Computational and experimental investigations on electronic and optical response of oxygenated MoS2

The current study is concerned with the first principle investigations of the oxygenated MoS2 to explore the electronic and optical properties. We consider various oxygen concentrations (MoS2, MoS1.75O0.25, MoS1.5O0.5, MoSO) for the prediction of its impact on parameters using PBE-GGA approximation. A noticeable change in parameters has been observed in the visible regime with the introduction of oxygen content in the MoS2 structure. The results of the electronic properties suggest a string role of Mo d-states, S p-states, and O p-states which, however, show variations for various O concentrations near the Fermi level. In comparison to the absorption trend of pure MoS2, the optical absorption spectra show a blue shift in the visible range. The effect of oxygen can also be seen in the experimentally prepared MoS2 thin films as the variation of optical behavior can be seen. Refractive index decreases from ~2.5 to ~2. Similarly, absorption graphs show a lack of absorption phenomenon as the oxygen content increases. The role of oxygen brings appreciable changes in the optical parameters over the different energy ranges.

Development of Single layered, Wide angle, Polarization insensitive Metamaterial Absorber

The simultaneous achievement of multiband absorption, polarisation-insensitive, and angularly stable absorber is a difficult job. Therefore, in this article, an efficient single-layered absorber is designed, critically analysed, fabricated, and experimentally validated. The proposed model incorporates eight sectors loaded a circle inside the square. The four discrete absorption peaks are observed at 4.4 GHz, 6.0 GHz, 14.1 GHz, and 16.0 GHz manifesting absorption intensities of 94%, 84%, 82%, and 92%, respectively. Parametric studies have been also exercised to investigate the influence of discrete geometrical design variables on the proposed absorber. The proposed structure is symmetrical in geometry, consequence in polarisation-independent behaviour. The absorption mechanism is also explained by analysing the surface current, electric field, and magnetic field distributions. Besides, the complex electromagnetic parameters are extracted to realise the absorption phenomenon. Additionally, to validate the simulated results, an optimal sample is fabricated and the measured response is well-matched with simulated ones.

Holmium(iii) molecular nanomagnets for optical thermometry exploring the luminescence re-absorption effect

HoIII complexes bearing organic luminophores and inorganic metalloligands are an effective tool for achieving the unique conjunction of single-molecule magnetism and thermometric luminescence re-absorption phenomenon.

Characterization of Optically-Reconfigurable Metasurfaces by a Free Space Microwave Bistatic Technique

Microwave performance extraction of optically-controlled squared frequency-selective surface (FSS) structures printed on highly resistive (HR) silicon substrate are presented, from a innovative bistatic microwave photonic characterization technique operating in the 40 to 60 GHz frequency range, commonly used for radar cross section (RCS) measurements. According to typical physical photon absorption phenomenon occurring in photoconductive materials, these structures demonstrate experimentally a bandpass filtering frequency response cancellation through reflection coefficient measurements, under specific incident collective illumination in the Near-infrared region (NIR). This behaviour is attributed to their microwave surface impedance modification accordingly to the incident optical power, allowing ultrafast reconfigurability of such devices by optics

Inter and intra band impurity-related absorption in (In,Ga)N/GaN QW under composition, size and impurity effects

In this paper, we theoretically investigate the impacts of Internal well composition, size and impurity's position on the inter valence-conduction bands and intra conduction band optical absorption in GaN/(In,Ga)N/GaN hetero-structure. Based on the numerically finite element method (FEM), the impurity's related Schrödinger equation is solved for the finite potential barrier considering the dielectric constant and effective-mass mismatches between the well and its surrounding matrix. Our results show that the absorption is strongly governed by the dipole matrix element and initial and final implied states transition energies. For a fixed barrier width, the absorption spectra are found red-shifted (blue-shifted) with increasing the well width (In-concentration). It is also shown that the impurity's absorption phenomenon is more pronounced for the off-center case compared to the on-center one. We conclude that the proper control of these parameters is required to best understanding of the optical absorption for solar cell applications.