Fig. 1. Proposed optical phase remodulation architecture. EDFA: erbium-doped fiber amplifier; PM: phase modulator; PIN: p-i-n receiver; MUX: multiplexer; DEMUX: de-multiplexer.

Fig. 2. Eye diagrams with different downstream MDs: (a)–(c) downstream DPSK signal, demodulated from the destructive port of the DI; (d)–(f) DPSK signal in the downstream, demodulated from the constructive port of the DI; (g)–(i) downstream OOK signal in the conventional optical amplitude remodulation scheme.

Fig. 3. (a) Insertion loss for the destructive port of the DI for the RMD-DPSK signal in the downstream, at different downstream MDs. Inset: the simulated spectrum of the RMD-DPSK signal in the downstream with different MDs. (b) Impact of the downstream MD on the receiver sensitivity of both the downstream and upstream signals when using different remodulation schemes. Detected eye diagrams of the FMD-DPSK signal in the upstream (c) when using the constructive port output from the DI as the upstream carrier and (d) when using part of the RMD-DPSK data in the downstream as the upstream carrier. (e) Detected eye diagrams of the FMD-OOK signal in the upstream when using conventional optical amplitude remodulation. The downstream MD in (c)–(e) is 0.4.

Fig. 4. (a) Experimental setup used to study the effect of the DI’s two output ports on RBS suppression. CP, constructive port; DP, destructive port. (b)–(d) Measured spectra of the RBS before and after the DI when the downstream MDs are 0.18, 0.31, and 0.43, respectively (resolution bandwidth=0.06nm).

Fig. 5. (a) Eye diagrams of the detected downstream RMD-DPSK and upstream FMD-DPSK signals in the B2B and transmission cases. DS, downstream; US, upstream. (b) BER measurement results when the downstream MD is 0.22. (c) BER measurement results when the downstream MD is 0.18 and an SOA is used at the ONU.