Topological winding guaranteed coherent orthogonal scattering

Coherent control has enabled various novel phenomena in wave scattering. We\nintroduce an effect called coherent orthogonal scattering, where the output\nwave becomes orthogonal to the reference output state without scatterers. This\neffect leads to a unity extinction coefficient and complete mode conversion. We\nexamine the conditions for this effect and reveal its topological nature by\nrelating it to the indivisibility between the dimension and the winding number\nof scattering submatrices. These findings deepen our understanding of\ntopological scattering phenomena.\n