报道了一种基于锁模掺铒光纤激光器和GaSe晶体的光纤型宽带高效差频产生(DFG)光梳。 该DFG 光梳采用全保偏光纤设计以获得高线偏振度的基频脉冲,采用非线性脉冲光纤放大技术以获取宽带窄脉宽高峰值功率 的双色基频脉冲,从而确保了DFG光梳的宽带和高转换效率特性以及DFG过程的稳定性。该DFG光梳在中心波长8.15 μm处 带宽达1.7 μm, 仅受GaSe晶体相位匹配接受带宽的限制,对应的DFG转换效率达1%, 远高于常规光纤型DFG光梳约0.4%的转换效率。

A broadband difference frequency generation (DFG) comb with high conversion efficiency based on a mode-locked erbium-doped fiber laser and GaSe crystal is presented. The DFG comb adopts all-polarization-maintaining fiber structure to obtain fundamental frequency pulses with high linear polarizations degrees, and the nonlinear pulse fiber amplification technique is utilized to achieve wide bandwidths, short durations and high peak powers, for the two-color fundamental pulses. This offers the DFG comb the properties of wide bandwidth and high conversion efficiency, and the stability of the DFG process. The experimental results show that the achievable bandwidth of the DFG comb near 8.15 μm reaches 1.7 μm, only limited by the phase-matching acceptance bandwidth of the crystal, and the corresponding DFG conversion efficiency is as high as 1%, much higher than that for the fiber-type DFG comb reported so far, which is about 0.4%.