The first demonstration of on-chip quadplexer for passive optical network systems

An on-chip quadplexer is proposed and demonstrated with four wavelength-channels of 1270, 1310, 1490, and 1577 nm. The present quadplexer consists of four cascaded filters based on multimode waveguide grating (MWG), which are composed of a two-mode (de)multiplexer and an MWG. For the fabricated quadplexer on silicon, all four wavelength channels have flat-top responses with low excess losses of <0.5  dB as well as the desired bandwidths, which are about 16, 38, 19, and 6 nm, respectively. The cross-talk for both upstream channels and downstream channels is less than −24  dB. Moreover, the data transmission of 10  Gb/s of the present silicon quadplexer is also successfully demonstrated.