Fiber optic couplers are optical devices, dividing one input between two or more outputs, or combining two or more inputs into one output.
The cable type accepted by fiber optic couplers can be could be single mode or multimode.

Choices for coupler type include single window, dual window, or wideband with 1x2, 2x2, 1x3, 3x3, 1x4, 4x4 ports. Also 1x8, 1x16 and 1x32 Star
and tree coupler module are available. 
Devices and Star and tree modules are available.

Such couplers feature Low excess loss, Low PDL, High return loss and excellent reliability and stability. And were widely applicated in LAN, WAN, FTTH
and CATV systems.

Single window couplers are designed for a single wavelength with a narrow wavelength window. 
Dual wavelength couplers are designed for two wavelengths with a wide wavelength window for each. 
Wideband couplers are designed for a single wavelength with a wider wavelength window. 
Wavelength choices for fiber optic couplers include 633 nm, 830 nm, 1060 nm, 1300 nm, and 1550 nm.