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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

(a) Dependence of transmittance on the incident angle at the different relaxation time τ of graphene; Dependences of transmitted electric field and transmittance on the incident electric field in (b) for τ = 1 ps and (c) for 0.5 ps, respectively. Where λ = 100 um, np = ns = 4, n1 = n2 = 1.5, d = 5um, EF = 1.0 eV, and θi = 62° in (b), and θi = 70° in (c), respectively.
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f7: (a) Dependence of transmittance on the incident angle at the different relaxation time τ of graphene; Dependences of transmitted electric field and transmittance on the incident electric field in (b) for τ = 1 ps and (c) for 0.5 ps, respectively. Where λ = 100 um, np = ns = 4, n1 = n2 = 1.5, d = 5um, EF = 1.0 eV, and θi = 62° in (b), and θi = 70° in (c), respectively.

Mentions: We further assume that the nonlinear response is not influenced by the introduction of the relaxation time τ In Fig. 7(a), we illustrate the dependence of transmittance on the incident angle at the different relaxation time τ of graphene. It is seen clearly that the transmittance is decreased distinctly. Although the relaxation time τ has great influence on the SPPs and hysterical effect, the optical bistability can still exist at the acceptable threshold value of the incident electric field as shown in Fig. 7(b,c). With the introduction of the relaxation time τ, the absorption increases and the transmittance decreases therefore leading to higher energy requirements to excite the optical bistability. Hence as the relaxation time τ decreases, both the switching-up and switching-down threshold values shifts to higher incident electric fields. But these electric fields are still in the range of the actual electric field experimentally as discussed above.


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

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

(a) Dependence of transmittance on the incident angle at the different relaxation time τ of graphene; Dependences of transmitted electric field and transmittance on the incident electric field in (b) for τ = 1 ps and (c) for 0.5 ps, respectively. Where λ = 100 um, np = ns = 4, n1 = n2 = 1.5, d = 5um, EF = 1.0 eV, and θi = 62° in (b), and θi = 70° in (c), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f7: (a) Dependence of transmittance on the incident angle at the different relaxation time τ of graphene; Dependences of transmitted electric field and transmittance on the incident electric field in (b) for τ = 1 ps and (c) for 0.5 ps, respectively. Where λ = 100 um, np = ns = 4, n1 = n2 = 1.5, d = 5um, EF = 1.0 eV, and θi = 62° in (b), and θi = 70° in (c), respectively.
Mentions: We further assume that the nonlinear response is not influenced by the introduction of the relaxation time τ In Fig. 7(a), we illustrate the dependence of transmittance on the incident angle at the different relaxation time τ of graphene. It is seen clearly that the transmittance is decreased distinctly. Although the relaxation time τ has great influence on the SPPs and hysterical effect, the optical bistability can still exist at the acceptable threshold value of the incident electric field as shown in Fig. 7(b,c). With the introduction of the relaxation time τ, the absorption increases and the transmittance decreases therefore leading to higher energy requirements to excite the optical bistability. Hence as the relaxation time τ decreases, both the switching-up and switching-down threshold values shifts to higher incident electric fields. But these electric fields are still in the range of the actual electric field experimentally as discussed above.

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