Generation of vortex waves in non-coaxial cylindrical waveguides

A non-coaxial waveguide composed of a cylindrical resonator of radius R and cylindrical waveguides with the radii r1 and r2, respectively, is considered. The radii satisfy the inequality r1 < r2 < R. The conversion from the channel with zero orbital angular momentum (OAM) into the channels with non-zero OAM is achieved by shifting the center lines of the waveguides relative to the center line of the cylindrical resonator. The center lines of input and output waveguides are shifted relative to each other by the angle D/ in order to twist the output acoustic wave. The conversion efficiency of the input wave with zero OAM into the output wave with non-zero OAM as dependent on the frequency, length of the resonator, and D/ is considered, and the domains where the efficiency can reach almost 100% are found. (C) 2019 Acoustical Society of America.