Generation of Dispersive Waves in Double-Ring Core Fiber for High-Order OAM Modes

We propose and design a dual-ring core fiber to generate multiple dispersive waves (DWs) for high-order orbital angular momentum modes. By calculating phase-matching conditions, the quantity and location of DWs can be predicted. When a pulse is pumped in the normal dispersion region, the coherent output spectrum of the OAM20,1 mode spans from 0.6 to1.7~μm, exhibiting five DWs located at 630, 740, 890, 1300, and 1510 nm. In addition to optimized fiber parameters to facilitate DWs generation for other OAM modes, the output spectra of OAM18,1 and OAM19,1 modes in the fiber with same structure parameters also exhibit the generation of multiple DWs. The multiple DWs generation method for high-order OAM modes could be applied in fields such as optical coherence tomography, metrology, and spectroscopy.