Fano resonances in photonics

Лимонов, М. Ф.; Rybin, Mikhail V.; Poddubny, Alexander N.; Kivshar, Yuri S.

doi:10.1038/nphoton.2017.142

Cited by 1,575 publications

(1,095 citation statements)

References 114 publications

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“…[32,33] In order for this effect to occur, a narrow vibration needs to interact with an energetically broad process that coincides energetically. The resulting Fano profile has the form of (…”

Section: Resultsmentioning

confidence: 99%

Revealing Trap States in Lead Sulphide Colloidal Quantum Dots by Photoinduced Absorption Spectroscopy

Kahmann

Sytnyk

Schrenker

et al. 2017

Adv Elect Materials

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highly attractive for applications in the field of (opto-)electronics-mostly due to the feasible processing from solution and the tunability of their bandgap energy. Lead sulphide (PbS), in particular, attracts considerable interest due to its narrow bulk bandgap of 0.41 eV and the subsequent possibility to harness infrared photons in detectors and solar cells [1][2][3][4] or emit infrared light. [5][6][7] As-synthesized CQDs are commonly covered with long, electrically insulating surface ligands that need to be exchanged in order to promote electrical conduction. This exchange improves the charge carrier mobility, but can simultaneously affect the quantum dot (QD) density of states (DOS) and may introduce in-gap states (IGS). [8] In most cases, IGS are considered as trap states. The high surface to volume ratio renders the CQDs vulnerable to surface-related defects, which might be caused by incomplete surface passivation, surface oxidation, or interfacial states caused by the attachment of exchanged ligands. Such defect states were observed for PbS before by various techniques. Reported were especially a state 0.2 eV above the valence level of 1,2-ethanedithiol or 1,3-mercaptopropionic acid (EDT, MPA) capped CQDs via Kelvin probe force microscopy (KPFM) and scanning tunneling spectroscopy (STS), [9][10][11][12] Additionally, a quasimetallic midgap band ≈0.4 eV below the conduction

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Section: Resultsmentioning

confidence: 99%

Revealing Trap States in Lead Sulphide Colloidal Quantum Dots by Photoinduced Absorption Spectroscopy

Kahmann

Sytnyk

Schrenker

et al. 2017

Adv Elect Materials

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“…The resonance phenomena in photonics allow for strong localization of electromagnetic waves that is essential for numerous applications, [1][2][3][4][5][6][7] such as narrowband filtering, [8] outof-plane wave coupling, [9] chemical and biological sensing, [10] Adv. Optical…”

Section: Terahertz Guided-mode Resonancementioning

confidence: 99%

“…Figure 1c shows the dispersion of a thin film slab waveguide, where the light line is defined by the dispersion relation k k n c ω = | | , which relates the wavevector (k), angular frequency (ω), speed of light in vacuum (c), and refractive index of waveguide material (n). In the vicinity of Γ point (θ = 0°), rigorous calculations account for the interaction of these resonance modes, which show either anticrossing behavior indicating a strong coupling regime, [7,37] or cross-over behavior implying a weak coupling regime, [7,37] as highlighted by the blue and red dispersion curves in Figure 1e, respectively. In the case of patterned silicon layer, the waveguiding criteria of the effective slab waveguide can be expressed as k c n ω θ = sin( ) g , where n g is the average refractive index of the effective slab waveguide and θ is the angle of incidence at the interface of slab waveguide and top cladding (refractive index of n c ).…”

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confidence: 99%

Guided‐Mode Resonances in All‐Dielectric Terahertz Metasurfaces

Han

Rybin

Pitchappa

et al. 2019

Advanced Optical Materials

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The important parameters that describe a resonance feature are its intensity and spectral linewidth. For most practical applications, resonances with strong intensity and narrow linewidth are desirable. Higher resonance intensity provides better signal to noise ratio, while narrower linewidth signifies larger field confinement. However, most of the resonances are constrained by the trade-off between resonance intensity and linewidth. [20] This limits the possibility of independent tailoring of resonance features at will. On the contrary, guided mode resonance (GMR) can provide arbitrary resonance intensity and linewidth through geometrical design and selection of materials. [8] Due to this versatile nature of GMRs, they have found wide range of applications, including extremely high-Q filters, ultrabroadband reflectors, wavelength selective polarizers, and beam splitters. [8,[21][22][23][24][25][26][27][28][29][30][31] The GMR filter primarily comprises of a diffractive grating and an in-plane waveguide. The grating diffracts the incident light and couples it into the waveguide, which propagates as a guided mode. However, this guided mode is designed to be leaky, which then interferes with the free-space propagating electromagnetic wave to give rise to the GMRs. Through the selection of material, grating design, dielectric layer thickness, and angle of incidence, GMRs can provide a wide range of spectral features. Currently, the exploration of GMRs is limited to optical and radio frequency regions of the electromagnetic spectrum. However, terahertz (THz) technologies are attracting a lot of attention to cater to the challenges of meeting ever-increasing demand for highspeed wireless communications. [32] THz GMR devices could play a crucial role in communication applications due to its capability for constructing high-Q filters, polarization selective beam splitters, differentiators, integrators, and wavelength division (de)multiplexers. [8] Earlier reports on THz GMRs were realized through 1D grating elements on quartz substrate [33] and periodic metallic patterns on cyclo-olefin substrates. [34] Here, we experimentally demonstrate silicon-based all-dielectric metasurfaces that support GMRs at THz frequencies.The 2D metasurface, building block with periodic array of subwavelength silicon microstructures, simultaneously acts as the diffraction grating as well as the slab waveguide and hence enables the observation of GMRs. At oblique incidence, two frequency detuned GMRs are observed, which arises from two Coupling of diffracted waves in gratings with the waveguide modes gives rise to the guided mode resonances (GMRs). The GMRs provide designer linewidth and resonance intensity amidst a broad background, and thus have been widely used for numerous applications in visible and infrared spectral regions. Here, terahertz GMRs are demonstrated in low-loss, all-dielectric metasurfaces, which are periodic square lattices of silicon cuboids on quartz substrates. The silicon cuboid lattice simultaneously acts as a diffract...

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“…Mode splitting induced by coherent optical mode interference in coupled resonant cavities is a key phenomenon in photonic resonators that can lead to powerful and versatile filtering functions such as optical analogous to electromagnetically induced-transparency (EIT), Fano resonances, Autler-Townes splitting, and dark states. [3][4][5] It is similar in principle to atomic resonance splitting caused by quantum interference between excitation pathways in multi-level atomic systems. 6 One great advantage of this effect is that it can break the dependence between the quality factor, free spectral range (FSR), and physical cavity length.…”

Section: Introductionmentioning

confidence: 99%

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

et al. 2018

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We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

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Fano resonances in photonics

Cited by 1,575 publications

References 114 publications

Revealing Trap States in Lead Sulphide Colloidal Quantum Dots by Photoinduced Absorption Spectroscopy

Revealing Trap States in Lead Sulphide Colloidal Quantum Dots by Photoinduced Absorption Spectroscopy

Guided‐Mode Resonances in All‐Dielectric Terahertz Metasurfaces

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

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