Research on Preparation and Mode Conversion Application of Narrowband Hollow-core Anti-resonant Fiber

Due to the unique characteristics of the hollow core fiber(HCF), more and more researchers pay attention to its application. Because the mode field is mainly limited to the core region of the fiber, which results in low non-linearity, ultra-low group velocity dispersion, low temperature sensitivity, and high material damage threshold. Based on above, there are some attractive nonlinear applications of the HCF, such as transmission of high-power laser beams, sensing, ultra-wide band low-loss transmission, pulse compression and super-continuum generation. Besides, the HCF can be further divided into the transmitting band-gap photonic crystal fiber(PBG-PCF) and the hollow-core anti-resonant fiber(HC-ARF). Compared with the PBG-PCF, the latter has wider light guiding characteristics caused by leaking modes. According to the research in the recent year, the HC-ARF has gradually approached the performance of the PBG-PCF in its transmission loss which shows that it has potential applications of communications, sensing, aerospace, high-power laser transmission and other fields in the future. In addition, the HC-ARF with the special light-guiding properties has also become the important photonic devices in the fields of fiber filters, mode conversion, etc. In this paper, a hollow-core anti-resonance fiber is studied and its light transmission performance in the spectral range of 500 ~ 1500 nm is verified. The optical loss measured at 980 nm wavelength is about 0.32 db/m. It is founded that a 980nm multi-mode laser beam can be converted into a singe-mode one after transmitting through the hollow core fiber we designed.