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报道了一种掺Yb偏振型大模场面积光子晶体光纤(LMA-PCF)飞秒激光器。作为增益介质的光子晶体光纤的单模场面积比传统光纤高一个数量级,有效地降低了非线性系数,使激光器获得高能量输出。激光器基于线形腔结构,利用半导体可饱和吸收镜实现自启动锁模。光纤激光器利用光栅对进行腔内色散补偿,使其运转在呼吸脉冲锁模状态,即在谐振腔的零色散点附近实现锁模。当腔内净色散呈反常色散时,激光器获得了平均功率为400mW,重复频率为47MHz(对应于8.5nJ的单脉冲能量),脉冲宽度为500fs的稳定的锁模脉冲输出,经腔外色散补偿,脉冲压缩至98fs。当腔内净色散呈正常色散时,激光器输出的单脉冲能量为10.6nJ,脉冲宽度为1.76ps,经腔外色散补偿,脉冲压缩至160fs。
A Yb polarization-mode large mode area photonic crystal fiber (LMA-PCF) femtosecond laser is reported. As a gain medium, the single mode field of photonic crystal fiber is an order of magnitude higher than that of conventional fiber, which effectively reduces the nonlinear coefficient and makes the laser obtain high energy output. Laser based on linear cavity structure, the use of semiconductor saturable absorption mirror to achieve self-starting mode-locking. The fiber laser compensates the dispersion in the cavity by using the grating pair, and operates in the mode of the pulse-pulse clamping, that is, the mode-locking is implemented near the zero-dispersion point of the resonator. When the intracavity net dispersion was anomalous dispersion, the laser obtained an average power of 400mW, a repetition frequency of 47MHz (corresponding to a single pulse energy of 8.5nJ), a pulse width of 500fs stable mode-locked pulse output, extra-cavity dispersion compensation , Pulse compression to 98fs. When the net dispersion in the cavity is normal dispersion, the laser output single-pulse energy of 10.6nJ, pulse width of 1.76ps, compensated by extra-cavity dispersion, pulse compression to 160fs.