基于单壁碳纳米管可饱和吸收体的被动锁模光纤激光器研究

基于单壁碳纳米管(SWCNTs)作为光学可饱和吸收体(SA)的恢复时间快(<1ps)、饱和光强低、锁模自启动、工作光谱范围宽且制备方法简单、成本低、化学稳定性好、易与光纤兼容等优点,利用SWCNTs-SA实现了稳定脉冲序列输出的实验结果。利用聚甲基丙烯酸甲酯(PMMA)易成膜且机械性能良好的特点,将SWCNTs与PMMA一起分散在二氯化苯(DCB)溶液中,运用光学诱导作用将SWCNTs吸附在单模光纤(SMF)端面,并加热固化成膜。在光纤激光器环形腔结构中引入SWCNT/PMMA薄膜作为SA,获得了具有稳定的重复频率为8.366MHz的基频锁模脉冲序列,其中心波长在1 562nm,脉冲宽度为1.2ps。

A passive mode-locking pulse fiber laser based on single-walled carbon nanotube saturable absorber

As an optical saturable absorber(SA),single-walled carbon nanotubes(SWCNTs) film has many advantages,including ultrafast recovery time,high nonlinearity,broadband operation,and simplicity of fabrication.Together with its low cost,compatibility with fiber,device flexibility etc.,it has attracted much attention in ultrafast laser field.This paper demonstrates the stable passive mode-locking pulse sequence outputs from the fiber laser using SWCNTs as absorber.Since the polymethylmethacrylate(PMMA) is easy to form film and has good mechanical properties,it can be used as a matrix of SWCNTs.Mixing PMMA with single-walled carbon nanotube powder and dispersing them in the 2-dichlorobenzene solution,we made SWCNTs film on the end face of a single-mode optical fiber by means of optical induction.The SWCNTs/PMMA film is introduced in a ring cavity fiber laser as an optical saturable absorber for passive mode-locking,and a stable pulse sequence is obtained experimentally.The output pulses have the repeated frequency of 8.366 MHz,which is the fundamental frequency of the cavity.The central wavelength is 1 562 nm,and the mode-locking pulse trace is 1.2 ps.