Broadband Terahertz Absorption in Graphene-Embedded Photonic Crystals

The absorption in graphene is rather low at terahertz frequencies. Here, we present a graphene-embedded photonic crystal structure to realize broadband terahertz absorption in graphene. The approach provides absorption enhancement in the whole terahertz regime (from 0.1 to 10 THz). It is shown that the average absorption in the graphene-embedded photonic crystal can be enhanced in the multiple propagating bands of the photonic crystals. The absorption efficiency can be further improved by optimizing the characteristic frequency, optical thickness ratio in a unit cell, and the angle of incidence on the photonic crystals. A maximum broadband absorption factor of 28.8% was achieved for fixed alternative dielectric materials. The graphene-embedded photonic crystal is promising for terahertz functional devices with broadband response.