Rastgarjazi Mohammadmahdi, Vuong Barry, Gu Xijia, Yang Victor X D
Fiber Optic Communication and Sensing Laboratory, Department of Electrical and Computer Engineering, Toronto Metropolitan University, 350 Victoria Street., Toronto, Ontario M5B2K3, Canada.
Biophotonics and Bioengineering Laboratory, Department of Electrical and Computer Engineering, Toronto Metropolitan University, 350 Victoria St., Toronto, Ontario M5B2K3, Canada.
Biomed Opt Express. 2024 Jul 25;15(8):4815-4828. doi: 10.1364/BOE.529062. eCollection 2024 Aug 1.
We demonstrate a high peak power, all-fiber passively Q-switched Tm-doped laser operating at 1940 nm for applications in soft tissue ablation. High peak power and passive Q-switching were achieved via a clad pumped gain fiber and a smaller core Tm-doped fiber saturable absorber respectively. Clad pumping was achieved via two 30 W diodes operating at 793 nm. At 50.7 W of pump power, laser pulses with 140 ns FWHM duration and average power of 14.5 W were obtained at a repetition rate of 328 kHz which corresponded to a pulse energy of ~44 µJ and a peak power of ~316 W. The laser had a narrow 0.14 nm linewidth at the maximum output power. The laser was used to cut chicken breast as well as ovine cortical and subcortical brain tissues and average ablation efficiencies of 29, 40 and 42% were obtained, respectively. Cutting speeds of 10 mm/s for ovine brain tissue and 5 mm/s for chicken breast were achieved. Further resection experiments were performed with the target tissue placed under a thin layer of water. A resected volume with length, width and depth of 5 mm, 2.5 mm, and 2.8 mm were obtained, corresponding to a resection rate of ~0.58 mm/s. To our best knowledge, this is the first report of an all-fiber clad-pumped passively Q-switched Tm-doped fiber laser with a core mismatched saturable absorber being used for tissue ablation experiments.
我们展示了一种高峰值功率、全光纤被动调Q掺铥激光器，其工作波长为1940nm，用于软组织消融应用。分别通过包层泵浦增益光纤和较小芯径的掺铥光纤可饱和吸收体实现了高峰值功率和被动调Q。通过两个工作在793nm的30W二极管实现包层泵浦。在泵浦功率为50.7W时，获得了脉宽为140ns、平均功率为14.5W的激光脉冲，重复频率为328kHz，对应脉冲能量约为44μJ，峰值功率约为316W。该激光器在最大输出功率时线宽为0.14nm，很窄。该激光器用于切割鸡胸肉以及羊的皮质和皮质下脑组织，分别获得了29%、40%和42%的平均消融效率。实现了羊脑组织10mm/s和鸡胸肉5mm/s的切割速度。在目标组织置于薄层水之下的情况下进行了进一步的切除实验。获得了一个长、宽、深分别为5mm、2.5mm和2.8mm的切除体积，对应切除速率约为0.58mm/s。据我们所知，这是首次报道使用具有芯径失配可饱和吸收体的全光纤包层泵浦被动调Q掺铥光纤激光器进行组织消融实验。
