Analog predistortion technique in remodulation based radio over high-speed access network for improving sensitivity

Abstract

We demonstrate an RSOA-based WDM-PON using a spectrally distorted 622-Mbps Sub-carrier Multiplexing (SCM) signal at 1200-MHz for downstream and a 622-Mbps Non Return to Zero (NRZ) signal for upstream. Even though the overall transmission bandwidth for the SCM signal with transceivers originally for 1.25-Gbps is only 810-MHz, a clear eye opening can be obtained using a spectral predistortion technique to compensate the signal quality deterioration above 810-MHz. With the predistorter, downstream signal sensitivity is improved up to 1.4-dB, leading to a wider range of the optical modulation index of the downstream SCM signal.