Near field radiative heat transfer in asymmetric three-grating systems

•Near-field radiative heat transfer is theoretically investigated in asymmetric three-grating systems.•The forward and reverse scenarios in asymmetric three-grating systems provide a high flexibility of manipulation the heat transfer rate.•The difference in the coupling of evanescent modes on two sides of the asymmetric modulator is responsible for significantly changing the performance.•The temperature of modulator can be viewed as a signal of the coupling of modes in different channels. The investigations of near field radiative heat transfer have been extended to many-body systems for further improving the heat transfer rate. Here, we develop a general formulation for characterizing near field radiative heat transfer in three-grating systems, which can be applied in asymmetric scenarios. By introducing asymmetric modulators between thermal emitters and absorbers, we show a remarkable amplification of heat flux in three-grating systems than two-grating counterparts. Moreover, the forward and reverse scenarios in asymmetric three-grating systems provide a high flexibility of manipulation the heat transfer rate, ascribed to the difference in the coupling of evanescent modes on two sides of asymmetric modulator. The proposed formulation and the designed near field radiative heat transfer systems may pave a new avenue for further enhance and modulate heat transfer rate in many penitential applications.