High frequency optically coherent analog antenna links

In this work we report the demonstration of the first coherent fiber-optic delay line which can introduce true time delays for signals from 0.8 GHz to 1.5 GHz. The frequency range in our experiments is only limited by the Mach-Zehnder modulator employed. The spurious free dynamic range limited by the third order inter-modulation (IM) distortion around 1 GHz is about 80 dB/Hz^2/3, for a 5μW optical signal power and 80 pW local oscillator power. It is expected to be 100 dB/Hz^2/3 or higher if a balanced receiver is used, and both the LO (local oscillator) and signal optical power are increased. We also describe a four-channel system to demonstrate the full delay switching mechanism.