Non-Kirchhoff thermal radiation by cross-groove fan-shaped column array structure driven by magneto-optical phenomenon

To address the common bottlenecks of existing nonreciprocal thermal radiation devices, such as single-polarization dependence and weak nonreciprocity, this paper proposes a dual-polarization nonreciprocal thermal radiator incorporating a periodic array of silicon-based cross-slotted fan-shaped pillars. Working at an external magnetic field of 4 T and an incident angle of 14°, strong nonreciprocal radiation is achieved in the mid-infrared band of 10.5–11 μm. The device exhibits dual-polarization multi-channel operating characteristics, with two nonreciprocal peaks for TE polarization (at 10.8343 and 10.9029 μm) and four for TM polarization (at 10.6246, 10.6867, 10.9259, and 10.9494 μm) within the 10.5–11 μm window. The peak nonreciprocal degrees for TE and TM polarizations can reach 95.27% and 94.77%, respectively, while simultaneously exhibiting excellent narrow-band spectral selectivity. Even at a lower magnetic field of 1 T, the nonreciprocity of TE and TM polarizations can reach 68.2% and 71.5%, respectively, indicating considerable nonreciprocal performance in low-magnetic-field environments. Combined with the rigorous coupled-wave analysis and coupled-mode theory, the nonreciprocal effect is revealed to be the synergistic effect of cavity resonance excitation and guided-mode resonance excitation by the cross-slotted structure. The proposed device achieves dual-polarization ultra-high nonreciprocal radiation at a 14° angle of incidence, offering applications in fields like infrared stealth, thermophotovoltaics, and radiative cooling.