The dispersion of a three-way waveguide is engineered to exhibit exceptional modal characteristics. Two coupled waveguides with parity-time (PT) symmetry have been previously demonstrated to exhibit second order excep...
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The dispersion of a three-way waveguide is engineered to exhibit exceptional modal characteristics. Two coupled waveguides with parity-time (PT) symmetry have been previously demonstrated to exhibit second order exceptional points of degeneracy (EPDs). In this work, we introduce and investigate a particular class of EPDs, applicable from radio frequency to optical wavelengths, whereby three coupled waveguides satisfy glide-time (GT) symmetry to exhibit a third order modal degeneracy with a real-valued wave number. GT symmetry involves glide symmetry of lossless and gainless components of the waveguide in addition to changing the sign of passive and active elements while applying a glide-symmetry operation. This GT-symmetry condition allows three Floquet-Bloch eigenmodes of the structure to coalesce to a real-valued wave number at a single frequency, in addition to having one branch of the dispersion diagram with a purely real wave number. The proposed scheme may have applications including but not limited to distributed amplifiers, radiating arrays, and sensors, from radio frequency to optics.
We measure the propagation loss in trivial and topological slow-light guided interface modes of a valley-Hall photonic topological insulator indicating that there is no topological protection from fabrication-induced ...
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ISBN:
(纸本)9781957171258
We measure the propagation loss in trivial and topological slow-light guided interface modes of a valley-Hall photonic topological insulator indicating that there is no topological protection from fabrication-induced disorder.
Supercontinuum generation has been widely investigated as a way to considerably extend the span of an optical frequency comb, while maintaining its coherence. One area of application is gas-phase spectroscopy in the m...
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ISBN:
(纸本)9798350345995
Supercontinuum generation has been widely investigated as a way to considerably extend the span of an optical frequency comb, while maintaining its coherence. One area of application is gas-phase spectroscopy in the molecular-fingerprint mid-infrared region. 4H-Silicon-Carbide (SiC) on insulator has emerged as a competitive platform for non-linear optics. Recent progress in the fabrication process of waveguides have lowered the propagation loss down to 0.08 dB/cm [1], while the material exhibits strong second and third order optical nonlinearities, a wide transparency window, and a high refractive index contrast with the silica cladding.
A novel on-chip spectrometer based on top-down imaging of a multi-mode interference waveguide is introduced. Accurate wavelength identification with 0.5 nm resolution is demonstrated using a machine learning based, mu...
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ISBN:
(纸本)9781957171258
A novel on-chip spectrometer based on top-down imaging of a multi-mode interference waveguide is introduced. Accurate wavelength identification with 0.5 nm resolution is demonstrated using a machine learning based, multi-point spectral reconstruction process.
Dispersion-engineered silicon-carbide waveguides generate dispersive waves at visible and mid-infrared wavelengths as long as 4 µm. The energy of the seed 70-fs pulses centered at 1.5-µm can be as low as 200...
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ISBN:
(纸本)9781957171258
Dispersion-engineered silicon-carbide waveguides generate dispersive waves at visible and mid-infrared wavelengths as long as 4 µm. The energy of the seed 70-fs pulses centered at 1.5-µm can be as low as 200 pJ.
We demonstrate low-power thermal refractive index trimming of silicon nitride waveguides using suspended heaters. An average effective index change of -2.6×10 -3 was achieved at a wavelength of 1550 nm with a po...
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ISBN:
(纸本)9781957171258
We demonstrate low-power thermal refractive index trimming of silicon nitride waveguides using suspended heaters. An average effective index change of -2.6×10 -3 was achieved at a wavelength of 1550 nm with a power dissipation of 40mW after 1.5 hours.
We study analytically and numerically the formation of bound states in the continuum (BICs) in quantum-mechanical and optical spatially symmetric multimode waveguide systems. The widely used Friedrich-Wintgen model pr...
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We study analytically and numerically the formation of bound states in the continuum (BICs) in quantum-mechanical and optical spatially symmetric multimode waveguide systems. The widely used Friedrich-Wintgen model predicts a BIC for two (nearly) degenerate eigenstates of the resonator. However, numerical calculations typically show that BICs may appear away from the degeneracy point (or avoided crossing region) in the energy-parameter space. From the two-mode point of view based on the Friedrich-Wintgen model, such BICs can be considered as accidental. In this paper, we go beyond the two-mode approximation and, appealing to the notion of intermode bound states, provide an illustrative procedure for deriving conditions for BIC formation within an arbitrary finite-mode approximation. In particular, we show that a three-mode approximation allows the description of a continuous transition of a BIC between different pairs of modes, which can be associated with it within the two-mode model. Also, a manifestation of exceptional points as (anti)resonance coalescence is discussed. Analytical conclusions are verified by the results of numerical simulations of two-dimensional quantum-mechanical and optical stubbed waveguides with confining impurities in the stub. Moreover, numerical simulations confirm the existence of BICs in optical subwavelength resonators, which were earlier predicted in quantum-mechanical waveguides.
Spin-wave based transmission and processing of information is a promising emerging nanotechnology that can help overcome limitations of traditional electronics based on the transfer of electrical charge. Among the mos...
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We experimentally demonstrate a sub-150μW average pump power supercontinuum generation in the midinfrared, ranging from 4 to 10.5μm wavelength, using low loss, highly nonlinear graded-index Ge-rich SiGe waveguides a...
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ISBN:
(纸本)9798350345995
We experimentally demonstrate a sub-150μW average pump power supercontinuum generation in the midinfrared, ranging from 4 to 10.5μm wavelength, using low loss, highly nonlinear graded-index Ge-rich SiGe waveguides and dispersion management along the propagation.
We demonstrate silicon nitride waveguides with <0.1 and 0.3 dB/cm loss in nitride and fully integrated photonics wafers, respectively, by employing noble integration techniques while preserving the performance of t...
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ISBN:
(纸本)9781957171258
We demonstrate silicon nitride waveguides with <0.1 and 0.3 dB/cm loss in nitride and fully integrated photonics wafers, respectively, by employing noble integration techniques while preserving the performance of the other devices of the platform.
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