  In this paper, we experimentally demonstrate reversible wavefront shaping
through mimicking gravitational field. A gradient-index micro-structured
optical waveguide with special refractive index profile was constructed whose
effective index satisfying a gravitational field profile. Inside the waveguide,
an incident broad Gaussian beam is firstly transformed into an accelerating
beam, and the generated accelerating beam is gradually changed back to a
Gaussian beam afterwards. To validate our experiment, we performed full-wave
continuum simulations that agree with the experimental results. Furthermore, a
theoretical model was established to describe the evolution of the laser beam
based on Landau's method, showing that the accelerating beam behaves like the
Airy beam in the small range in which the linear potential approaches zero. To
our knowledge, such a reversible wavefront shaping technique has not been
reported before.
