Dual-band and spectrally selective infrared absorbers based on hybrid gold-graphene metasurfaces.

In this paper, we propose a dual-band and spectrally selective infrared (IR) absorber based on a hybrid structure comprising a patterned graphene monolayer and cross-shaped gold resonators within a metasurface. Rooted in full-wave numerical simulations, our study shows that the fundamental absorption mode of the gold metasurface hybridizes with the graphene pattern, leading to a second absorptive mode whose properties depend on graphene's electrical properties and physical geometry. Specifically, the central operation band of the absorber is defined by the gold resonators whereas the relative absorption level and spectral separation between the two modes can be controlled by graphene's chemical potential and its pattern, respectively. We analyze this platform using coupled-mode theory to understand the coupling mechanism between these modes and to elucidate the emergence and tuning of the dual band response. The proposed dual-band device can operate at different bands across the IR spectrum and may open new possibilities for tailored sensing applications in spectroscopy, thermal imaging, and environmental monitoring.

Utilization of smartphones for the evaluation of Gr/Ni nanostructures magnetically controlled based on optical fibers surface plasmons.

In the suggested optical fiber-based magnetoplasmonic system, we investigated the magnetic properties of graphene/nickel nanostructures. The plasmonic mode changes under the magnetic field observed in the intensity diagrams over time. To be accessible, cheap, and portable, we used a smartphone as a detector and processor. Considering the ambient noise and the light source, it was reported that the intensity of the changes improved up to 5 times. Further, the clad corrosion experiment carried out by pure dimethyl ketone in an intensity modulation by a smartphone camera and 10 seconds suggested removing fluorine polymer clad.

Enhancement of methane gas sensing characteristics of graphene oxide sensor by heat treatment and laser irradiation.

The present study uses a rapid, easy and practical method for cost-effective fabrication of a methane gas sensor. The sensor was made by drop-casting a graphene oxide suspension onto an interdigital circuit surface. The electrical conductivity and gas-sensing characteristics of the sensor were determined and then heat treatment and in situ laser irradiation were applied to improve the device conductivity and gas sensitivity. Real-time monitoring of the evolution of the device current as a function of heat treatment time revealed significant changes in the conductance of the graphene oxide sensor. The use of low power laser irradiation enhanced both the electrical conductivity and sensing response of the graphene oxide sensor.