Simultaneously achieved narrowband and ultra-broadband perfect absorption via plasmonic refractory-colloid crystals

Abstract

We propose and demonstrate a novel perfect absorber platform by combining the colloidal crystal and refractory metal layer. Dual-band absorption with the efficiency up to 99.8% (0.336μm) and 99.1% (1.382μm) is achieved. Moreover, the absorption bandwidths are 81 nm and 1237 nm for the two bands in the UV and near-infrared ranges, suggesting the simultaneous achievement of narrowband and ultra-broadband absorption. Furthermore, the resonant wavelengths in the two bands are with the geometric multiples up to 3∼6, indicating the large differential frequency responses. In addition, the absorption properties can be artificially adjusted via the structural parameters. These features can hold potential applications in the nonlinear optics such as frequency multiplication, difference and mixing, and the selective spectral filtering and manipulation, etc.