Reduced sensitivity to disorder in a coupled-resonator waveguide with disordered coupling coefficients

Disorder and structural imperfections are unavoidable and challenge wave engineering. Therefore, methods to reduce disorder and its effects are persistently sought for. Here, we theoretically explore a kind of a bulk mode that is supported by a periodic coupled resonator waveguide with odd length. Although it is a bulk mode, its eigenfrequency is unaffected by disorder, and furthermore, its corresponding eigenvector is stationary under the influence of moderate disorder. Therefore, as we prove analytically and demonstrate numerically, the resonant transmission near its eigenfrequency exhibits substantially reduced sensitivity to disorder compared to any other frequency in the passband.