Two back-to-back miter bends with a fused quartz insert instead of a mirror can perform as a beam combiner or beam splitter. When the power split is equal, this component is also called a 3 dB hybrid.
Beam splitting can also be achieved with grid polarizers, consisting of a parallel array of metal wires. In grid polarizers, the component of the incident field parallel to the wires is reflected. Grid polarizers are capable of much wider bandwidths than fused quartz combiner/splitters.
High-power beam combiners/splitters can also be provided. The fused quartz versions are air cooled. Narrowband grid polarizer combiners/splitters use water-cooled tubes instead of wires.