Peng Kaung-Jay, Lin Yung-Hsiang, Wu Chung-Lun, Lin Sheng-Fong, Yang Chun-Yu, Lin Shih-Meng, Tsai Din-Ping, Lin Gong-Ru
Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, National Taiwan University (NTU), No.1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan, Republic of China.
Department of Physics, National Taiwan University (NTU), No.1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan, Republic of China.
Sci Rep. 2015 Sep 2;5:13689. doi: 10.1038/srep13689.
The in-situ dissolution-and-reduction CVD synthesized few-layer graphene on ultra-thin nickel catalyst film is demonstrated at temperature as low as 550 °C, which can be employed to form transmission-type or reflection-type saturable absorber (SA) for mode-locking the erbium-doped fiber lasers (EDFLs). With transmission-type graphene SA, the EDFL shortens its pulsewidth from 483 to 441 fs and broadens its spectral linewidth from 4.2 to 6.1 nm with enlarging the pumping current from 200 to 900 mA. In contrast, the reflection-type SA only compresses the pulsewidth from 875 to 796 fs with corresponding spectral linewidth broadened from 2.2 to 3.3 nm. The reflection-type graphene mode-locker increases twice of its equivalent layer number to cause more insertion loss than the transmission-type one. Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design.
在低至550°C的温度下，展示了原位溶解还原化学气相沉积法在超薄镍催化剂薄膜上合成的少层石墨烯，其可用于形成透射型或反射型可饱和吸收体（SA），以锁模掺铒光纤激光器（EDFL）。使用透射型石墨烯SA，随着泵浦电流从200 mA增大到900 mA，EDFL的脉冲宽度从483 fs缩短至441 fs，光谱线宽从4.2 nm拓宽至6.1 nm。相比之下，反射型SA仅将脉冲宽度从875 fs压缩至796 fs，相应的光谱线宽从2.2 nm拓宽至3.3 nm。反射型石墨烯锁模器的等效层数增加了一倍，导致其插入损耗比透射型的更大。然而，基于反射型的可饱和吸收体系统比透射型系统更容易产生稳定的类孤子脉冲，因为在反射镜设计下，当光两次穿过石墨烯时，非线性诱导的自振幅调制深度会同时增大。
