2.0μm掺铥超短脉冲光纤激光器研究进展及展望

Progress and Prospect on Ultrafast Tm-Doped Fiber Lasers at 2 μm Wavelength

2.0μm掺铥脉冲光纤激光器在人眼安全雷达、激光医疗、光电对抗以及特殊材料加工等领域具有重要应用,近年来成为新型光纤激光源研究的热点。对国内外2.0μm掺铥超短脉冲光纤激光器的研究进展进行了归纳与总结,内容包括:实现掺铥超短激光脉冲振荡输出的技术手段;新型被动锁模可饱和吸收材料,被动锁模掺铥光纤激光输出的性能及优劣;高功率掺铥超短脉冲光纤放大器的最新研究进展等。技术手段涉及主动锁模、非线性偏振演化锁模、可饱和吸收体锁模和非线性放大环镜锁模。新型可饱和吸收材料主要包括半导体、碳纳米管、石墨烯以及氧化石墨烯等。本课题组最新研究结果表明高功率掺铥超短脉冲光纤放大器的平均输出功率可达80 W,激光脉冲宽度为20ps,激光中心波长为1963nm。对此类超短脉冲光纤激光器的进一步发展及应用给予了展望。

Thulium-doped pulsed fiber lasers have attracted considerable interests as novel laser source, due to their wide applications in eye-safe lidar, laser medical system, optoelectronic countermeasure and special material processing. The research and development on ultrafast thulium-doped fiber laser at 2μm wavelength are classified, which include the technical approach of the ultrafast thuliun doped pulse output, the novel saturable absorbers of passive mode-locking, the characteristics of thulium-doped passively mode-locked fiber laser output, and the development of high power thulium-doped ultrafast pulse amplifier. Up to now, several main mode-locked techniques, such as actively mode-locking, nonlinear polarization evolution, saturable absorber, and nonlinear amplifier loop mirror have been used to achieve ultrashort laser pulses in thulium-doped fiber lasers. The saturable absorber material mainly include semiconductor, carbon nanotubes, graphene and graphene oxide. The most recent work shows that 80 W average power at 1963 nm has been obtained in a three-stage fiber amplifier with pulse width of 20 ps. The prospect of further development and application of such ultrafast laser sources is discussed in the last part of the article.