Abstract: A folded slab waveguide laser having a hybrid waveguide-unstable resonator cavity. Multiple slab waveguides of thickness ‘t’ supporting vertical waveguide modes are physically arranged above one another in a stack and optically arranged in series through one or more cavity folding assemblies with curved mirrors. A gain medium such as a gas is arranged in each slab. Each cavity folding assembly is designed to redirect the radiation beam emitted from one slab waveguide into the next waveguide and also at the same time to provide a focus for the radiation beam so that a selected vertical waveguide mode (or modes) is (or are) coupled efficiently into the next slab.

Abstract: Embodiments of the present disclosure generally relate to methods for preparing carbon materials which can be used in battery electrodes. More specifically, embodiments relate to methods for preparing hard carbon materials used as anode materials in metal-ion batteries, such as a sodium-ion battery. In one or more embodiments, a method includes exposing a liquid refinery hydrocarbon product to a first functionalization agent containing sulfur to produce a first solid functionalized product containing sulfur during a first functionalization process. The method further includes purifying the first solid functionalized product during a purification process and exposing the first solid functionalized product to a second functionalization agent containing oxygen to produce a second solid functionalized product containing sulfur and oxygen during a second functionalization process.