Abstract—
Recently, optical phase modulation has been widely
used in microwave photonics (MWP) systems, such as radio
over fiber systems, photonic microwave filters, optical microwave
and millimeter-wave signal generators, and optical subcarrier
frequency up-converters. An optical phase-modulated signal can
be converted to an intensity-modulated signal in a dispersive
optical fiber. Due to the intrinsic nonlinearity of optical phase
modulation, for linear applications such as microwave signal distribution
and filtering, the modulation index should be kept small
to minimize the unwanted modulation nonlinearity. However, for
nonlinear applications such as microwave frequency multiplication
and subcarrier frequency upconversion, the modulation
index should be large to maximize the frequency multiplication
and upconversion efficiency. In this paper, for the first time to
our knowledge, we develop a thorough theoretical framework for
the characterization of phase-modulation-based MWP systems, in
which the phase modulation to intensity modulation conversion
is realized using a dispersive fiber. Analytical models for the
distributions of single-tone and two-tone microwave signals and
for microwave frequency multiplication and subcarrier frequency
upconversion are developed, which are verified by numerical
simulations. The analytical models for single-tone and two-tone
transmissions are further confirmed by experiments. The developed
analytical models provide an accurate mathematical tool in
designing phase-modulation-based MWP systems.
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