Metallic attenuated total reflection infrared hollow fibers for robust optical transmission systems

Abstract

A durable metallic attenuated total reflection (ATR) hollow fiber (bore size: 1.45 mm, wall thickness: 50 μm) was designed and fabricated based on a nickel capillary tube and hexagonal germanium dioxide (GeO2). The anomalous dispersion of the hexagonal GeO2 layer grown inside a nickel tube achieves low-loss light transmission at two peak-power wavelengths for CO2 laser devices (10.2 and 10.6 μm). An 11–28 W, 10.2 or 10.6 μm CO2 laser power was steadily delivered via a fiber elastically bent from 0° to 90° (radius: 45 cm) for over 40 min (transmission loss: 0.22 to 4.2 dB/m). Theoretically fitting the measured temperatures showed that front-end clipping caused greater thermal loading than the distributed mode absorption. The maximum external temperature of a nickel ATR fiber is much lower than that of a silica glass ATR fiber owing to their different heat dissipation abilities. The HE11 mode purity of the output beam profiles decreased from 90.3% to 44.7% as the bending angle increased from 0° to 90°. Large core sizes and wall roughnesses (scattering loss 0.04 dB/m) contributed to mode mixing and excess losses that were above the value predicted by the classical Marcatili and Schmeltzer equation (0.024–0.037 dB/m).

One-Dimensional Photonic Crystal Inner Coated Hollow Fiber Sensor Based on Bloch Surface Wave With Ultra-High Figure of Merit

“…To avoid the bulky disadvantage caused by the prism, many kinds of optical fiber sensors characterized by miniaturization, low cost and high sensitivity were studied in recent years [18], [19]. Among these fibers with various structures, the hollow fiber (HF) which consists of a supporting tube with metallic and dielectric films coated on its inner surface and a hollow core has also been applied for sensing due to its unique advantages [20], [21]. The hollow core is used for transmitting light while containing the sensed liquid medium, saving the space for an external cavity and avoiding the problem for processing the cladding of the fiber.…”