碲化铋倏逝场锁模器件的超快光纤激光器

Ultrafast fiber laser based on bismuth telluride evanescent field mode-locked device

为使光纤激光器在被动谐波锁模状态下实现锁模脉冲高重复频率输出,本文通过激光沉积法制备了一种基于非线性拓扑绝缘体材料碲化铋与侧面抛磨光纤相结合的可饱和吸收体锁模器件,该器件调制深度、非饱和损耗、饱和强度分别为23.96%、37.77%、31.5 MW/cm^(2)。将其应用在掺铒光纤激光器中,通过对整个腔内色散参数的调整,以及利用材料自身良好的非线性可饱和吸收能力,成功实现了锁模自启动,其中心波长为1555.67 nm,脉冲宽度为487 fs,重复频率为47.87 MHz,信噪比为58 dB。当泵浦功率超过150 mW时出现锁模脉冲的谐波分裂,持续对泵浦功率进行微调,增加直至最高功率250 mW时,出现了11阶谐波锁模脉冲,重复频率最高达到528 MHz,此时的信噪比为41.5 dB。本文结果证明利用侧面抛磨光纤结构的倏逝场,能够辅助材料提升一定的激光抗损伤能力,便于其在基本锁模状态下进一步实现被动谐波锁模,满足锁模脉冲高重频的产生及探究,对材料在高重频超快光纤激光器中的应用具有重要意义。

In order to realize the passively harmonic mode-locking with high repetition rate in the fiber laser.A saturable absorber(SA)based on two dimensional(2D)topological insulators material of Bismuth telluride(Bi_(2)Te_(3)),combining with a side-polished fiber,was fabricated by laser deposition technology in this study.This device has a modulation depth of 23.96%,nonsaturable loss of 37.77%and saturable intensity of 31.5 MW/cm^(2).According to the adjustment of dispersion in the whole cavity and the excellent nonlinear saturable absorb character in topological insulator materials,a self-starting mode-locking is realized successfully when this SA device is applied in the Er-doped fiber laser,with a central wavelength of 1555.67 nm,pulse duration of 487 fs,repetition rate of 47.87 MHz and signal-to-noise ratio of 58 dB.A harmonic mode-locking is achieved when the pump power is over 150 mW.When we adjust and increase slightly the pump power till 250 mW,the harmonic mode-locking of 11 orders is achieved with the repetition rate of 528 MHz and the signal-to-noise ratio of 41.5 dB.These results demonstrate that with the evanescent field produced by the side-polished fiber,the damage threshold of materials can be improved and the passively harmonic mode-locking with high repetition rate is realized,which has a great significance for the materials in the application of ultrafast fiber laser with high repetition rate.