All-optical high-contrast femtosecond switching using nonlinearity from an epsilon-near-zero effect in plasmonic metamaterials.
Opt Lett
; 49(9): 2397-2400, 2024 May 01.
Article
em En
| MEDLINE
| ID: mdl-38691728
ABSTRACT
Metamaterials opened a new realm to control light-matter interactions at sub-wavelength scale by engineering meta-atoms. Recently, the integration of several emerging nonlinear materials with metamaterial structures enables ultra-fast all-optical switching at the nanoscale and thus brings enormous possibilities to realize next-generation optical communication systems. This Letter presents a novel, to the best of our knowledge, design of plasmonic metamaterials for high-contrast femtosecond all-optical switching. We leverage magnetic plasmon (MP) resonance combined with the nonlinear effects of an epsilon-near-zero (ENZ)-material. The proposed design comprises a periodic array of two closely spaced Au-nanogratings deposited on an optically thick Au-substrate to excite MP-resonance. To enable a dynamically tunable resonance, the nanogrooves in meta-atoms are filled with an ENZ-material, cadmium-oxide (CdO). The intraband transition-induced optical nonlinearities in the ENZ-medium are studied using a two-temperature model. The MP-resonance ensures strong light-matter interactions enabling enhancement of the nonlinearities of the proposed structure. We observe that the pump-induced refractive index change in the CdO layer causes a redshift of the MP-resonance dip wavelength in the reflectance spectrum, leading to a high modulation depth of 0.83 at 1.55â
µm. With an ultra-fast response time of 776â
fs while maintaining a low pump-fluence of 75â
µJ/cm2, the proposed metamaterial could help in realizing switches for next-generation optical computation systems.
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MEDLINE
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En
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Opt Lett
Ano de publicação:
2024
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Article