nc-Si／SiNx超晶格薄膜实现Nd：YAG激光器调Q和锁模

Passive Q-switching and Mode Locking of Pulsed Nd:YAG Laser with nc-Si/SiN_x Multilayer

采用射频磁控反应溅射法制备a-Si/SiNx超晶格薄膜材料,热退火后形成纳米Si晶粒。把nc-Si/SiNx薄膜作为饱和吸收体插入Nd:YAG激光器腔内,在腔长较短时,实现1.06μm激光的被动调Q运转,获得最小脉宽23ns的调Q单脉冲输出,当腔长增加到124cm时,获得平均脉宽35ps的锁模脉冲序列。根据实验现象结合薄膜结构,分析了材料调Q与锁模的产生机制,并研究了不同工作条件下的调Q输出性能。

The a-Si/SiNx supedattice was prepared by RF magnetron reaction sputtering technique and thermal annealing, which made Si nanocrystals appear in the a-Si films. In the experiment, the sample was inserted as saturable absorber into the resonator of Nd： YAG laser. The passive Q-switched operation of 1 064 nm laser was achieved when cavity-length was short, and a single pulse waveform of 23 ns-wide was measured. In addition, a single pulse train with average pulse duration of 35 ps was obtained when the cavity-length was set to 124 cm. With the experiment phenomenon and the structure of film, the dynamics of the pulses formation is described; it was mainly ascribed to two-photon saturable absorption and fast relaxation processes of carriers excited in the nano-silicon with quantized states and interface states. The Q-switched output performance in different operating conditions was investigated by the way.