Dynamically tunable coherent perfect absorption based on bulk Dirac semimetal

Abstract

Coherent perfect absorption (CPA) is realized in metasurfaces composed of crossed vertical bulk Dirac semimetal (BDS) stripes and S i O 2 . Under the illumination of two counter-propagating coherent beams, the coherent absorption is continuously controlled from almost 0 (approximately 6.2 × 10 − 5 ) to 99.97% by changing the beams’ relative phase, which gives a modulation depth of about 1.6 × 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.

Dynamically tunable multi-band coherent perfect absorption based on InSb metasurfaces

“…completed, the operating frequency and absorption efficiency of the absorber are difficult to flexibly control, which hinders its practical application. Coherent perfect absorption (CPA) provides a viable method for achieving tunable absorption in metasurfaces, with additional flexibility to control the two beams separately [11][12][13][14][15][16][17][18][19]. The coherent absorption characteristic strongly depends on the spatial position of the metasurface in the standing wave.…”

“…When the metasurface is placed at the antinode or node of the standing wave, the electromagnetic response can be selectively enhanced or suppressed. This provides a novel method to realize the dynamic tunable perfect absorption of the micro-nano structure, which have been realized based on metamaterials [12,14,15,18,19], thin films [11,16], and waveguides [13,17]. Simultaneously, coherent absorption has potential applications in manipulating the direction of electron movement in semiconductors [20] and optical positioning [21].…”