For analytical purposes a portion can be separated from the incident beam or a selected wavelength can be extracted from or coupled into the optical path. The variety goes from simple plates to sophisticated beamsplitter assemblies. Such components are typically customized and can. Custom designs combining circulators, polarizing splitters and non-polarizing splitters in the same package are routinely manufactured. We offer 2-wavelength fiber WDMs for UV/visible, visible, visible/NIR, or IR wavelengths, 3-wavelength fiber WDMs, 4-wavelength fiber WDMs, and. Thorlabs' Fused Fiber Wavelength Division Multiplexers (WDMs), also known as wavelength combiners/splitters, allow two single-mode signals to be combined into a single output fiber.