Coherent Optical Phase-Modulation Link

We demonstrate and characterize a new class of radio-frequency (RF)-photonic link for the linear transport of analog RF signals. Simultaneous and separate detection and digitization of optical in-phase and quadrature-phase signals is employed for linear phase demodulation in the digital domain. This is shown to allow significantly larger tolerance to imperfect physical implementation of the phase demodulating receiver. Digitizer-limited spur-free dynamic range improvement >12 dBldrHz
^2/3
is observed in our baseband demonstration. Modulation depths significantly exceeding unity are allowed and demonstrated.