The JDSU interleaver is a terabit-enabling technology for ultradense wavelengthdivision multiplexing (DWDM) applications. When used in the mux configuration, the interleaver combines two streams of periodic optical signals (one stream carries even channels and the other carries odd channels) into one stream of signals of half the channel spacing. When used in the demux configuration, the signal is separated into two complementary streams (even and odd channels) of twice the channel spacing. The low dispersion interleaver, based on patented technology, features a wide clear bandwidth, minimal thermal drift, low insertion loss, low ripple, and low polarization dependent loss (PDL). Temperature control is not required.