  A photonics-assisted joint communication-radar system is proposed and
experimentally demonstrated, by introducing a quadrature phase-shift keying
(QPSK)-sliced linearly frequency-modulated (LFM) signal. An LFM signal is
carrier-suppressed single-sideband modulated onto the optical carrier in one
dual-parallel Mach-Zehnder modulator (DPMZM) of a dual-polarization
dual-parallel Mach-Zehnder modulator (DPol-DPMZM). The other DPMZM of the
DPol-DPMZM is biased as an IQ modulator to implement QPSK modulation on the
optical carrier. The polarization orthogonal optical signals from the
DPol-DPMZM are further combined and detected in a photodetector to generate the
QPSK-sliced LFM signal, which is used to realize efficient data transmission
and high-performance radar functions including ranging and imaging. An
experiment is carried out. Radar range detection with an error of less than 4
cm, ISAR imaging with a resolution of 14.99 cm*3.25 cm, and communication with
a data rate of 105.26 Mbit/s are successfully verified.
