Dynamically tunable coherent perfect absorption based on bulk Dirac semimetal

Coherent perfect absorption (CPA) is realized in metasurfaces composed of crossed vertical bulk Dirac semimetal (BDS) stripes and SiO2. Under the illumination of two counter-propagating coherent beams, the coherent absorption is continuously controlled from almost 0 (approximately 6.2 x 10(-5)) to 99.97% by changing the beams' relative phase, which gives a modulation depth of about 1.6 x 10(4). Furthermore, the coherent absorption can be controlled substantially by varying the relative intensity, the Fermi energy of BDS, and the structural parameters of the metasurfaces. Further research shows that the metasurface has broadband angular selectivity: CPA frequency splits into TE and TM polarization bands under oblique incidence. Our results provide an effective way to manipulate the interaction of light and BDS, and there may be potential applications in coherent detectors and optical modulators. (C) 2020 Optical Society of America