Combining DPSK and duobinary for the downstream in 40-Gb/s long-reach WDM-PONs

► We propose combining DPSK and DB transmission in 40-Gb/s long-reach WDM-PONs. ► Multichannel format conversion from DPSK to DB is realized using a single MZDI. ► DPSK reach and DB access transmission are experimentally demonstrated at 40 Gb/s.