  This paper investigates the acoustic Luneburg Lens (ALL) as a design
framework for guiding acoustic wave propagation. In this study, we propose to
develop an acoustic waveguide based on the characteristics of both acoustic
wave focusing and collimation of cascaded ALLs. The continuous variation of
refractive index of the ALL is achieved by using lattice unit cells with a
graded filling ratio. A cascaded ALL waveguide device is fabricated based on
the additive manufacturing technique. The experimental results obtained with
this device are consistent with the numerical simulations and theoretical
calculations.
