Cho Won Bae, Choi Sun Young, Zhu Chunhui, Kim Mi Hye, Kim Jun Wan, Kim Jin Sun, Park Hyung Ju, Shin Dong Ho, Jung Moon Youn, Wang Fengqiu, Rotermund Fabian
Opt Express. 2016 Sep 5;24(18):20774-80. doi: 10.1364/OE.24.020774.
Graphene has proved to be an excellent broadband saturable absorber for mode-locked operation of ultrafast lasers. However, for the mid-infrared (mid-IR) range where broadly tunable sources are in great needs, graphene-based broadly tunable ultrafast mid-IR lasers have not been demonstrated so far. Here, we report on passive mode-locking of a mid-IR Cr:ZnS laser by utilizing a transmission-type monolayer graphene saturable absorber and broad spectral tunability between 2120 nm and 2408 nm, which is the broadest tuning bandwidth ever reported for graphene mode-locked mid-IR solid-state lasers. The recovery time of the saturable absorber is measured to be ~2.4 ps by pump-probe technique at a wavelength of 2350 nm. Stably mode-locked Cr:ZnS laser delivers Fourier transform-limited 220-fs pulses with a pulse energy of up to 7.8 nJ.
石墨烯已被证明是用于超快激光锁模操作的出色宽带饱和吸收体。然而，在迫切需要宽可调谐光源的中红外（mid-IR）范围内，基于石墨烯的宽可调谐超快中红外激光器目前尚未得到证实。在此，我们报告了利用透射型单层石墨烯饱和吸收体实现中红外Cr:ZnS激光器的被动锁模，并在2120纳米至2408纳米之间实现了宽光谱可调谐性，这是迄今报道的基于石墨烯锁模的中红外固态激光器中最宽的调谐带宽。通过泵浦-探测技术在2350纳米波长下测得饱和吸收体的恢复时间约为2.4皮秒。稳定锁模的Cr:ZnS激光器产生傅里叶变换极限的220飞秒脉冲，脉冲能量高达7.8纳焦。
