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Orthogonal frequency division multiple access (OFDMA) uplink in a passive optical network (PON) requires the delay alignment for OFDMA symbols from remotely distributed optical network units (ONUs). In this paper, we experimentally demonstrate and analyze the performance of a Zadoff-Chu (ZC) sequence-based upstream ranging scheme in an intensity modulation/direct detection (IM/DD)-based OFDMA-PON. The experimental results show that the proposed scheme can achieve upstream synchronization with only marginal inter-carrier interference (ICI) and requires no additional bandwidths in a typical OFDMA transmission with cyclic prefix (CP).

This paper demonstrates and characterizes a novel wavelength-tunable single-frequency erbium-doped fiber ring laser incorporating an all-fiber acoustooptic tunable bandpass filter and a self-constructed saturable absorption grating (SAG). Stable single-longitudinal-mode operation was achieved over the wavelength range of 48 nm with a sidemode suppression ratio higher than 50 dB. The wavelength tuning characteristics, and the laser dynamics in wavelength switching and sweeping are analyzed in detail. A theoretical analysis on the effect of the SAG is also described.