Turbulence is a complex spatiotemporal behavior and a fundamental concept in fluid dynamics,
which has been extended to other systems out of equilibrium, such as nonlinear optics, chemistry,
active matter, and economics. Fingerprint patterns with sustained spatiotemporal dynamics in a
liquid crystal light valve with an optical feedback experiment are studied. We show that the light intensity
field presents a dynamical regime simultaneously exhibiting phase and amplitude turbulence.
This bi-turbulent behavior of patterns is characterized by power-law spectra with exponents close
to -2 and -3 spatially and -2 temporally, for the phase and amplitude respectively. The pattern
orientation field also presents power-law spectra with exponents close to -2 and -3/4, spatially
and temporally. We characterize the observed chaotic dynamics by estimating the largest Lyapunov
exponent. We provide a theoretical model of pattern formation that explains the experimental
observations with good qualitative agreement.
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