Thorlabs offers 1x2 graded-index (GRIN) multimode, dual-window fiber couplers withØ62.5 µm core graded-index fibers. These couplers operate at both 850 ± 40 nm and1310 nm ± 40 nm wavelengths. Couplers are available with 50:50, 75:25, 90:10, or 99:1split ratios, either unterminated or with 2.0 mm narrow key FC/PC connectors. All fiberleads are 0.8 m long and are jacketed in Ø900 µm loose tubing. Additionally, eachcoupler ships with an individual test report; click here for a sample.1x2 couplers are manufactured using the same process as our 2x2 fiber optic couplers, but have only one input port for simplified use and cable management.These couplers are ideal for applications where light is split from the input port into two output ports at the specified coupling ratio but are not recommended forcombining applications due to losses in power. The unused port is internally terminated within the coupler housing in a manner that minimizes back reflections(please see the 1x2 Coupler Tutorial tab for details).