Hybrid-order Poincaré sphere beam fiber laser

In this work, a hybrid-order Poincaré sphere (HyOPS) beam fiber laser was reported and demonstrated, which can yield the vector vortex beam in the cavity directly and realize the polarization evolution at an arbitrary position on the HyOPS. The conversion between the Pancharatnam topological charge and polarization topological charge was realized by the Pancharatnam-Berry phase modulation in the spatial loop of a fiber laser. Then, the HyOPS beam laser was established, achieving continuous wave and mode-locked operations. The mode-locked HyOPS beam laser can be achieved with pulse width, repetition frequency, center wavelength, and 3 dB bandwidth of 128 ps, 13.74 MHz, 1039.84 nm, and 2.3 nm at [-4, 2, Φ, Θ], respectively. [m, n, Φ, Θ] is the mode vector, where m and n represent the topological charges of the vortex beams at the two poles of HyOPS; Φ and Θ represent the coordinates of HyOPS, respectively. This intra-cavity approach offers a compact and integrated solution to generate full-state HyOPS beams, and provides a new strategy for source-level design of complex structured light. The results may be instructive for the generation of the HyOPS beam directly.