Proceedings Article | 19 November 2019
Xiu Zhang, Wenhui Jiang, Zhengxiong Zhang, Panyun Gao, Liang Chen, Peng Wang, Wei Zhang, Yong Zhou, Meisong Liao, Takenobu Suzuki, Yasutake Ohishi, Weiqing Gao
Proc. SPIE. 11195, Quantum and Nonlinear Optics VI
KEYWORDS: Optical fibers, Mid-IR, Refractive index, Photonic crystal fibers, Dispersion, Glasses, Solitons, Raman scattering, Supercontinuum generation, Selenium
Characteristics of vector beams in mid-infrared waveband are analyzed numerically in an As<sub>2</sub>Se<sub>3</sub> photonic crystal fiber (PCF) with small central hollow core (SCHH), including the mode fields, confinement loss, effective refractive index and chromatic dispersion. In the PCFs with the SCHH diameter d<sub>0</sub> of 0-1.5 μm, the confinement losses of the four vector beams (HE<sub>11</sub>, TM<sub>01</sub>, TE<sub>01</sub>, and HE<sub>21</sub>) are smaller than 1.0 dB/m for the wavelengths up to ~5 μm. For the SCHH diameter d<sub>0</sub> of 0.5-1.5 μm, the field enhancement of the HE<sub>11 </sub>mode occurs in the SCHHs in the central area for the wavelengths ≤ 5 μm. This happens because the evanescent light penetrates into the SCHH. With d<sub>0</sub> increasing, the effective refractive index separations (δ<sub>neff</sub>) between the HE<sub>11 </sub>mode and high-order modes (TM<sub>01</sub>, TE<sub>01</sub>, and HE<sub>21</sub>) decreases, while the δ<sub>neff </sub>among the high-order modes increases. At the wavelength of 5 μm, the δ<sub>neff</sub> of HE<sub>11</sub>-TE<sub>01</sub>, TE<sub>01</sub>- HE<sub>21</sub>, and HE<sub>21</sub>-TM<sub>01</sub> is 0.03098, 0.03960, and 0.06867, respectively, when d<sub>0</sub> is 1.5 μm. The second ZDWs of TE<sub>01</sub>, HE<sub>21</sub> and TM<sub>01 </sub>mode are blueshifted with the increase of d<sub>0</sub>, but they are longer than 5 μm. The negative dispersion regions of the high-order modes (TE<sub>01</sub>, HE<sub>21</sub>, and TM<sub>01</sub>) are much wider than the HE<sub>11</sub> modes. With the increase of d<sub>0</sub>, the HE<sub>11</sub> mode dispersion curves have no obvious change, while the high-order modes (TE<sub>01</sub>, HE<sub>21</sub>, and TM<sub>01</sub>) dispersion curves become steep at the longer wavelength, the TM<sub>01</sub> mode changes most obviously, and the depression appears. To demonstrate the application of the PCF, super-continuum generation pumped by the four vector modes are simulated and analyzed. Our simulated results will be useful for the optical applications in mid-infrared waveband, such as the generation of cylindrical vector mode and orbital angular momentum (OAM) and the particle manipulation by optical fields.
