Visible-near infrared ultra-broadband polarization-independent metamaterial perfect absorber involving phase-change materials

Abstract

We numerically demonstrate a novel ultra-broadband polarization-independent metamaterial perfect absorber in the visible and near-infrared region involving the phase-change material Ge 2 Sb 2 Te 5 (GST). The novel perfect absorber scheme consists of an array of high-index strong-absorbance GST square resonators separated from a continuous Au substrate by a low-index lossless dielectric layer (silica) and a high-index GST planar cavity. Three absorption peaks with the maximal absorbance up to 99.94% are achieved, owing to the excitation of plasmon-like dipolar or quadrupole resonances from the high-index GST resonators and cavity resonances generated by the GST planar cavity. The intensities and positions of the absorption peaks show strong dependence on structural parameters. A heat transfer model is used to investigate the temporal variation of temperature within the GST region. The results show that the temperature of amorphous GST can reach up to 433 K of the phase transition temperature from room temperature in just 0.37 ns with a relatively low incident light intensity of 1.11 × 10 8 W∕m 2 , due to the enhanced ultra-broadband light absorbance through strong plasmon resonances and cavity resonance in the absorber. The study suggests a feasible means to lower the power requirements for photonic devices based on a thermal phase change via engineering ultra-broadband light absorbers.

Theoretical study of tunable chirality from graphene integrated achiral metasurfaces

“…It should be pointed out that the E F is no larger than 1.0 eV in this study because the breakdown voltage of the dielectric in the structure limits too large biasing voltages [69]. Importantly, our paradigm can tune the CCD spectra in the NIR region from 1990 to 2124 nm (∼7% of the resonance wavelength), and may be more effective compared with tunable/switchable chirality observed in previous investigations that modified the incident angle, structural geometry or material properties [28][29][30][31][32][33][34][35].…”

“…For instance, chirality can be passively switched by tilting the metamaterial against the incident beam [28] or by changing the geometry of the meta-atom [29]. Another way, which has recently attracted considerable attention, is to actively tune the response in chiral metamaterials through external stimuli, such as electric bias [30], temperature [31], or photoexcitation [32,33]. However, most chiral metamaterials integrated with active frequencies due to the low density of injected free electrons for semiconductors outside the THz region [34].…”

Composite Metamaterials for THz Perfect Absorption

“…Artificial metamaterials have extraordinary electromagnetic properties relative to conventional materials and the ability to control incident electromagnetic waves. In addition to many natural materials like polar dielectric and grapheme, metamaterials can be an alternative to surmount the “THz gap.” Since the first metamaterial absorber was shown to have perfect absorption in 2008, absorbers based on metamaterials now range from microwaves to the visible, and have provided direction for THz bands . Most structures consist of a monolayer meta‐surface and a ground plane sandwiched between a medium spacer.…”

Fabrication of Refractive Index Sensors using Polarization Independent Metamaterial and Their Application to Chemical Concentration Measurement and DNA Detection

“…Metamaterials are artificial optical materials with a subwavelength structure smaller than incident wavelength; a number of devices were proposed using novel optical phenomena offered by such materials, for example, negative refractive index, cloaking, luminescence enhancement, ultrathin lenses, perfect absorbers, wavelength-selective filters, etc. [11][12][13][14][15][16][17][18][19][20][21][22] Metamaterials are also known to excite localized surface plasmons and to show high sensitivity to changes in ambient refractive index. [6][7][8][9][10] In addition, high freedom of shape design allows to optimize mode distribution of localized surface plasmons, and to realize high-performance refractive index sensors superior to conventional devices using Au colloids.…”