We proposed and experimentally demonstrated a wavelength-space division multiplexing (WSDM) optical access network architecture with centralized optical carrier delivery utilizing multicore fibers (MCFs) and adaptive modulation based on reflective semiconductor amplifier (RSOA). In our experiment, five of the outer cores are used for undirectional downstream (DS) transmission only, while the remaining outer core is utilized as a dedicated channel to transmit upstream (US) signals. Optical carriers for US are delivered from the OLT to the ONUs via the inner core and then transmitted back to the OLT after amplification and modulation by the RSOA in the colorless ONU side. The mobile backhaul (MB) service is also supported by the inner core.

Wavelengths used in US transmission should be different from that of the MB in order to avoid the Rayleigh backscattering effect in bidirectional transmission. With QPSK-OFDM modulation format, the aggregation DS capacity reaches 250Gb/s using 5 outer cores and ten wavelengths, and it can be further scaled to 1Tb/s using 20 wavelengths modulated with 16QAM-OFDM. For US transmission, 2.5Gb/s QPSK-OFDM transmission can be achieved just using a low-bandwidth RSOA and adaptive modulation is applied to the RSOA to further enhance the US data rate to 3.12Gb/s. As an emulation of high speed MB transmission, 48Gb/s IQ modulated PDM-QPSK signal is transmitted in the inner core of MCF and coherently detected in the OLT side. Both DS and US optical signals exhibit acceptable performance with sufficient power budget.

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