Two-Dimensional Spatio-Temporal Signal Processing for Dispersion Compensation in Time-Stretched ADC

Abstract

Abstract-Time-stretched analog-to-digital converters (ADCs) have offered revolutionary enhancements in the performance of electronic converters by reducing the signal bandwidth prior to digitization. An inherent limitation of the time-stretched ADC is the frequency-selective response of the optical system that reduces the effective number of bits for ultrawideband signals. This paper proposes a solution based on spatio-temporal digital processing. The digital algorithm exploits the optical phase diversity to create a flat RF frequency response, even when the system's transfer function included deep nulls within the signal spectrum. For a 10× time-stretch factor with a 10-GHz input signal, simulations show that the proposed solution increases the overall achievable signal-to-noise-and-distortion ratio to 52 dB in the presence of linear distortions. The proposed filter can be used to mitigate the dispersion penalty in other fiber optic applications as well.Index Terms-Analog-to-digital conversion (ADC), optical signal processing, spatio-temporal digital processing, time-stretched converters.

High sensitivity photonic time-stretch electro-optic sampling of terahertz pulses

“…Hence -in addition to the detection of THz fields -this also opens new ways for improving the SNR in electron bunch shape measurements systems for accelerators and free-electron lasers. Further relevant works may concern the association of the present scheme with the so-called amplified time-stretch strategy 10 (with the aim to further enhance detectivity), as well as extending the THz detection bandwidth, using e.g., phase diversity 5,6,34 . Last but not least, reduction of the setup cost may be possible, e.g., by replacing the PM fiber with an SM fiber if a system with circulators can be implemented efficiently 35 .…”

Photonic time‐stretch digitizer and its extension to real‐time spectroscopy and imaging

“…The phase diversity technique with MRC has been used to demonstrate an ultra‐wideband TSADC with an ideal impulse response . When the chirp factor and dispersion parameters of the link are not exactly known, an adaptive two‐dimensional spatio‐temporal signal processing algorithm can be employed to mitigate dispersion penalty fading . The MRC technique ignores the nonlinearities added due to the non‐linear MZM transfer function and dispersion that are discussed in Section .…”