Anisotropic leaky-like perturbation with subwavelength gratings enables zero crosstalk

Kabir, Md Faiyaz; Mia, Borhan; Ahmed, Ishtiaque; Jaidye, Nafiz; Ahmed, Syed Ijlal; Kim, Sangsik

doi:10.1038/s41377-023-01184-5

Cited by 10 publications

(1 citation statement)

References 49 publications

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“…To overcome this issue, an extreme skin-depth (eskid) waveguide using anisotropic metamaterial cladding has recently been explored in the Si photonics platform to efficiently suppress crosstalk. [3][4][5] Subwavelength grating (SWG) acts as an anisotropic cladding, which can even realize the ideal zero-crosstalk by anisotropic perturbation effect.…”

Section: Introductionmentioning

confidence: 99%

Crosstalk suppression in germanium-on-insulator platform using subwavelength gratings for mid-infrared photonics

Shin,

Lim,

Kim

et al. 2024

Integrated Optics: Devices, Materials, and Technologies XXVIII

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Mid-infrared (MIR) is a promising spectral regime for gas and biochemical sensing since each molecule exhibits a unique vibrational absorption spectrum at this band. While integrated photonics on silicon-on-insulator (SOI) has become a successful platform, it cannot cover a broad MIR range, mainly limited by oxide absorption. Recently, a germanium-on-insulator (GOI) has emerged as a promising integrated photonics platform with broadband transparency covering 2-14 µm wavelengths. Germanium (Ge) and yttrium oxide (Y 2 O 3 ), which exhibit low loss at the MIR regime, are used as a core and box insulator, respectively. However, the prevailing crosstalk issue of integrated photonics becomes more problematic at MIR due to extended evanescent fields with a longer wavelength. To address this issue, we propose using subwavelength gratings (SWGs), which can be effectively represented by homogenized anisotropic metamaterials. We arranged the SWGs in the cladding and formed an extreme skin-depth (eskid) waveguide, whose skin-depth is suppressed for transverse-electric (TE) mode. We then optimized SWG parameters to achieve an exceptional coupling that can completely suppress the crosstalk, i.e., zero crosstalk. Anisotropic dielectric perturbation via SWG metamaterials allowed different field components to compensate for each other, making the overall coupling coefficient zero. We optimized our SWG-based eskid waveguide scheme near 4.2 µm wavelength, where we can directly apply it for CO 2 sensing with its strong absorption. We expect our eskid scheme on the GOI platform to improve the overall performances of MIR photonic devices, especially for MIR molecular sensing applications.

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Section: Introductionmentioning

confidence: 99%

Crosstalk suppression in germanium-on-insulator platform using subwavelength gratings for mid-infrared photonics

Shin,

Lim,

Kim

et al. 2024

Integrated Optics: Devices, Materials, and Technologies XXVIII

Self Cite

View full text Add to dashboard Cite

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Decoupled Dipole Arrays Empowered by Invisible Complex Poles in Epsilon‐Near‐Zero Metamaterials

Zhu,

Liao,

Tang

et al. 2024

Adv Funct Materials

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Evanescent waves, characterized by an exponential decay in propagation, have witnessed significant advancements in far‐field imaging and near‐field sensing applications. However, incoming evanescent waves can excite guided resonance inside a dielectric slab, resulting in a rapid growth of transmission coefficient toward infinity at the pole points. Such evanescent‐wave excited resonance benefits super‐resolution applications yet causes severe crosstalk in highly integrated multi‐channel devices. Here, the invisible complex poles are discovered in the transmission spectra of epsilon‐near‐zero (ENZ) metamaterials and demonstrate the striking suppression of near‐field crosstalk enabled by the anomalous transmission beyond the critical angle. Equipped with an ENZ metamaterial spacer, collinear dipole arrays exhibit 9.2 dB improvement in near‐field isolation among interior dipoles at a distance of less than one wavelength. Experimental measurements show negligible influence on the intrinsic impedance matching and radiation patterns of the dipole antennas. The discovered field divergence effect from the disappearance of real‐valued pole singularity in ENZ metamaterials offers an alternative solution for highly compact arrays in full duplex communication and multiple‐input multiple‐output technology.

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Morphology Engineering Enabled Mid‐Infrared Ultra‐Dense Waveguide Array with Low Crosstalk

Li,

Zhang,

Zhou

et al. 2024

Laser & Photonics Reviews

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The mid‐infrared (MIR) band holds significant promise in various fields, including thermal imaging, spectroscopy sensing, infrared countermeasures, and free‐space communication, due to its distinctive characteristics. Despite substantial efforts that have been dedicated to building on‐chip photonic integrated circuits for MIR, enabling system miniaturization and broadening application scopes, the challenge of crosstalk among closely packed waveguides persists, hampering improvements in integration density and device performance. Here, a morphology engineering approach is proposed to tailor coupling and suppress crosstalk within a densely arranged waveguide array. These results demonstrate that by introducing a periodic Bezier curve to adorn the waveguide trajectory, coherent coupling can be disrupted, isolating each waveguide and minimizing crosstalk in the array. An experimentally demonstrated eight‐channel waveguide array with a half‐wavelength pitch operating at 3.55 µm exhibits crosstalk suppression exceeding −29 dB, representing an 8 dB improvement compared to a sinusoidal trajectory. This methodology, offering precise control of on‐chip light guiding, coupling, and routing, provides a promising perspective for high‐density design in photonic integrated circuits at MIR.

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Anisotropic leaky-like perturbation with subwavelength gratings enables zero crosstalk

Cited by 10 publications

References 49 publications

Crosstalk suppression in germanium-on-insulator platform using subwavelength gratings for mid-infrared photonics

Crosstalk suppression in germanium-on-insulator platform using subwavelength gratings for mid-infrared photonics

Decoupled Dipole Arrays Empowered by Invisible Complex Poles in Epsilon‐Near‐Zero Metamaterials

Morphology Engineering Enabled Mid‐Infrared Ultra‐Dense Waveguide Array with Low Crosstalk

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