Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAmplification of surface plasmons in graphene-black phosphorus injection laser heterostructures
88
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We propose and evaluate the heterostructure based on the graphene-layer (GL) with the lateral electron injection from the side contacts and the hole vertical injection via the black phosphorus layer (PL) (p$^+$PL-PL-GL heterostructure). Due to a relatively small energy of the holes injected from the PL into the GL (about 100 meV, smaller than the energy of optical phonons in the GL which is about 200 meV), the hole injection can effectively cool down the two-dimensional electron-hole plasma in the GL. This simplifies the realization of the interband population inversion and the achievement of the negative dynamic conductivity in the terahertz (THz) frequency range enabling the amplification of the surface plasmon modes. The later can lead to the plasmon lasing. The conversion of the plasmons into the output radiation can be used for a new types of the THz sources.
rate research
Read More
Recently, it was demonstrated that a graphene/dielectric/metal configuration can support acoustic plasmons, which exhibit extreme plasmon confinement an order of magnitude higher than that of conventional graphene plasmons. Here, we investigate acoustic plasmons supported in a monolayer and multilayers of black phosphorus (BP) placed just a few nanometers above a conducting plate. In the presence of a conducting plate, the acoustic plasmon dispersion for the armchair direction is found to exhibit the characteristic linear scaling in the mid- and far-infrared regime while it largely deviates from that in the long wavelength limit and near-infrared regime. For the zigzag direction, such scaling behavior is not evident due to relatively tighter plasmon confinement. Further, we demonstrate a new design for an acoustic plasmon resonator that exhibits higher plasmon confinement and resonance efficiency than BP ribbon resonators in the mid-infrared and longer wavelength regime. Theoretical framework and new resonator design studied here provide a practical route toward the experimental verification of the acoustic plasmons in BP and open up the possibility to develop novel plasmonic and optoelectronic devices that can leverage its strong in-plane anisotropy and thickness-dependent band gap.
It is by now well established that high-quality graphene enables a gate-tunable low-loss plasmonic platform for the efficient confinement, enhancement, and manipulation of optical fields spanning a broad range of frequencies, from the mid infrared to the Terahertz domain. While all-electrical detection of graphene plasmons has been demonstrated, electrical plasmon injection (EPI), which is crucial to operate nanoplasmonic devices without the encumbrance of a far-field optical apparatus, remains elusive. In this work, we present a theory of EPI in double-layer graphene, where a vertical tunnel current excites acoustic and optical plasmon modes. We first calculate the power delivered by the applied inter-layer voltage bias into these collective modes. We then show that this system works also as a spectrally-resolved molecular sensor.
We report on nano-infrared (IR) imaging studies of confined plasmon modes inside patterned graphene nanoribbons (GNRs) fabricated with high-quality chemical-vapor-deposited (CVD) graphene on Al2O3 substrates. The confined geometry of these ribbons leads to distinct mode patterns and strong field enhancement, both of which evolve systematically with the ribbon width. In addition, spectroscopic nano-imaging in mid-infrared 850-1450 cm-1 allowed us to evaluate the effect of the substrate phonons on the plasmon damping. Furthermore, we observed edge plasmons: peculiar one-dimensional modes propagating strictly along the edges of our patterned graphene nanostructures.
The possibility of hybridizing collective electronic motion with mid-infrared (mid-IR) light to form surface polaritons has made van der Waals layered materials a versatile platform for extreme light confinement and tailored nanophotonics. Graphene and its heterostructures have attracted particular attention because the absence of an energy gap allows for plasmon polaritons to be continuously tuned. Here, we introduce black phosphorus (BP) as a promising new material in surface polaritonics that features key advantages for ultrafast switching. Unlike graphene, BP is a van der Waals bonded semiconductor, which enables high-contrast interband excitation of electron-hole pairs by ultrashort near-infrared (near-IR) pulses. We design a SiO$_2$/BP/SiO$_2$ heterostructure in which the surface phonon modes of the SiO$_2$ layers hybridize with surface plasmon modes in BP that can be activated by photo-induced interband excitation. Within the Reststrahlen band of SiO$_2$, the hybrid interface polariton assumes surface-phonon-like properties, with a well-defined frequency and momentum and excellent coherence. During the lifetime of the photogenerated electron-hole plasma, coherent polariton waves can be launched by a broadband mid-IR pulse coupled to the tip of a scattering-type scanning near-field optical microscopy (s-SNOM) setup. The scattered radiation allows us to trace the new hybrid mode in time, energy, and space. We find that the surface mode can be activated within ~50 fs and disappears within 5 ps, as the electron-hole pairs in BP recombine. The excellent switching contrast and switching speed, the coherence properties, and the constant wavelength of this transient mode make it a promising candidate for ultrafast nanophotonic devices.
A single-wall carbon nanotube possesses two different types of plasmons specified by the wavenumbers in the azimuthal and axial directions. The azimuthal plasmon that is caused by interband transitions has been studied, while the effect of charge doping is unknown. In this paper, we show that when nanotubes are heavily doped, intraband transitions cause the azimuthal plasmons to appear as a plasmon resonance in the near-infrared region of the absorption spectra, which is absent for light doping due to the screening effect. The axial plasmons that are inherent in the cylindrical waveguide structures of nanotubes, account for the absorption peak of the metallic nanotube observed in the terahertz region. The excitation of axial (azimuthal) plasmons requires a linearly polarized light parallel (perpendicular) to the tubes axis.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
