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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

Dependence of transmitted electric field on the incident electric field for EF = 0.18 eV and 0.25 eV, respectively, where λ = 300 um, np = ns = 4, n1 = n2 = 1.5. EF = 0.18eV, d = 30 um, θi = 80° for (a) and EF = 0.25 eV, d = 60 um, θi = 48.2° for (b).
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f5: Dependence of transmitted electric field on the incident electric field for EF = 0.18 eV and 0.25 eV, respectively, where λ = 300 um, np = ns = 4, n1 = n2 = 1.5. EF = 0.18eV, d = 30 um, θi = 80° for (a) and EF = 0.25 eV, d = 60 um, θi = 48.2° for (b).

Mentions: Here, we have chosen two cases as the examples. The results have been illustrated in Fig. 5(a,b). For EF = 0.18 eV and d = 30 um, the resonant angle in the low electric field is θR = 78.4° and FWHM of the resonance is Δθ = 0.57°, then we set the incident angle θi = 80°. For EF = 0.25 eV and d = 60 um, the resonant angle in the low electric field is θR = 47.8° and FWHM of the resonance is Δθ = 0.09°, then we set the incident angle θi = 48.2°. The switching-up and switching-down threshold values are 4.16 × 104 W/m2 and 2.55 × 105 W/m2 for EF = 0.18 eV, respectively; and the corresponding switching-up and switching-down threshold values are 2.38 × 104 W/m2 and 2.31 × 105 W/m2 for EF = 0.25 eV, respectively. These threshold values have been lowered by two orders of magnitude compared to the values in Fig. 4. As a matter of fact, these threshold values can be further reduced by decreasing the Fermi-level and increasing the thickness d at the same time. And that the Fermi-level can be tuned by controlling the bias voltage applied on the graphene sheet, hence which provides a new way to realize the tunable optical bistable devices for future THz optical communication technology.


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

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

Dependence of transmitted electric field on the incident electric field for EF = 0.18 eV and 0.25 eV, respectively, where λ = 300 um, np = ns = 4, n1 = n2 = 1.5. EF = 0.18eV, d = 30 um, θi = 80° for (a) and EF = 0.25 eV, d = 60 um, θi = 48.2° for (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Dependence of transmitted electric field on the incident electric field for EF = 0.18 eV and 0.25 eV, respectively, where λ = 300 um, np = ns = 4, n1 = n2 = 1.5. EF = 0.18eV, d = 30 um, θi = 80° for (a) and EF = 0.25 eV, d = 60 um, θi = 48.2° for (b).
Mentions: Here, we have chosen two cases as the examples. The results have been illustrated in Fig. 5(a,b). For EF = 0.18 eV and d = 30 um, the resonant angle in the low electric field is θR = 78.4° and FWHM of the resonance is Δθ = 0.57°, then we set the incident angle θi = 80°. For EF = 0.25 eV and d = 60 um, the resonant angle in the low electric field is θR = 47.8° and FWHM of the resonance is Δθ = 0.09°, then we set the incident angle θi = 48.2°. The switching-up and switching-down threshold values are 4.16 × 104 W/m2 and 2.55 × 105 W/m2 for EF = 0.18 eV, respectively; and the corresponding switching-up and switching-down threshold values are 2.38 × 104 W/m2 and 2.31 × 105 W/m2 for EF = 0.25 eV, respectively. These threshold values have been lowered by two orders of magnitude compared to the values in Fig. 4. As a matter of fact, these threshold values can be further reduced by decreasing the Fermi-level and increasing the thickness d at the same time. And that the Fermi-level can be tuned by controlling the bias voltage applied on the graphene sheet, hence which provides a new way to realize the tunable optical bistable devices for future THz optical communication technology.

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