Compact Optical Sampler for Broadband Wireless Signals

Sampling is the first step in analog-to-digital conversion (ADC) and especially the photonic assistance of electronic ADCs may be a viable solution to address the bottleneck in processing the envisioned peak data rates of 1 Tbit/s for 6G and beyond wireless communication. Here integrated cascaded ring modulators (RMs) are proposed for the ultra-compact and energy-efficient optical down sampling of broadband wireless signals. The N time-interleaved, low-bandwidth sub-signals, can then be detected and processed with low-bandwidth electronics. This method is superior to electronic sample-and-hold circuits as it introduces no aperture jitter since it relies on multiplication rather than switching. In a proof-of-concept experimental demonstration with integrated cascaded ring modulators with an 18 GHz electro-optic bandwidth, a Nyquist sampling rate of 36 GSa/s is shown with a 12 GHz oscillator and
$N = 3$
. Furthermore, the demonstrated system is capable of offering a sampling rate of 60 GSa/s for the 18 GHz wireless signals. Since RM designs with bandwidth exceeding 50 GHz have been shown in the literature, the proposed system could enable compact and energy-efficient Tbit/s wireless communication devices.