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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

Dependences of the reflectance (a) and transmittance (b) on the incident angle at the different Fermi-level of graphene; (c) Dependences of the resonant angle and FWHM on the Fermi-level of graphene. Where λ=300um, np=ns=4, n1=n2=1.5, d1 = d2 = 30 um.
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f2: Dependences of the reflectance (a) and transmittance (b) on the incident angle at the different Fermi-level of graphene; (c) Dependences of the resonant angle and FWHM on the Fermi-level of graphene. Where λ=300um, np=ns=4, n1=n2=1.5, d1 = d2 = 30 um.

Mentions: The excitation of SPPs with the monolayer graphene in the modified Kretschmann-Raether configuration is demonstrated with the angular reflection and transmission spectra in Fig. 2(a,b), respectively, which are calculated by the modified transfer matrix method35 at the very low incident field. Here the incident wave with free space wavelength of λ = 300 um (f = 1THz) is considered, and the dielectrics 1 and 2 are assumed to be same dielectric constants and thicknesses, n1 = n2 = 1.5, d1 = d2 = 30 um. The Fermi-level is increased from 0.18 eV to 0.45 eV. It is novel that two resonant dips are clearly resolved in each Fermi-level. The first dip originates from the Brewster angle, which is insensitive to the varying of the Fermi-level of graphene. However, the second reflectance dip at the larger angle is very sensitive to the Fermi-level of graphene, which stems from SPPs of graphene. If the graphene is not considered, the second reflectance dip is disappearing immediately.


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

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

Dependences of the reflectance (a) and transmittance (b) on the incident angle at the different Fermi-level of graphene; (c) Dependences of the resonant angle and FWHM on the Fermi-level of graphene. Where λ=300um, np=ns=4, n1=n2=1.5, d1 = d2 = 30 um.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Dependences of the reflectance (a) and transmittance (b) on the incident angle at the different Fermi-level of graphene; (c) Dependences of the resonant angle and FWHM on the Fermi-level of graphene. Where λ=300um, np=ns=4, n1=n2=1.5, d1 = d2 = 30 um.
Mentions: The excitation of SPPs with the monolayer graphene in the modified Kretschmann-Raether configuration is demonstrated with the angular reflection and transmission spectra in Fig. 2(a,b), respectively, which are calculated by the modified transfer matrix method35 at the very low incident field. Here the incident wave with free space wavelength of λ = 300 um (f = 1THz) is considered, and the dielectrics 1 and 2 are assumed to be same dielectric constants and thicknesses, n1 = n2 = 1.5, d1 = d2 = 30 um. The Fermi-level is increased from 0.18 eV to 0.45 eV. It is novel that two resonant dips are clearly resolved in each Fermi-level. The first dip originates from the Brewster angle, which is insensitive to the varying of the Fermi-level of graphene. However, the second reflectance dip at the larger angle is very sensitive to the Fermi-level of graphene, which stems from SPPs of graphene. If the graphene is not considered, the second reflectance dip is disappearing immediately.

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