  An easy-to-implement scheme to split self-collimated acoustic beams in sonic
crystals (SCs) is proposed by introducing line-defects into SCs, by which an
incoming self-collimated beam can be split into a 90 degree-bended one and a
transmitted one with an arbitrary power ratio by adjusting the value of defect
size. An all-angle and wide-band splitting instrument is demonstrated with
nearly perfect efficiency (more than 90%) for Gaussian beams at a wide range of
incident angles. Splitting effect for a point source as input is also realized,
in which two subwavelength images of the source, i.e., a bended one and a
transmitted one, are formed by our designed splitting structure. Finally, the
proposed one-to-two splitting scheme is generalized to one-to-N (N>2) cases by
inserting more rows of line defects into the SC.
