简化腔结构的大模场面积光纤锁模激光器

Mode-Locked Large-Mode-Area Photonic Crystal Fiber Laser with Simple Cavity Configuration

实验研究了基于国产高增益掺Yb^3＋双包层大模场面积（LMA）光纤的简化腔结构激光器的稳定锁模运转，直接使用塌陷打磨之后的光纤端面作为线型腔中的一端腔镜，利用打磨为O°角之后的光纤端面4％的反射率，在高增益的条件下获得了激光振荡，并进一步利用半导体可饱和吸收镜（SESAM）获得稳定的锁模输出，得到了平均功率分别为144mW和120mw，重复频率均为68MHz（对应单脉冲能量分别为2．1nJ和1．8nJ），脉冲宽度分别为9．9ps和4．8ps的超短脉冲输出。通过增加抽运功率，得到了功率分别为150mW和220mW的稳定多脉冲输出，对应脉冲个数为两个和四个。进而通过激光谐振腔中的光栅对，实现了波长1020～1080nm宽带可调谐的超短脉冲输出。

An Yb-doped double clad large mode area（LMA） fiber laser with a novel simple cavity configuration is demonstrated. This fiber laser system applies one end face of the fiber directly as a cavity mirror, which is fine polished after collapsing. Laser is obtained with the 4% feedback of the end face which has been polished at an angle of 0°, and mode-locking is achieved by using a semiconductor saturable absorber as another cavity mirror. The average output powers are 144 mW and 120 mW with the repeatition frequency of 68 MHz （the corresponding single pulse energies are 2.1 nJ and 1.8 nJ ）, and the pulse widths are 9.9 ps and 4.8 ps,respectively. By increasing the pump power, stable multi-pulse outputs of 150 mW and 220 mW are obtained, which demonstrates the power energy of two and four pulses accordingly. Furthermore, by adding grating pairs inside the cavity, the output wavelength is tunable in the 1020-1080nm range.