A wavelength-switchable L-band erbium-doped fiber laser (EDFL) assisted by an artificially controlled backscattering (ACB) fiber reflector is here presented. This random reflector was inscribed by femtosecond (fs) laser direct writing on the axial axis of a multimode fiber with 50 μm core and 125 μm cladding with a length of 17 mm. This microstructure was placed inside a surgical syringe to be positioned in the center of a high-precision rotation mount to accurately control its angle of rotation. Only by rotating this mount, three different output spectra were obtained: a single wavelength lasing centered at 1574.75 nm, a dual wavelength lasing centered at 1574.75 nm and 1575.75 nm, and a single wavelength lasing centered at 1575.5 nm. All of them showed an optical signal-to-noise ratio (OSNR) of around 60 dB when pumped at 300 mW.

高脉冲能量和窄脉冲宽度的激光放大器可以应用在诸多领域，例如激光加工、激光医疗美容和激光雷达。种子源激光器与行波放大结构相结合的主振荡功率放大（MOPA）技术，既能保证输出的脉冲激光相关特性（如脉宽和重复频率等）与种子源特性一致，又能实现激光输出能量的放大。因此MOPA技术成为激光放大器工程应用中的主要技术。本课题针对医疗美容对亚纳秒级大能量激光放大器的需求，研制了一台基于亚纳秒微片固体激光器的激光放大器。首先，采用亚纳秒被动调Q微片固体激光器作为种子源。种子源激光器在重复频率为10 Hz，脉冲宽度为487.3 ps时输出能量为190 μJ的1064 nm种子光。然后，利用自制的两个氙灯泵浦Nd: YAG模块作为主放大器对亚纳秒激光脉冲能量进行放大，对放大过程自激振荡产生的能量实现了抑制，有效地提高了放大过程中的能量转换效率。最终，得到了波长1064 nm和532 nm可切换输出，在重复频率为10 Hz时，获得了脉冲宽度496.4 ps，脉冲能量561 mJ@1064 nm，330 mJ@532 nm，能量稳定性2%且光斑均匀的亚纳秒激光输出。