间渗透距离无统计学差异(P>0.05)。A组、B组根颈/根中硬度均大于对照组(P<0.05),A组根尖部分硬度大于对照组(P<0.05),A、B两组根管硬度差异均无统计学意义(P>0.05)。B组玷污层戈夫曼玷污分级均低于对照组及A组(P<0.05)。结论:相较于常规注射器冲洗,铒激光荡洗活化可有效提高牙周炎前磨牙根管内壁的清洗效果,同时铒激光荡洗活化可减小对根管的损伤。0.3 W铒激光的清洗效果优于0.2 W,不同强度铒激光对根管硬度的影响较小。

掺铒CaF_(2)、SrF_(2)、PbF_(2)晶体的光谱性能与团簇结构研究

3μm波段中红外激光处于大气传输窗口,又可以作为基础光源,是激光技术研究的前沿。目前,铒离子激活的激光晶体材料是产生3μm中红外激光的重要途径之一。然而,Er3+离子4I11/2激光上能级荧光寿命较短,下能级4I13/2的寿命较长,难以实现粒子数反转,导致自终止现象。为了解决这一难题,往往需要高浓度掺杂,通过能量传递降低4I13/2能级的寿命。然而高浓度掺杂又会造成晶体热性能变差,限制了掺Er3+激光晶体效率和功率。三阶铒离子容易在氟化物晶体中形成团簇,导致稀土离子间距缩短,即使在低掺杂浓度下稀土离子之间的能量传递作用仍较为显著。同时,低浓度掺杂还可以减轻激光运转下晶体的热堆积效应。掺铒氟化物晶体已成为一类重要的高功率、高效率中红外激光材料。然而,掺铒氟化物晶体的光谱性能与铒离子团簇结构之间的相互联系尚不明确,制约了掺铒氟化物晶体光谱和激光性能的进一步发展。本文采用第一性原理计算模拟了铒离子在CaF_(2)、SrF_(2)和PbF_(2)晶体中的团簇结构。结果显示,铒离子团簇结构随基质晶体变化逐渐演变。结合模拟计算和实验表征定性揭示了不同晶体离子团簇与光谱性能的联系,为掺铒氟化物中红外激光晶体材料的调控与设计提供参考。

铒激光治疗对颌骨囊肿患者疗效、疼痛、舒适度、疼痛介质的影响

目的观察比较铒激光、传统方法对颌骨囊肿患者疗效、疼痛、舒适度、疼痛介质的影响。方法选取2018年10月—2022年10月收治的300例颌骨囊肿,根据手术方案分为铒激光组150例和传统组150例,分别采取铒激光治疗、传统刮治术治疗。统计2组围术期情况,治疗前后疼痛介质、口腔微生物群菌落数,以及术后舒适度、临床疗效、术后并发症。结果铒激光组术后24 h疼痛程度轻于传统组,术中出血量少于传统组,舒适度优于传统组(P<0.01);术后12 h铒激光组血清P物质、前列腺素E_(2)、神经肽Y水平低于传统组(P<0.05);术后3个月、6个月铒激光组双歧杆菌菌落数高于传统组,放线杆菌、牙龈卟啉单胞菌菌落数低于传统组(P<0.05);术后6个月2组治疗总有效率、术后并发症比较差异无统计学意义(P>0.05)。结论铒激光、传统方法在颌骨囊肿患者治疗中效果相当,铒激光治疗可减少患者术中出血量,缓解疼痛程度,维持口腔微生物群平衡,提高舒适度,减轻应激反应。

基于掺铒氟化物光纤的22.8μm可调谐激光输出

采用高浓度掺杂的掺铒氟化物光纤可以增强铒离子的能量转移上转换过程,从而产生2.8μm波段的中红外激光。铒离子的全波段发射光谱范围覆盖0.5~3.0μm,其发射波长与相应能级之间的跃迁相吻合。对铒离子全波段的激光输出开展了实验研究。由于氟化物掺铒光纤的高掺杂浓度, 2.8μm激光占据主导地位。当泵浦功率为2~4 W时,激光输出在2714~2784 nm范围内可调谐,这是由增益竞争和腔内选择性以及非均匀加宽效应造成的。当泵浦功率增加到3 W以上时,可以观察到激光的谱分裂现象。实验获得了2.8μm波段的高稳定中红外激光,最大输出功率为0.7 W,斜率效率为12%。

富血小板血浆联合2 940 nm点阵铒激光治疗女性型脱发的临床研究

目的:探讨富血小板血浆联合2 940 nm点阵铒激光治疗女性型脱发的临床疗效。方法:选取2022年5月-2023年5月天津市北辰医院皮肤科收治的90例女性型脱发患者分入A组、B组、C组,每组各30例。A组采用富血小板血浆联合2 940 nm点阵铒激光治疗,B组采用米诺地尔联合2 940 nm点阵铒激光治疗,C组采用2 940 nm点阵铒激光治疗。观察记录各组患者临床治疗疗效、满意度、不良反应以及治疗前后主观症状(油腻、瘙痒、头屑、脱发)、毛发镜指标(平均毛发密度、平均毳毛比例、平均毛干直径)情况。结果:A组患者临床治疗有效率(93.33%)明显高于B组(73.33%)、C组(66.67%)(P<0.05)。与治疗前比较,治疗后三组患者油腻、瘙痒、头屑、脱发主观症状评分均降低(P<0.05),且A组油腻、瘙痒、头屑、脱发主观症状评分低于B组、C组(P<0.05)。与治疗前比较,治疗后三组患者毳毛比例均降低,毛发密度、毛干直径均升高(P<0.05),且A组毳毛比例低于B组、C组,毛发密度、毛干直径高于B组、C组(P<0.05)。A组患者治疗后的总满意度(96.67%)明显高于B组(76.67%)、C组(73.33%)(P<0.05),但三组患者不良反应比较差异无统计学意义(P>0.05)。结论:富血小板血浆联合2 940 nm点阵铒激光治疗女性型脱发能取得较佳的临床疗效,可改善患者的头皮症状,增加毛发密度、毛干直径,同时安全性高,值得临床推广。

