Photonic-Assisted Analog-to-Digital Conversion Based on a Dispersion-Diversity Multicore Fiber

Multigigabit-per-second photonic-assisted time-interleaved analog-to-digital conversion (ADC) built upon a dispersion-diversity multicore fiber (MCF) is proposed and experimentally demonstrated for the first time to our knowledge. Tunable true-time delay line operation for the analog signal replicas is provided by the different cores of a heterogeneous MCF, which feature different radial dimensions and GeO
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dopant concentrations. Continuous real-time ADC tunability with the optical wavelength is experimentally demonstrated by time interleaving 5 digitized channels achieving equivalent sampling rates of 25, 50 and 125 GS/s for optical wavelengths of 1538, 1534 and 1531.6 nm, respectively. These values are beyond the 10.25-GS/s sampling rates offered by commercial electronic ADCs. One of the advantages of using a MCF for the parallel channels relies on the fact that all the cavities are subject to similar environmental conditions. The introduction of space and dispersion diversities provided by MCFs in photonic-assisted ADCs brings benefits in terms of size, weight, and power consumption reduction along with system flexibility and stability improvement. This is of particular relevance in those application scenarios where an optical fiber link is required to distribute the signal, such as fiber distributed sensing networks, as well as access networks for radar systems or next-generation wireless communications.