Silica hollow core microstructured fibers for beam delivery in industrial and medical applications

Abstract

The focus of this review is recent work to develop microstructured hollow core fibers for two applications where the flexible delivery of a single mode beam is desired. Also, a brief review of other fiber based solutions is included. High power, short-pulsed lasers are widely used for micro-machining, providing high precision and high quality. However, the lack of truly flexible beam delivery systems limits their application to the processing of relatively small planar components. To address this, hollow-core optical fibers for the 1 µm and green wavelength ranges have been developed. The hollow core overcomes the power delivery limitations of conventional silica fibers arising from non-linear effects and material damage in the solid core. The fibers have been characterized in terms of power handling capability, damage threshold, bend loss and dispersion, and practically demonstrated delivery of high peak power pulses from the nanosecond to the femtosecond regime. Such fibers are ideal candidates for industrial laser machining applications. In laser surgical applications, meanwhile, an Er:YAG laser (2.94 µm) is frequently the laser of choice because the water contained in tissue strongly absorbs this wavelength. If this laser beam is precisely delivered damage to surrounding tissue can be minimized. A common delivery method of surgical lasers, for use in the operating theater, is articulated arms that are bulky, cumbersome and unsuitable for endoscopic procedures. To address this need for flexible mid-IR delivery silica based hollow core fibers have been developed. By minimizing the overlap of the light with glass it is possible to overcome the material absorption limits of silica and achieve low attenuation. Additionally, it is possible to deliver pulse energies suitable for the ablation of both hard and soft tissue even with very small bend radii. The flexibility and small physical size of systems based on these fibers will enable new minimally invasive surgical procedures.

Numerical Modeling of Guided Mode for Negative Curvature Hollow-core Fibers

“…(5)(6)(7) A guiding light in a large hollow air-filled core endows NCHCFs with the favorable properties of high power transmission, ultralow dispersion, a large bandwidth, and a simple structure. (8)(9)(10)(11) In 2020, (12) we used a combination of an NCHCF and a gold-plated graded-index fiber to fabricate a hollow-core photonic crystal fiber sensor and we analyzed the sensing properties of the NCHCF sensor by measurement. We also modeled a surface-plasmon photonic crystal fiber (PCF)-based sensor in a hollow-core photonic crystal fiber.…”

Suspended-Core Microstructured Polymer Optical Fibers and Potential Applications in Sensing

“…MOFs have attracted increased interest because of their wide range of unique properties such as ultra-wide single mode operation, tailorable dispersion, high or low nonlinearity, and low-loss guidance in selected spectral regions. Because of these features, MOFs have been widely considered for applications in telecoms, power delivery systems, industrial lasers, environmental monitoring, and medicine/healthcare [1,2,3,4,5].…”

Hundred-meter-scale, kilowatt peak-power, near-diffraction-limited, mid-infrared pulse delivery via the low-loss hollow-core fiber

“…For instance, kilowatt-power, single-mode near-infrared laser beams have now been successfully transmitted over kilometer distances, making them suitable for future industrial manufacturing in giga-factories and subsurface rock drilling, amongst other applications [1]. In the MIR spectral region, there is also a growing drive for such laser delivery systems, for example, in the processing of organic materials [2][3][4], spectroscopy [5], biomedical diagnostics [6], and surgical treatment [7,8]. In laser surgery, for example, optical fibers enhance system flexibility and allow the placement of the laser source far from the operating theater, freeing up space for surgeons and enabling a safer and less cluttered operating environment.…”