Constant topology sound enhancement sensor based on acoustic heterostructure and construction method thereof

The invention discloses a constant topology acoustic enhancement sensor based on an acoustic heterostructure and a construction method thereof, the acoustic enhancement sensor comprises two basic phononic crystal units with different band gap widths, each basic phononic crystal unit comprises 2N + 1 rectangular waveguide tubes which are connected in sequence, N is a positive integer greater than or equal to 1, and N is a positive integer greater than or equal to 1. The rectangular waveguide tubes have the same width b; the total length of the basic phononic crystal unit is a fixed value a, and the basic phononic crystal unit is in mirror symmetry about the central section of the basic phononic crystal unit on the whole and has a variable section along the length direction; the two basic phononic crystal units are spliced end to end; when the frequency is adjusted, the structural parameter of one basic photonic crystal unit is kept unchanged, the length parameter of the rectangular waveguide tube in the middle