Significance: The highest absorption peaks of the main components of bone are in the mid-infrared region, making Er:YAG and CO2 lasers the most efficient lasers for cutting bone. Yet, studies of deep bone ablation in minimally invasive settings are very limited, as finding suitable materials for coupling high-power laser light with low attenuation beyond 2 μm is not trivial. Aim: The first aim of this study was to compare the performance of different optical fibers in terms of transmitting Er:YAG laser light with a 2.94-μm wavelength at high pulse energy close to 1 J. The second aim was to achieve deep bone ablation using the best-performing fiber, as determined by our experiments. Approach: In our study, various optical fibers with low attenuation (λ = 2.94 μm) were used to couple the Er:YAG laser. The fibers were made of germanium oxide, sapphire, zirconium fluoride, and hollow-core silica, respectively. We compared the fibers in terms of transmission efficiency, resistance to high Er:YAG laser energy, and bending flexibility. The best-performing fiber was used to achieve deep bone ablation in a minimally invasive setting. To do this, we adapted the optimal settings for free-space deep bone ablation with an Er:YAG laser found in a previous study. Results: Three of the fibers endured energy per pulse as high as 820 mJ at a repetition rate of 10 Hz. The best-performing fiber, made of germanium oxide, provided higher transmission efficiency and greater bending flexibility than the other fibers. With an output energy of 370 mJ per pulse at 10 Hz repetition rate, we reached a cutting depth of 6.82 ± 0.99 mm in sheep bone. Histology image analysis was performed on the bone tissue adjacent to the laser ablation crater; the images did not show any structural damage. Conclusions: The findings suggest that our prototype could be used in future generations of endoscopic devices for minimally invasive laserosteotomy.

中文翻译：

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用于内窥镜高功率 Er:YAG 激光截骨术的光纤

意义：骨骼主要成分的最高吸收峰在中红外区域，使得 Er:YAG 和 CO2 激光器成为切割骨骼最有效的激光器。然而，在微创环境中进行深部骨消融的研究非常有限，因为寻找合适的材料来耦合低衰减超过 2 μm 的高功率激光并非易事。目的：本研究的第一个目的是比较不同光纤在接近 1 J 的高脉冲能量下传输波长为 2.94 μm 的 Er:YAG 激光的性能。第二个目的是实现深层骨消融根据我们的实验确定，使用性能最佳的光纤。方法：在我们的研究中，使用各种低衰减（λ = 2.94 μm）光纤来耦合 Er:YAG 激光器。纤维由氧化锗制成，分别是蓝宝石、氟化锆和空心二氧化硅。我们在传输效率、抗高 Er:YAG 激光能量和弯曲柔韧性方面比较了光纤。性能最佳的纤维用于在微创环境中实现深层骨消融。为此，我们使用先前研究中发现的 Er:YAG 激光调整了自由空间深部骨消融的最佳设置。结果：三根光纤在 10 Hz 的重复频率下每脉冲承受高达 820 mJ 的能量。性能最好的光纤由氧化锗制成，比其他光纤提供更高的传输效率和更大的弯曲灵活性。在 10 Hz 重复频率下，每个脉冲的输出能量为 370 mJ，我们在羊骨中达到了 6.82 ± 0.99 mm 的切割深度。对激光烧蚀坑附近的骨组织进行组织学图像分析；图像没有显示任何结构损坏。结论：研究结果表明，我们的原型可用于未来几代用于微创激光截骨术的内窥镜设备。