High Reflection from a One-Dimensional Array of Graphene Nanoribbons

Abstract

We show that up to 90% reflectivity can be achieved by using guided plasmonic resonances in a one-dimensional periodic array of plasmonic nanoribbon. In general, to achieve strong reflection from a guided resonance system requires one to operate in the strongly over-coupled regime where the radiative decay rate dominates over the intrinsic loss rate of the resonances. Using an argument similar to what has been previous used to derive the Chu-Harrington limit for antennas, we show theoretically that there is no intrinsic limit for the radiative decay rate even when the system has an atomic scale thickness, in contrast to the existence of such limits on antennas. We also show that the current distribution due to plasmonic resonance can be designed to achieve very high external radiative rate. Our results show that high reflectivity can be achieved in an atomically-thin graphene layer, pointing to a new opportunity for creating atomically-thin optical devices.Recently there has been significant interest in achieving strong reflection from atomically thin materials, with potential applications in high efficiency optical modulators 1 and for achieving large optomechanical interactions. 2 For this purpose, it is essential to create and utilize various kinds of optical resonances in these materials. For example, it has been recently demonstrated that at low temperature, monolayer MoSe 2 can achieve high reflection of incident light due to its excitonic resonance. 1,3 arXiv:1812.04768v1 [physics.optics]

Atomic-Scale Control of Coherent Thermal Radiation

“…The fact that the atomic layer is in the undercoupling condition makes it possible to enhance the emissivity by enhancing γ r . In the Supporting Information, we show one way of enhancing γ r by bringing the ribbons closer following the method discussed in ref . In doing so, we indeed can observe increases in the peak emissivity.…”

Low-temperature annihilation rate for quasilocalized excitons in monolayer MoS2

“…The final step in the remaining process of obtaining the exciton-exciton annihilation rate is to substitute numerical values into the matrix elements and coefficients in Eq. (28). The matrix element f s|d|ν , corresponding to the annihilation of an exciton at the ground state |ν , was previously determined (via decomposition into the band basis [18]) as proportional to the square root of the localization region area A:…”

“…One important topic of research involves the calculation of the excitonic decay rates through various channels, which play an essential role in determining the dynamic optical response of a monolayer TMD near the exciton resonance. To this end, recent theoretical and phenomenological studies have derived the radiative loss rate for excitons in MoS 2 [18,25] and for other TMDs [26,27], as well as for other low-dimensional systems such as plasmons in graphene nanoribbons [28]. In addition, the nonradiative decay rate due to exciton-phonon scattering has been numerically and phenomenologically derived as a function of temperature for WS 2 and MoSe 2 [27].…”

Phonon Polaritons Assisted Extraordinary Transmission in α-MoO-Silver Grating and Its Application in Switching

“…Momentum matching is achieved by patterning of graphene into nanoribbons to excite plasmonic resonance. These plasmonic resonances allows graphene NRs to act as reflective filters, that screens incoming light and, thus, forms the basis of transmission modulation [45]. This response can be tuned by varying Fermi potential of graphene over a broad wavelength range without changing structural parameters.…”

“…Graphene nanoribbons behave as a tunable reflective modulator, which in turn modifies the output transmission of the EOT structure. Since, graphene's conductivity also depends on the mobility of electrons, and thus follows it linearly, we consider the mobility to be 50 m 2 /(V.s) to obtain large modulation depth [45]. The transmission can now reach a minimum of 0.01% for E F = 0.66 eV.…”