基于WS_2可饱和吸收体的调Q锁模Tm,Ho:LLF激光器  

Passively Q-switched mode-locked Tm,Ho:LLF laser with a WS_2 saturable absorber

作　　者：令维军[1] 夏涛[1] 董忠[1] 刘勍[1] 路飞平[1] 王勇刚[2] 

机构地区：[1]天水师范学院激光技术研究所,天水741001 [2]陕西师范大学物理学与信息技术学院,西安710062

出　　处：《物理学报》2017年第11期130-135,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61465012;61564008;61461046;61665010)资助的课题~~

摘　　要：采用聚乙烯醇塑料膜为基质的WS_2作为可饱和吸收体,在Tm,Ho:LiLuF_4全固态激光器中实现了被动调Q锁模运转.以掺钛蓝宝石激光器作为抽运源,当最大吸收抽运功率为2.6 W时,激光输出功率为156 mW,典型的调Q脉冲包络重复频率为25 kHz,脉宽约为300μs.当吸收功率大于1.39 W时,进入稳定调Q锁模运转,对应锁模脉冲序列的重复频率为131.6 MHz,调整深度接近100%.结果表明:WS_2可以作为2μm波段全固态激光器锁模的吸收体材料.Using few-layer tungsten disulfide （WS2） doped polyvinyl alcohol as a saturable absorber for the initiation of the pulse generation, we experimentally demonstrate stable passively Q-switched mode-locked operations of Tm, Ho：LiLuF4 laser at 1895 nm for the first time. The laser is designed with an X-type four-mirror cavity and pumped by a Ti：sapphire laser operated at 785 nm, and its continuous operation is initiated when the absorbed pump power is 143 mW. When the absorbed pump power reaches 2.645 W, we obtain a maximum output power of 985 mW and a crystal slope efficiency of 39.8% by linear fitting. When the saturable absorber WS~ is inserted in the cavity, the threshold of the absorbed pump power is increased to 234 roW. With the increase of the pump power, Q-switch pulse sequence is first observed. When the absorbed pump power reaches 1.39 W, the stable operation of the Q-switched mode locked pulse is realized. A maximum average output power of 156 mW is achieved at an absorbed pump power of 2.6 W, which corresponds to a 25 kHz Q-switched repetition rate and a 300 ~s-long pulse envelope. In this case, the modulation depth in Q-switching envelopes is close to 100%. After the passively Q-switched mode-locked is obtained stably, the mode-locked pulses inside the Q-switched pulse envelope have a repetition rate of 131.6 MHz, corresponding to a mode locked pulse energy of 1.19 nJ and a cavity length of 1.14 m. According to the definition of the rise time and considering the symmetric shape of the mode locked pulse, we can assume that the duration of the pulse is approximately 1.25 times more than the rise time of the pulse. Then the width of the mode locked pulse is estimated to be about 878 ps. These experimental results show that WS2 is a promising broadband saturable absorption material for generating a 2 ~m-wavelength mid-infrared solid-state laser pulse. By increasing the pump power and reducing the loss of WS2 material, it is possible to realize a continuous mode locking operation which has a narrower

关 键 词：TM Ho:LLF激光器 调Q锁模 可饱和吸收体 WS2 

分 类 号：TN248[电子电信—物理电子学]