Signal Reconstruction by Phase Retrieval and Optical Backpropagation in Phase-Diverse Photonic Time-Stretch Systems
Journal article, 2007
The signal-to-noise ratio and bandwidth of photonic
time-stretch (PTS) systems have previously been limited due to the
nonlinear distortion caused by modulator response and dispersive
propagation. In this paper, we present a novel method for the
reconstruction of the input signal from two phase-diverse intensity
measurements. The method consists of optical phase retrieval at
the measurement point followed by simulated optical backpropagation
to the modulation point. By numerical simulation of a PTS
system with realistic parameters, we analyze the proposed method
and compare it with the previously suggested maximum ratio
combining (MRC) method. We show that the proposed optical
backpropagation method, unlike the MRC method that treats
the system as being linear from electrical input to output, can
reconstruct the signal even at a large modulation depth and that
the method is insensitive to biasing error or drift and not overly
sensitive to misestimation of system parameters. Furthermore, to
reduce the computational effort associated with the simulation
of PTS systems, we present a numerical propagation method
whereby the required number of sampling points is reduced by
several orders of magnitude.
optical propagation in dispersive media
fiber optics
Analog-to-digital (A–D) conversion
optical signal processing
photonic A–D converter
microwave photonics
photonic sampling