GIGALIGHT 40G QSFP+ ER4 optical transceiver module is designed for long-distance interconnections in data centers. It complies with the IEEE 802.3bm 40GBASE-ER4 Ethernet transmission protocol and supports both 40GE and OTU3 dual-rate applications, which features an integrated pair of multiplexers (MUX) and demultiplexers (DEMUX), with each channel operating at a center wavelength of 1271nm, 1291nm, 1311nm, and 1331nm respectively. It utilizes a pair of single-mode fibers for transmission, allowing for a maximum reach of 40km.