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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) transmittance (b) on the incident angle at the different thickness d; (c) Dependences of the resonant angle and FWHM of resonant state on the thickness d. Where λ = 300 um, np=ns = 4, n1 = n2 = 1.5, EF = 0.25 eV.
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f3: Dependences of the reflectance (a) transmittance (b) on the incident angle at the different thickness d; (c) Dependences of the resonant angle and FWHM of resonant state on the thickness d. Where λ = 300 um, np=ns = 4, n1 = n2 = 1.5, EF = 0.25 eV.

Mentions: Besides the dependence of the resonant angular spectra on the Fermi-level of graphene, the resonant angular spectra are strongly influenced by the thicknesses of the dielectric slabs 1 and 2, as shown in Fig. 3(a,b). Here we always assume that d1 = d2 = d, and EF is fixed at 0.25 eV. We focus on the second resonant dip, and find that the resonant angle shifts to the smaller angle with the increase of thickness d. Meanwhile, the width of resonant angle becomes very narrow which will benefit the low threshold optical bistability. For d = 15 um, the resonant angle θR = 64.46°, and FWHM of the resonance Δθ = 5.19°; for d = 60 um, the resonant angle θR = 47.87°, and FWHM of the resonance Δθ = 0.09°. Figure 3(c) displays the resonant angle and FWHM of resonance as the function of the continuously variable thickness d.


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) transmittance (b) on the incident angle at the different thickness d; (c) Dependences of the resonant angle and FWHM of resonant state on the thickness d. Where λ = 300 um, np=ns = 4, n1 = n2 = 1.5, EF = 0.25 eV.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Dependences of the reflectance (a) transmittance (b) on the incident angle at the different thickness d; (c) Dependences of the resonant angle and FWHM of resonant state on the thickness d. Where λ = 300 um, np=ns = 4, n1 = n2 = 1.5, EF = 0.25 eV.
Mentions: Besides the dependence of the resonant angular spectra on the Fermi-level of graphene, the resonant angular spectra are strongly influenced by the thicknesses of the dielectric slabs 1 and 2, as shown in Fig. 3(a,b). Here we always assume that d1 = d2 = d, and EF is fixed at 0.25 eV. We focus on the second resonant dip, and find that the resonant angle shifts to the smaller angle with the increase of thickness d. Meanwhile, the width of resonant angle becomes very narrow which will benefit the low threshold optical bistability. For d = 15 um, the resonant angle θR = 64.46°, and FWHM of the resonance Δθ = 5.19°; for d = 60 um, the resonant angle θR = 47.87°, and FWHM of the resonance Δθ = 0.09°. Figure 3(c) displays the resonant angle and FWHM of resonance as the function of the continuously variable thickness d.

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