Ultra-narrowband absorption enhancement in monolayer transition-metal dichalcogenides with simple guided-mode resonance filters

A simple guided-mode resonance filter composed of a single layer of molybdenum disulfide (MoS 2), a dielectric grating, and a dielectric substrate is designed to enhance light absorption in the visible range. The absorption characteristics of the system are investigated and analyzed by using the rigorous coupled-wave analysis method and the slab waveguide theory. The results reveal that the high absorption over 65% can be obtained for TE polarization and over 53% for TM polarization. Intriguingly, the structure exhibits an ultranarrow absorption bandwidth under TM polarization, the full width at half maximum is only 0.51nm, and the quality factor can be more than 1200. In addition, multichannel absorption can be realized by increasing the thickness of the grating layer. The resonant wavelength can be dynamically selected by merely tuning the incident angle. The proposed device with its simple design can be applied to enhance the absorption of other two-dimensional materials.