Active switching and tuning of sharp Fano resonances in the mid-infrared spectral region

Lee, Eunsongyi; Seo, In Cheol; Lim, Sung Chan; Jeong, Hoon Yeub; Jun, Young Chul

doi:10.1364/oe.24.025684

Cited by 21 publications

(12 citation statements)

References 45 publications

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“…Consequently, the FoM reaches a maximum value at 0.6 D 0 . Such opposite trends of the Q factor and the resonance intensity have been observed recently in other Fano resonant systems 17 , 18 , 23 , 24 and were ascribed to the degree of asymmetry in the resonant structure. In our hollow structures, the structural asymmetry between the two cylinder particles decreases as the hole size increases i.e .…”

Section: Resultssupporting

confidence: 68%

Theoretical investigations on microwave Fano resonances in 3D-printable hollow dielectric resonators

Lee

Seo

Jeong

et al. 2017

Sci Rep

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High-index dielectric structures have recently been studied intensively for Mie resonances at optical frequencies. These dielectric structures can enable extreme light manipulation, similar to that which has been achieved with plasmonic nanostructures. In the microwave region, dielectric resonators and metamaterials can be fabricated directly using 3D printing, which is advantageous for fabricating structurally complicated 3D geometries. It is therefore especially suitable for the fabrication of subwavelength structures. Here we report theoretical investigations on microwave Fano resonances in 3D-printable dielectric materials and structures. In particular, we propose and analyse 3D-printable, hollow, dielectric resonators with relatively low refractive indices, which exhibit sharp Fano resonances. We can control the interaction between bright and dark modes in a coupled dielectric particle pair by adjusting the inner-hole size, and thus we can increase the radiative Q factors further. We also find that Fano resonances in these hollow dielectric resonators are very sensitive to an index change in the surrounding medium, which could be useful for long-distance environmental sensing. New possibilities and opportunities are opening up with the rapid development of 3D-printing technologies. Our findings and the detailed investigations reported here can provide useful guidelines for future photonic devices based on 3D-printable materials and structures.

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Section: Resultssupporting

confidence: 68%

Theoretical investigations on microwave Fano resonances in 3D-printable hollow dielectric resonators

Lee

Seo

Jeong

et al. 2017

Sci Rep

Self Cite

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“…Manipulating the free carrier density of GaAs via the optical pumping results in a variation of GaAs permittivity and its conductivity. The permittivity of the GaAs at THz frequencies is calculated by the classic Drude model through the following expression [31,32].…”

Section: Theory and Structure Designmentioning

confidence: 99%

Design and analysis of a high-performance terahertz photoconductive modulator enhanced by photonic crystal cavity

2022

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We propose and design a high-speed and high-performance optically controlled terahertz (THz) intensity modulator based on the free carrier modulation of a GaAs semiconductor. The device comprises a photonic crystal cavity-waveguide coupling structure for operation in the THz region. This modulator benefits from the strong interaction between the THz wave and the photoconductive substance to obtain a deep modulation with GHz speed, even with a low external optical power. The finite element method was used to calculate the most important properties of the modulator, such as the modulation depth, insertion loss, and modulation rate. The proposed modulator also demonstrated external optical powerdependent characteristics. The results indicate that the THz intensity can be modulated at a switching frequency of 1 GHz with high modulation depths of 83% and 90.3% under the continuous wave laser pumping of 50 W/cm 2 and 80 W/cm 2 respectively. In addition, this modulator exhibits efficient performance under the same pumping power with a switching frequency of up to 3 GHz. The device exhibited higher modulation depths with higher laser power intensities. The outstanding properties of the proposed structure are promising for the development of modulators and switches in THz communication systems.

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“…These tightly confined fields could be switched with extremely low-threshold stimulus in the form of electrical or optical stimulus that could drive an active material out of equilibrium in the capacitive gaps. [25][26][27][28][29][30][31] For example, an electrically controlled Fano resonance was observed at NIR wavelengths using a graphene-nanoantenna hybrid structure. [21] Early studies on tuning the Fano resonance mainly rely on changing the asymmetry parameter or the coupling distance within the unit cell of the Fano metasurface.…”

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confidence: 99%

Active Control of Asymmetric Fano Resonances with Graphene–Silicon‐Integrated Terahertz Metamaterials

Gupta

Zhang

et al. 2020

Adv Materials Technologies

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such as invisibility cloaking, super focusing, beam steering, sensing, modulating, polarization control, lasing, and nonlinear optics. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] One of the potential application of a metasurface platform is to enable strong light-matter coupling, where high-quality (Q) factor resonances are absolutely essential. [16,17] Fano resonances support narrow linewidths with large Q factor values. [18][19][20] The large Q factor of Fano resonant metasurfaces is derived from the enhanced electric field in the subwavelength capacitive gaps of the symmetry-broken resonators. These tightly confined fields could be switched with extremely low-threshold stimulus in the form of electrical or optical stimulus that could drive an active material out of equilibrium in the capacitive gaps. Such prospect of active switching of resonantly confined fields in metasurfaces could be significant for future applications based on light-matter interaction. [21] Early studies on tuning the Fano resonance mainly rely on changing the asymmetry parameter or the coupling distance within the unit cell of the Fano metasurface. [22][23][24] Although significant modulation of the Fano resonances was achieved, they work in passive mode. Therefore, it is important to find alternative design routes for active control of metasurfaces. One possible route is to change the conductivity of the Fano structure, so as to alter the resonance loss. Till date, there have been quite a few reports where the Fano structures were integrated with dynamic materials under external stimulus. [25][26][27][28][29][30][31] For example, an electrically controlled Fano resonance was observed at NIR wavelengths using a graphene-nanoantenna hybrid structure. [30] In addition, by implanting structured silicon patch arrays into asymmetric metallic split-ring resonators, active photoswitching of sharp Fano resonances was realized in the terahertz regime. [31] However, most of them are realized by applying single control stimulus. Active tuning approaches of Fano resonances could be further optimized by incorporating dual control, where a combination of voltage and optical pump could be simultaneously applied. Such dual control would diversify the practical implementation of these devices, as it could bridge the gap between optics and electronics. Graphenesilicon heterostructure could be one such potential system in which Fermi level of graphene responds to applied voltage, [32][33][34][35] while carrier concentration in hybrid system is controlled by Planar metamaterials are extensively studied in recent years due to their potential applications in design of flat optical components, ultrasensitive sensors, lasing spasers, and nonlinear devices. Recent studies have reported dynamic control of photoactive material-based metamaterials through optical excitation. However, most of the previous demonstrations rely on single stimulus control and typically require large fluence and ultrafast pulses of light. Here, graphene is integrated with Fano re...

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Active switching and tuning of sharp Fano resonances in the mid-infrared spectral region

Cited by 21 publications

References 45 publications

Theoretical investigations on microwave Fano resonances in 3D-printable hollow dielectric resonators

Theoretical investigations on microwave Fano resonances in 3D-printable hollow dielectric resonators

Design and analysis of a high-performance terahertz photoconductive modulator enhanced by photonic crystal cavity

Active Control of Asymmetric Fano Resonances with Graphene–Silicon‐Integrated Terahertz Metamaterials

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