Optical Circulator

Optical Circulator for 40G QSFP / 100G QSFP28 Modules, 1310 

40G QSFP / 100G QSFP28 (1270, 1290, 1310, 1330) over a single fiber.

Optical Circulator Application Diagram

40G QSFP LR4
100G QSFP28 CWDM4

QSFP-40G-LR4 1310 nm LC transceivers actually use four wavelengths rather than a single 1310 nm wavelength. These wavelengths are combined through a CWDM multiplexer (1270, 1290, 1310, 1330), which is why such modules are also referred to as QSFP-40G-CWDM4.