Formation of laser-induced periodic structures on the end surface of optical fibers

The formation of two-dimensional subwavelength (∼ 660 nm) thermochemical laser-induced surface periodic structures (TLISPS) with different morphologies (hexagonal, square, or mixed type) depending on the exposure parameters (pulse energy and scanning speed) on Ti films with a thickness of 30, 50, and 100 nm has been studied. Diffraction optical elements (2D gratings) were created on the end surface of optical fibers based on the data of highly ordered TLISPS structures, providing diffraction efficiency of up to 8%. The possibility of using fiber-optic diffraction elements to remove radiation from the fiber at certain angles significantly exceeding the initial angle of divergence of radiation from the fiber is demonstrated.