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Low threshold optical bistability at terahertz frequencies with graphene surface plasmons.

Dai X, Jiang L, Xiang Y - Sci Rep (2015)

Bottom Line: It is found that the switching-up and switching-down intensities required to observe the optical bistable behavior are lowered markedly due to the excitation of the graphene surface plasmons, thus making this configuration a prime candidate for experimental investigation at the terahertz range.And the switching threshold value can be further reduced by decreasing the Fermi-level or increasing the thickness of sandwich structure, hence providing a new way for realizing tunable optical bistable devices.Finally, the optical bistability at higher terahertz frequency and the influence of relaxation time under the actual experimental condition on Fermi-level are discussed.

View Article: PubMed Central - PubMed

Affiliation: SZU-NUS Collaborative Innovation Center for Optoelectronic Science &Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.

ABSTRACT
We propose a modified Kretschmann-Raether configuration to realize the low threshold optical bistable devices at the terahertz frequencies. The metal layer is replaced by the dielectric sandwich structure with the insertion of graphene, and this configuration can support TM-polarization surface electromagnetic wave. The surface plasmon resonance is strongly dependent on the Fermi-level of graphene and the thickness of the sandwich structure. It is found that the switching-up and switching-down intensities required to observe the optical bistable behavior are lowered markedly due to the excitation of the graphene surface plasmons, thus making this configuration a prime candidate for experimental investigation at the terahertz range. And the switching threshold value can be further reduced by decreasing the Fermi-level or increasing the thickness of sandwich structure, hence providing a new way for realizing tunable optical bistable devices. Finally, the optical bistability at higher terahertz frequency and the influence of relaxation time under the actual experimental condition on Fermi-level are discussed.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of a modified Kretschmann-Raether configuration, where the metal layer in Kretschmann-Raether configuration is replaced by the dielectric sandwiched structure with the insertion of graphene sheet.A plane wave of amplitude Hi(Ei) is incident on the sandwiched structure with incident angle θi, giving rise to a reflected and a transmitted wave with amplitude Hr(Er) and Ht(Et), respectively. The surface plasmon wave is excited at the interface of the two dielectric with graphene sheet.
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f1: Schematic diagram of a modified Kretschmann-Raether configuration, where the metal layer in Kretschmann-Raether configuration is replaced by the dielectric sandwiched structure with the insertion of graphene sheet.A plane wave of amplitude Hi(Ei) is incident on the sandwiched structure with incident angle θi, giving rise to a reflected and a transmitted wave with amplitude Hr(Er) and Ht(Et), respectively. The surface plasmon wave is excited at the interface of the two dielectric with graphene sheet.

Mentions: Surface plasmons in graphene have been extensively studied both theoretically and experimentally in recent years89. It is well known that the graphene can support p-polarized surface plasmon polariton (SPP) or transverse magnetic (TM) surface wave at the interface of the two dielectrics with the graphene. However, it requires that the graphene should have a positive imaginary part of the surface conductivity. Moreover, it also can support TE-polarized surface electromagnetic wave if the imaginary part of the surface conductivity is negative, however, which is not supporting for an ordinary metal. According to the surface conductivity of graphene in THz frequencies as indicated in Eq. (1), we know that the imaginary part of the linear graphene surface conductivity at the low THz frequency is always positive which leads to the TM surface plasmon wave in the limit , as shown in Fig. 1.


Low threshold optical bistability at terahertz frequencies with graphene surface plasmons.

Dai X, Jiang L, Xiang Y - Sci Rep (2015)

Schematic diagram of a modified Kretschmann-Raether configuration, where the metal layer in Kretschmann-Raether configuration is replaced by the dielectric sandwiched structure with the insertion of graphene sheet.A plane wave of amplitude Hi(Ei) is incident on the sandwiched structure with incident angle θi, giving rise to a reflected and a transmitted wave with amplitude Hr(Er) and Ht(Et), respectively. The surface plasmon wave is excited at the interface of the two dielectric with graphene sheet.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508658&req=5

f1: Schematic diagram of a modified Kretschmann-Raether configuration, where the metal layer in Kretschmann-Raether configuration is replaced by the dielectric sandwiched structure with the insertion of graphene sheet.A plane wave of amplitude Hi(Ei) is incident on the sandwiched structure with incident angle θi, giving rise to a reflected and a transmitted wave with amplitude Hr(Er) and Ht(Et), respectively. The surface plasmon wave is excited at the interface of the two dielectric with graphene sheet.
Mentions: Surface plasmons in graphene have been extensively studied both theoretically and experimentally in recent years89. It is well known that the graphene can support p-polarized surface plasmon polariton (SPP) or transverse magnetic (TM) surface wave at the interface of the two dielectrics with the graphene. However, it requires that the graphene should have a positive imaginary part of the surface conductivity. Moreover, it also can support TE-polarized surface electromagnetic wave if the imaginary part of the surface conductivity is negative, however, which is not supporting for an ordinary metal. According to the surface conductivity of graphene in THz frequencies as indicated in Eq. (1), we know that the imaginary part of the linear graphene surface conductivity at the low THz frequency is always positive which leads to the TM surface plasmon wave in the limit , as shown in Fig. 1.

Bottom Line: It is found that the switching-up and switching-down intensities required to observe the optical bistable behavior are lowered markedly due to the excitation of the graphene surface plasmons, thus making this configuration a prime candidate for experimental investigation at the terahertz range.And the switching threshold value can be further reduced by decreasing the Fermi-level or increasing the thickness of sandwich structure, hence providing a new way for realizing tunable optical bistable devices.Finally, the optical bistability at higher terahertz frequency and the influence of relaxation time under the actual experimental condition on Fermi-level are discussed.

View Article: PubMed Central - PubMed

Affiliation: SZU-NUS Collaborative Innovation Center for Optoelectronic Science &Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.

ABSTRACT
We propose a modified Kretschmann-Raether configuration to realize the low threshold optical bistable devices at the terahertz frequencies. The metal layer is replaced by the dielectric sandwich structure with the insertion of graphene, and this configuration can support TM-polarization surface electromagnetic wave. The surface plasmon resonance is strongly dependent on the Fermi-level of graphene and the thickness of the sandwich structure. It is found that the switching-up and switching-down intensities required to observe the optical bistable behavior are lowered markedly due to the excitation of the graphene surface plasmons, thus making this configuration a prime candidate for experimental investigation at the terahertz range. And the switching threshold value can be further reduced by decreasing the Fermi-level or increasing the thickness of sandwich structure, hence providing a new way for realizing tunable optical bistable devices. Finally, the optical bistability at higher terahertz frequency and the influence of relaxation time under the actual experimental condition on Fermi-level are discussed.

No MeSH data available.


Related in: MedlinePlus