Lite Touch铒激光辅助治疗慢性牙周炎伴2型糖尿病的效果观察

目的:研究Lite Touch铒激光辅助治疗慢性牙周炎伴2型糖尿病的效果。方法:选取2021年1月—2022年12月内蒙古科技大学包头医学院第一附属医院口腔科收治的慢性牙周炎伴2型糖尿病患者60例患者作为研究对象,随机分为试验组与对照组,各30例。对照组进行牙周基础治疗,试验组在对照组基础上进行Lite Touch铒激光辅助治疗。比较两组牙周临床指标。结果:治疗前,两组菌斑指数(PLI)、探诊深度(PD)、附着丧失(CAL)及出血指数(BI)比较,差异无统计学意义(P>0.05);治疗后1、3个月,试验组PD、BI低于对照组,差异有统计学意义(P<0.05);治疗后1、3个月,两组PLI与CAL比较,差异无统计学意义(P>0.05);治疗后6个月,两组PLI比较,差异无统计学意义(P>0.05);治疗后6个月,试验组PD、CAL与BI低于对照组,差异有统计学意义(P<0.05)。结论:Lite Touch铒激光辅助治疗慢性牙周炎伴2型糖尿病的效果较好,能够优化牙周临床指标。

点阵铒激光联合外用生长因子凝胶治疗面部痤疮凹陷性瘢痕的临床效果观察

目的分析面部痤疮凹陷性瘢痕患者使用点阵铒激光联合外用生长因子凝胶的治疗效果。方法研究对象纳入2021年5月-2024年1月本院的74例面部痤疮凹陷性瘢痕患者,按照治疗方法不同将患者均分为对照组37例、观察组37例。对照组给予点阵铒激光治疗,观察组在对照组治疗的基础上给予外用生长因子凝胶治疗,两组都观察6周,记录临床效果。结果两组治疗6周后,总有效率对比发现,观察组(36/37)97.30%、对照组(30/37)81.08%,观察组较高(P<0.05)。两组结痂时间及痂皮脱落时间对比发现,观察组所用时间较对照组少(P<0.05)。两组治疗6周后,ECCA评分对比发现,治疗后较治疗前低,且观察组较对照组低(P<0.05)。两组治疗6周的皮肤含水量与治疗前相比显著增加(P<0.05),皮肤油脂含量与治疗前相比显著降低(P<0.05),观察组治疗6周后的皮肤含水量、皮肤油脂含量与对照组比较,差异有统计学意义(P<0.05)。结论在面部痤疮凹陷性瘢痕患者的治疗过程中使用点阵铒激光联合外用生长因子凝胶的治疗方法,能使结痂与痂皮脱落的时间缩短、治疗效果较高,还可缓解患者的临床症状,改善患者的皮肤屏障功能。

中红外掺铒氟化物光纤连续激光器及其数值分析

基于产生3μm中红外激光的Er^(3+)能量转换过程与能级体系,建立了掺铒氟化物光纤激光器的速率方程和传输方程,系统地研究了泵浦结构和光纤长度对输出功率、斜率效率以及腔内泵浦和激光功率分布的影响,为后续的实验提供理论依据。仿真确定了小泵浦功率的光纤激光器理想的光纤长度为4~8 m,最终实验选择4.7 m光纤完成了中红外掺铒氟化物光纤激光器连续激光输出光路的搭建,在泵浦功率为5 W、中心波长为2.797μm处实现了最大功率1.038 W、斜率效率20.4%的连续激光输出。

铒激光预处理对牙本质、牙釉质粘结强度及CAD/CAM玻璃陶瓷嵌体修复牙体缺损边缘微渗漏的影响

目的:探讨铒激光预处理对牙本质、牙釉质粘结强度及CAD/CAM玻璃陶瓷嵌体修复牙体缺损边缘微渗漏的影响。方法:收集2020年1月—2023年1月口腔外科门诊拔除的新鲜、无龋坏变色、无隐裂智齿62颗,根据预处理方式不同,随机分为铒激光组和磷酸组,每组31颗,每组再随机分为2份,分别用于粘结强度测试(16颗)和微渗漏测试(15颗)。比较2组牙釉质、牙本质抗剪切粘结强度和微渗漏程度及微渗漏评分分布情况。采用SPSS 17.0软件包对数据进行统计学分析。结果:铒激光组牙釉质、牙本质抗剪切粘结强度显著高于磷酸组(P<0.05);铒激光组侧壁、龈壁微渗漏程度显著低于磷酸组(P<0.05),铒激光组侧壁微渗漏评分主要为1分和2分,磷酸组侧壁微渗漏评分主要为2分,2组侧壁微渗漏评分分布相比,差异有统计学意义(P<0.05);铒激光组龈壁微渗漏评分主要为1分和2分,磷酸组龈壁微渗漏评分主要为2分和3分,2组龈壁微渗漏评分分布相比,差异有统计学意义(P<0.05)。结论:铒激光预处理可提高瓷嵌体与牙本质、牙釉质粘结强度,同时还可减少CAD/CAM玻璃陶瓷嵌体微渗漏,增强嵌体边缘密合性。