Splitting of self-collimated beams in two-dimensional sonic crystals

Abstract

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.Comment: 12 pages, 8 figure

2D phononic-crystal Luneburg lens for all-angle underwater sound localization

“…Recently, underwater acoustic metamaterial [1][2][3][4][5] attracts a lot of attention because its function of wave manipulation has potential applications in underwater technology, and a new crossing field may come out. As an initial version of acoustic metamaterial, the phononic crystal that is a periodic structure made of multiple mediums or a single-phase artificial microstructure enables negative refraction [6], wave bending [7], and splitting [8] to be realized. Due to the excellent performance of waveguide, phononic crystal is used for acoustic wave focusing [9][10][11], and the fabricated device is always named phononic-crystal lens.…”

One-way Acoustic Beam Splitter

“…demonstrate an acoustic BS by introducing a line defect structure, which allows for tuning the splitting efficiency by varying the radius of the rods in the PnC 9 . The line-defect-based mechanism for acoustic beam splitting in PnCs has been generalized to have multiple outputs by employing more line defects 10 . A defect-free beam splitting device is also proposed at the low GHz frequency regime, which provides a possible way to relax the limitations on the excitation source 11 .…”

Flexibly guiding of acoustic waves by one-dimensional sonic crystal with omnidirectional bandgap

“…Broadband and low-loss guiding can be achieved and the designing degree of freedom in such SCWs can be further improved by grafting some additional structures such as stubs or cavities to the sidewall of the waveguide. Another method to realize SCWs is to adopt self-collimating of 2D SCs, [8][9][10][11] in which guiding of acoustic waves relies on a well designed spatially-dependent dispersion but not the existence of a bandgap. Extensions like bending or splitting for such self-collimating waveguides can be achieved by introducing extra structures into SCs.…”