A digital coherent receiver employing photonic downconversion is presented and experimentally demonstrated for phase-modulated radio-over-fiber optical links. Photonic downconversion adds additional advantages to optical phase modulated links by allowing demodulation of signals with RF carrier frequencies exceeding the bandwidth of electrical analog-to-digital converter. High spurious-free dynamic range is observed for RF carriers at 5GHz photonically downconverted to 1GHz.