Plasmonic improvement photoresponse of vertical-MoS2 nanostructure photodetector by Au nanoparticles

We study graphene on a photonic crystal operating in the terahertz (THz) spectral range. We show that the absorption of graphene becomes a modulated function of frequency and can be enhanced by more than three times at specific frequency values, depending on the parameters of the system. The problem of a semi-infinite photonic crystal is also solved.

Enhancing the absorption of graphene in the terahertz range

Facile, scalable and transfer free vertical-MoS2 nanostructures grown on Au/SiO2 patterned electrode for photodetector application

Abstract Over the past decade, the plasmonics of graphene and black phosphorus (BP) were widely recognized as promising media for establishing linear and nonlinear light-matter interactions. Compared to the conventional metals, they support significant light-matter interaction of high efficiency and show undispersed optical properties. Furthermore, in contrast to the conventional metals, the plasmonic properties of graphene and BP structure can be tuned by electrical and chemical doping. In this review, a deep attention was paid toward the second- and third-order nonlinear plasmonic modes of graphene and BP. We present a theoretical framework for calculating the lifetime for surface plasmons modes of graphene and BP assisted by the coupled mode theory. The effect of the Fermi energy on the second-order and third-order nonlinear response is studied in detail. We survey the recent advances in nonlinear optics and the applications of graphene and BP-based tunable plasmonic devices such as light modulation devices, switches, biosensors, and other nonlinear photonic devices. Finally, we highlight a few representative current applications of graphene and BP to photonic and optoelectronic devices.

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Recent advances in graphene and black phosphorus nonlinear plasmonics

We present theoretical study on developing a one-dimensional (1D) photonic crystal heterojunction (h-PhC) that consists of a monolayer molybdenum disulfide (MoS2) structure. By employing the transfer matrix method, we obtained the analytical solution of the light absorption and emission of two-dimensional materials in 1D h-PhC. Simultaneously enhancing the light absorption and emission of the medium in multiple frequency ranges is easy as h-PhC has more modes of photon localization than the common photonic crystal. Our numerical results demonstrate that the proposed 1D h-PhC can simultaneously enhance the light absorption and emission of MoS2 and enhance the photoluminescence spectrum of MoS2 by 2-3 orders of magnitude.

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Greatly enhanced light emission of MoS2 using photonic crystal heterojunction

Increasing optical absorption in one-dimensional photonic crystals including MoS2 monolayer for photovoltaics applications

2D molybdenum disulfide MoS2, has represented potential applications in optoelectronic devices based on their promising optical absorption responses. However, for practical applications, absorption should increase furthermore in a wide wavelength window. In this paper, we design Fibonacci photonic crystals (PCs) based on Si, SiO2 and MoS2 monolayer and we calculate their absorption responses based on the transfer matrix method. The optical refractive index of the MoS2 monolayer was determined based on the Lorentz–Drude–Gauss model. Effects of Fibonacci order, periodicity, incident light angle and polarization are included in our calculations. Finally, an absorption as large as 90% in a wide optical wavelength range is achieved for both polarizations and incident angle down to 60°. Our results are useful for designing photonic devices with high absorption efficiency.

https://iopscience.iop.org/article/10.1088/1361-6463/aaacbd/pdf

Broadband and high absorption in Fibonacci photonic crystal including MoS2 monolayer in the visible range

Two-dimensional transition metal dichalcogenides (TMDCs) with direct bandgap and high optical absorption have opened a new horizon in photonics and optoelectronics. Increasing their absorption could greatly benefit their application, a subject still under debate. Thus, this study was focused on the plasmonic effect mediated by a thin gold layer and the role of individual spacer and cover layers or their combination in structures that include TMDC monolayers, namely, cover/TMDC/spacer/Au/substrate multilayers. The optical properties of these structures were investigated via the transfer matrix method in the visible wavelength region, revealing absorption values up to 99%. Such structures could be applied in the design of efficient optical absorbers for high-performance photovoltaic devices.

Nearly perfect and broadband optical absorption by TMDCs in cover/TMDC/spacer/Au/substrate multilayers

In recent years, two-dimensional materials such as MoS2 monolayers have attracted a lot of attention due to their high absorption. This study proposes the use of MoS2 monolayers as part of the defect in Fibonacci and Thue-Morse defective quasiphotonic crystals (DQPCs) to create an adjustable defect mode with relatively high absorption. The wavelength adjustability of the defect mode is investigated by parameters such as generation number, periodicity, and type of sequence used in DQPCs. The results revealed that using DQPCs can help enhance absorption and enables the adjustment of the defect mode as its generation number changes. Moreover, a Fibonacci DQPC generally requires much fewer layers in comparison to a Thue-Morse DQPC. To conclude, it is possible to achieve a wavelength-adjustable absorption of more than 90% with a Fibonacci DQPC.

Approaching the nearly perfect and wavelength-adjustable absorption of MoS2 monolayer using defective quasi photonic crystals

Among ultrathin transition metal dichalcogenides, WS2 monolayers with a direct bandgap have attracted intensive attention because of their narrow optical absorption centered at 619 nm. However, these layers with stronger absorption are needed in applications such as photonic devices. In this paper, an increase in absorption is achieved through plasmonic coupling of a nearby Au thin layer directly or through a spacer to the WS2 monolayer. The optical properties of the designed structures are investigated by the transfer matrix method in the visible wavelength region. In the structure consisting of a WS2 monolayer with Au and spacer layers, the absorption at 619 nm was increased to 61%. Sharp optical absorption as high as 40% for a large range of incidence angles in both polarizations was retained. Our study provides useful information for the design of WS2 monolayers in photonic devices for practical applications.

Ensiyeh Mohebbi

Papers

Increasing optical absorption in one-dimensional photonic crystals including MoS2 monolayer for photovoltaics applications

Broadband and high absorption in Fibonacci photonic crystal including MoS2 monolayer in the visible range

Nearly perfect and broadband optical absorption by TMDCs in cover/TMDC/spacer/Au/substrate multilayers

Approaching the nearly perfect and wavelength-adjustable absorption of MoS2 monolayer using defective quasi photonic crystals

Enhancement of light absorption in a WS2 monolayer using spacer and Au layers