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实验搭建了全保偏结构的掺镱皮秒脉冲光纤激光器,采用级联放大结构及双包层保偏光子晶体光纤将种子脉冲能量提升至最高10μJ,重复频率0.05~20.00MHz连续可调。主放大器中的纤芯/包层直径为14/135μm保偏光子晶体光纤,不仅可以实现与少模双包层光纤的直接熔接,确保光纤放大器的全光纤结构,而且有效降低了皮秒脉冲放大过程中的非线性效应,较好的保持了输出脉冲的时频域特性。采用1 064nm皮秒脉冲光源结合扫描电镜,照射浸泡在蒸馏水中的二氧化钛(TiO_2)粉末压片,制备出TiO_2纳米颗粒,利用透射式电子显微镜(TEM)对TiO_2纳米颗粒尺寸进行了测量。当采用在100kHz的重复频率,每脉冲能量为5μJ,脉冲串内3脉冲工作方式,制备所得的粒子直径分布在50~350nm之间。当脉冲串内的脉冲数从3个增加至5个后,制备出纳米颗粒的平均直径从234nm缩小为162nm,且产率从3.9mg/h提升至5.5mg/h。
The experimental results show that the pulse energy of the seed pulse can be increased to 10μJ and the repetition frequency of 0.05 ~ 20.00MHz can be continuously adjusted by adopting the cascaded amplifying structure and the double-cladding polarization-maintaining photonic crystal fiber. The main amplifier core / cladding diameter of 14 / 135μm polarization-maintaining photonic crystal fiber, not only can be achieved with a small mold double clad fiber direct fusion, to ensure that the optical fiber amplifier all-fiber structure, and effectively reduce the picosecond pulse amplification The non-linear effect in the process keeps the time-frequency characteristics of the output pulse well. TiO 2 nanoparticles were prepared by irradiating TiO 2 powder in distilled water with 1 064 nm picosecond pulse light source and scanning electron microscope (SEM). The size of TiO 2 nanoparticles was measured by transmission electron microscopy (TEM). When used at a repetition rate of 100 kHz, the energy per pulse is 5 μJ and the pulse train operates in 3-pulse mode. The resulting particles are distributed between 50 and 350 nm in diameter. When the number of pulses in the pulse train increased from 3 to 5, the average diameter of the prepared nanoparticles was reduced from 234 nm to 162 nm, and the yield was raised from 3.9 mg / h to 5.5 mg / h.