LD泵浦的1.3at.%Er^(3+):CaF_(2)中红外高功率固体激光器(特邀)

3μm波段激光是高精度外科手术的理想光源,也可作为长波中红外光参量振荡器的有效泵浦源。LD直接泵浦Er^(3+)掺杂晶体是获得2.7~3μm波段中红外激光的有效技术途径,具有成本低、结构紧凑简单等优点。由于Er^(3+)2.8μm激光下能级阻塞问题,一般需要高浓度掺杂,但高浓度掺杂易引起强烈的光吸收,增强了激光晶体的热效应,从而阻碍了激光功率的提升。低声子能量的氟化钙晶体特有的萤石型结构使得三价稀土离子极易形成"团簇",将低浓度Er^(3+)掺杂到氟化钙晶体中即可获得高效率的中红外激光增益介质。笔者课题组使用温度梯度法成功生长了低浓度掺杂1.3at.%Er^(3+):CaF_(2)激光晶体,利用LD直接泵浦获得了2.2 W的中红外激光输出,这是目前利用LD端面泵浦同类晶体中的最高中红外激光输出功率。同时,文中还对上转换泵浦方式下该晶体的2.8μm激光特性进行了研究。实验结果表明,低浓度掺杂的1.3at.%Er^(3+):CaF_(2)晶体是一类具有产业化前景的中红外激光材料,有望推动长波中红外激光器向着结构紧凑、成本低的方向发展。

基于铋纳米片可饱和吸收被动调Q中红外单晶光纤激光器

铋纳米片作为一种新型二维材料,具有合适的带隙、较高的载流子迁移率和较好的室温稳定性,加上优异的电学和光学特性,是实现中红外脉冲激光的有效调制器件.中红外单晶光纤兼备晶体和光纤的优势,是实现高功率激光的首选增益介质.本文采用超声波法成功制备了铋纳米片可饱和吸收体,并首次将其用于二极管抽运Er:CaF2单晶光纤中红外被动调Q脉冲激光器中.在吸收抽运功率为1.52 W时,获得平均输出功率为190 mW的脉冲激光,最窄脉冲宽度为607 ns,重复频率为58.51 kHz,对应的单脉冲能量和峰值功率分别为3.25μJ和5.35 W.结果表明,使用铋纳米片作为可饱和吸收体,是实现结构紧凑的小型中红外单晶光纤脉冲激光的有效技术途径.

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.

Mid-infrared SESAM mode-locked Er:CaF_(2)-SrF_(2)bulk laser at 2.73µm

To the best of our knowledge,this is the first time that a mid-infrared Er^(3+):CaF_(2)-SrF_(2) laser has achieved continuous-wave mode-locked operation by a semiconductor saturable absorber mirror.The laser emits a maximum output power of 93 mW at 2.73μm with a repetition rate of approximately 69 MHz and demonstrates a high signal-to-noise ratio of around 71 dB.In addition,a MgF_(2) birefringent plate was utilized to enable wavelength tuning of the Er^(3+):CaF_(2)-SrF_(2) laser,resulting in operation at approximately 2.73μm,2.75μm,2.79μm,and 2.81μm.These results demonstrate that Er^(3+):CaF_(2)-SrF_(2) is a promising alternative for the generation of efficient diode-pumped mode-locked lasers around 2.8μm.

基于钕钆双掺氟化钙晶体的调谐和双波长锁模激光器

Nd,Gd:CaF2是一种无序结构晶体,具有光谱宽、热导率高、透射范围大、声子能量低等优势。利用0.5%Nd,8%Gd:CaF2晶体作为激光增益介质(百分数为原子数分数),实现了LD抽运的调谐激光输出,激光调谐波长范围为1045.7~1074.2 nm;将半导体可饱和吸收镜作为锁模元件,最终实现了双波长锁模激光输出,锁模激光器的中心波长分别位于1065.45 nm和1066.48 nm。锁模激光器的最大平均输出功率约为394 mW,最小脉冲宽度约为8.37 ps。

High repetition rate passively Q-switched laser on Nd:SRA at 1049 nm with MXene Ti3C2Tx

A new disordered crystal Nd:SrAl12O19(Nd:SRA)with an Nd3+doping concentration of 5%was successfully grown using the Czochralski method.A diode-pumped Nd:SRA Q-switched laser operating at 1049 nm was demonstrated for the first time,to the best of our knowledge.Based on an MXene Ti3C2Tx sheet,a high repetition rate of 201 kHz and a Q-switched pulse width of 346 ns were obtained when the absorbed pump power was 2.8 W.The peak power and single pulse energy were 1.87 W and 0.65μJ,respectively.