A novel long reach passive optical networks (LR-PON) with high power budget and high capacity is investigated. Based on self-phase modulation (SPM) induced negative chirp and super-Nyquist image induced aliasing, diversity is firstly introduced to the aliased components using the first-order super-Nyquist image. Then fractional sampling and per-subcarrier maximum ratio combining (MRC) are adopted to harvest the diversity gain. Simulation and experimental results show that, using our proposed scheme, the transmission length of a 10 GHz bandwidth QPSK modulated orthogonal frequency-division multiplexing (OFDM) signal can be extended from 45 km to more than 80 km without any forbidden area. It is also shown that with adaptive modulation, the proposed LR-PON system has a data rate of more than 32 Gb/s and a power budget of larger than 32 dB.