  The reflectionless coherent light transport in the coupled resonator array is
investigated in the presence of intra-resonator intermodal coupling between the
clockwise and counterclockwise modes, which plays a constructive role for
modulating the light flow rather than inducing the unwanted backscattering. The
interplay between the intra-resonator intermodal coupling and the
inter-resonator couplings enables the coherent resonant transmission (CRT) of
the properly superposed injection constituted by the clockwise and
counterclockwise modes. The superposition coefficients of the initial
excitation determine the mode chirality of the resonant transmission.
Sequentially experiencing the time-reversal process of CRT and the CRT realizes
the perfect mode conversion that the mode chirality of the injection wave
switches into the opposite after resonant transmission. Our findings on the
coherent light transport provide insights for the control and manipulation of
light field in the integrated photonics, nanophotonics, chiral optics, and
beyond.
