Characterization of the frequency response of channel-interleaved photonic ADCs based on the optical time-division demultiplexer

TL;DR

This paper analyzes the frequency response of channel-interleaved photonic ADCs, revealing how photonic sampling and OTDM influence bandwidth and response characteristics through theoretical and experimental methods.

Contribution

It provides a comprehensive characterization of the frequency response of CI-PADCs, highlighting the role of OTDM in bandwidth enhancement and response behavior.

Findings

Frequency response divided into multiple intervals based on demultiplexed pulse train repetition rate.

Analog bandwidth determined by the spectral bandwidth of demultiplexed pulse trains.

OTDM significantly enlarges the bandwidth of photonic ADCs with limited spectral bandwidth pulses.

Abstract

We characterize the frequency response of channel-interleaved photonic analog-to-digital converters (CI-PADCs) theoretically and experimentally. The CI-PADC is composed of a photonic frontend for photonic sampling and an electronic backend for quantization. The photonic frontend includes a photonic sampling pulse generator for directly high-speed sampling and an optical time-division demultiplexer (OTDM) for channel demultiplexing. It is found that the frequency response of the CI-PADC is influenced by both the photonic sampling pulses and the OTDM, of which the combined impact can be characterized through demultiplexed pulse trains. First, the frequency response can be divided into multiple frequency intervals and the range of the frequency interval equals the repetition rate of demultiplexed pulse trains. Second, the analog bandwidth of the CI-PADC is determined by the optical spectral bandwidth of demultiplexed pulse trains which is broadened in the OTDM. Further, the effect of the OTDM is essential for enlarging the analog bandwidth of the CI-PADC employing the photonic sampling pulses with a limited optical spectral bandwidth.