基于氧化石墨烯与半导体可饱和吸收镜的锁模飞秒掺铒光纤激光器

Mode-Locked Femtosecond Erbium-Doped Fiber Laser Based on Graphene Oxide versus Semiconductor Saturable Absorber Mirror

分别将氧化石墨烯可饱和吸收镜(GOSAM)与半导体可饱和吸收镜(SESAM)作为可饱和吸收体,在同一掺铒光纤激光器中均实现了全光纤结构、稳定的锁模飞秒脉冲输出。实验用抽运源为中心波长974 nm的半导体激光器,抽运1.4 m长的吸收率为7 d B/m的掺铒光纤,谐振腔总腔长约为12 m。以GOSAM作为可饱和吸收体,当抽运功率为29 m W时,激光器产生稳定的锁模脉冲输出,脉冲宽度最窄为703 fs,光谱中心波长为1557.67 nm,3 d B带宽为3.91 nm。使用调制深度为18%的SESAM作为可饱和吸收体,当抽运功率为32 m W时也可得到锁模脉冲,脉冲宽度为542 fs,光谱中心波长为1561.5 nm,3 d B带宽为5.41 nm。实验表明,新型激光锁模器件氧化石墨烯的可饱和吸收效应可与SESAM媲美,且兼具价格低廉、制备简单的优势,在实现超短脉冲运转方面具有广阔的实际应用前景。

The all-fiber passively mode-locked erbium-doped femtosecond fiber lasers based on semiconductor saturable absorber mirror （SESAM） and graphene oxide saturable absorber mirror （GOSAM） in the same cavity are demonstrated. The fiber ring laser is constituted with 1.4 m Er^3＋-doped fiber as gain medium, which is pumped by 974 nm diode laser, and with the total cavity length of 12 m. Stable mode-locked laser pulse train occurrs at 29 mW incident pump power by employing GOSAM as the saturable absorber. The pulse width is measured to be 703 fs, and the center wavelength is 1557.67 nm, and 3 dB spectral bandwidth is corresponding to 3.91 nm. However, inserting SESAM with a modulation depth of 18% in the configuration mentioned above, we can obtain ultrashort pulse at 32 mW pump power, and the pulse width decreases to 542 fs. The laser center wavelength and the 3 dB spectral bandwidth axe 1561.5 nm and 5.41 nm, respectively. Experimental results show that the novel mode-locking device--graphene oxide has the similiar distinguished saturable absorber ability. With its advantages of low price, simple preparation, it seems to be a good candidate for saturable absorbers in achieving ultrashort pulse operation.