Twist-direction-dependent orbital angular momentum generator based on inflation-assisted helical photonic crystal fiber.

A novel twist-direction-dependent high-order orbital angular momentum (OAM) generator based on an inflated helical photonic crystal fiber (IHPCF) was demonstrated by use of an inflation-assisted hydrogen-oxygen flame heating technique. Compared with the helical photonic crystal fiber, the IHPCF exhibits a perfect transmission dip without distinct splits, thus generating high-quality OAM±6 modes. The helical phase of the generated OAM modes is dependent on the twist direction of the IHPCF and independent of the polarization state of the input light. In addition, the polarization state of the generated OAM modes is the same as that of the input light.