School of Physics and Astronomy, Faculty of Science, Monash University, Melbourne, Victoria, 3800, Australia.
Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig Maximilian University of Munich, Munich, 80539, Germany.
Nat Commun. 2022 Jul 19;13(1):4183. doi: 10.1038/s41467-022-31902-3.
Dispersion engineering is essential to the performance of most modern optical systems including fiber-optic devices. Even though the chromatic dispersion of a meter-scale single-mode fiber used for endoscopic applications is negligible, optical lenses located on the fiber end face for optical focusing and imaging suffer from strong chromatic aberration. Here we present the design and nanoprinting of a 3D achromatic diffractive metalens on the end face of a single-mode fiber, capable of performing achromatic and polarization-insensitive focusing across the entire near-infrared telecommunication wavelength band ranging from 1.25 to 1.65 µm. This represents the whole single-mode domain of commercially used fibers. The unlocked height degree of freedom in a 3D nanopillar meta-atom largely increases the upper bound of the time-bandwidth product of an achromatic metalens up to 21.34, leading to a wide group delay modulation range spanning from -8 to 14 fs. Furthermore, we demonstrate the use of our compact and flexible achromatic metafiber for fiber-optic confocal imaging, capable of creating in-focus sharp images under broadband light illumination. These results may unleash the full potential of fiber meta-optics for widespread applications including hyperspectral endoscopic imaging, femtosecond laser-assisted treatment, deep tissue imaging, wavelength-multiplexing fiber-optic communications, fiber sensing, and fiber lasers.
色散工程对于大多数现代光学系统的性能至关重要，包括光纤器件。尽管用于内窥镜应用的米级单模光纤的色度色散可以忽略不计，但位于光纤端面用于光学聚焦和成像的光学透镜会受到强烈的色差影响。在这里，我们在单模光纤端面上设计并纳米压印了一个 3D 消色差衍射金属透镜，能够在整个近红外电信波长范围内（1.25 到 1.65 μm）实现消色差和偏振不敏感的聚焦。这代表了商用光纤的整个单模域。3D 纳米柱元金属的未锁定高度自由度极大地提高了消色差金属透镜的时间带宽积上限，达到 21.34，从而实现了从 -8 到 14 fs 的宽群延迟调制范围。此外，我们展示了我们的紧凑灵活的消色差金属光纤在光纤共焦成像中的应用，它能够在宽带光照明下创建清晰的焦点图像。这些结果可能会释放光纤亚光学的全部潜力，广泛应用于超光谱内窥镜成像、飞秒激光辅助治疗、深层组织成像、波分复用光纤通信、光纤传感和光纤激光器等领域。
