基于单壁碳纳米管的波长可切换被动锁模光纤激光器

Wavelength Switchable Passive Mode-Locking Fiber Laser Based on Single-Wall Carbon Nanotube

报道了一种基于单壁碳纳米管可饱和吸收体、工作波长可切换的被动锁模光纤激光器。利用可饱和吸收体薄膜厚度调节腔内损耗,不仅实现了基频被动锁模脉冲序列的稳定输出,还有效控制了掺铒光纤激光器的增益谱线。实验表明,当腔内可饱和吸收体薄膜较薄或者较厚时,激光器可以分别产生中心波长为1545nm和1562nm的脉冲;当腔内可饱和吸收体薄膜厚度介于较薄和较厚之间的适当值时,仔细调整偏振控制器,可以实现激光器在这两个中心波长之间相互切换的稳定锁模运转,在切换的过程中还可观察到这两个中心波长同时出现的锁模现象。

A passively mode-locked fiber laser, whose operating wavelength can be switched based on the single-wall carbon nanotube saturable absorber （SWCNT-SA）, is demonstrated. By adjusting the thickness of saturable absorber film to change the intracavity loss, not only stable mode-locked output is obtained, but also the gain profile of the erbium-doped fiber laser is effectively controlled. The experimental results show that the lasers can generate modelocked pulses with the central wavelength of 1545 nm and 1562 rim, in the thinner and thicker SWCNT-SA, respectively. Additionally if the thickness of SWCNT-SA is appropriately controlled between the thinner and thicker ones, the laser can generate pulses both with central wavelength of 1545 nm and 1562 nm, and the operating wavelength can be switched from one to the other by carefully adjusting the polarization controller. In the process of wavelength switching, the phenomenon of mode-locking is also observed when the two central operating wavelengths simultaneously appear.