An optical substrate having a structured light output surface that comprises rows of laterally arranged snaking, wavy or meandering longitudinal prism structures. The prism structures at the light output surface may be viewed as comprising rows of laterally meandering longitudinal prisms and/or sections of curved segments coupled end-to-end to form the overall meandering longitudinal prism structures. The laterally meandering rows of longitudinal prism structures are arranged in parallel laterally (side-by-side), defining parallel peaks and valleys (a facet is defined between each adjacent peak and valley). In one embodiment, the lateral waviness is regular with a constant or variable wavelength and/or wave amplitude (or extent of lateral deformation). The lateral waviness may generally follow a sinusoidal profile, or other curved profile. The structured light output surface may further include varying peak heights along each wavy prism structure and/or pre-defined structural irregularities such as non-facet flat section distributed in the structure surface.