Coherent frequency generators are an enabling platform in basic science and applied technology. Originally reliant on high-power lasers, recently comb generation has been demonstrated in ultrahigh- microcavities. The large circulating intensity within the cavity results in strong light-matter interaction, giving rise to Kerr parametric oscillations for comb generation. However, the comb generation threshold is limited by competing nonlinear effects within the cavity material and low intrinsic material Kerr coefficients. We report a new strategy to fabricate near-infrared frequency combs based on combining high- microcavities with monomolecular layers of highly nonlinear small molecules. The functionalized microcavities demonstrate high-efficiency parametric oscillation in the near-IR and generate primary frequency combs with 0.88-mW thresholds, improving optical parametric oscillation generation over nonfunctionalized devices by three orders of magnitude. This organic-inorganic approach enables otherwise unattainable performance and will inspire the next generation of integrated photonic device platforms.
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http://dx.doi.org/10.1126/sciadv.aao4507 | DOI Listing |
Nature
January 2025
Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
The integrated frequency comb generator based on Kerr parametric oscillation has led to chip-scale, gigahertz-spaced combs with new applications spanning hyperscale telecommunications, low-noise microwave synthesis, light detection and ranging, and astrophysical spectrometer calibration. Recent progress in lithium niobate (LiNbO) photonic integrated circuits (PICs) has resulted in chip-scale, electro-optic (EO) frequency combs, offering precise comb-line positioning and simple operation without relying on the formation of dissipative Kerr solitons. However, current integrated EO combs face limited spectral coverage due to the large microwave power required to drive the non-resonant capacitive electrodes and the strong intrinsic birefringence of LiNbO.
View Article and Find Full Text PDFJ Org Chem
January 2025
Division of Theoretical Chemistry, IFM, Linköping University, 58183 Linköping, Sweden.
The harmonic oscillator model of aromaticity (HOMA) offers a straightforward route to quantifying aromaticity that requires no other information than the bond lengths of the conjugated ring in question. Given that such information is often readily obtainable from quantum-chemical calculations, it is pertinent to improve this parametrized model as much as possible. Here, a new version of HOMA is presented where, atypically, the corresponding parameters are derived from the actual bond lengths of both aromatic and antiaromatic (rather than nonaromatic) reference compounds, as calculated with a high-level method.
View Article and Find Full Text PDFAnal Chem
January 2025
Joint Mass Spectrometry Centre/Chair of Analytical Chemistry, University of Rostock, 18059 Rostock, Germany.
To our knowledge, this study presents the first implementation of wavelength-resolved resonance-enhanced multiphoton ionization (REMPI) spectroscopy under atmospheric pressure ionization conditions using a high-resolution mass spectrometric system. Atmospheric pressure laser ionization MS spectroscopic measurements were conducted on over 70 different polycyclic aromatic hydrocarbons (PAHs) and hetero-PAHs (N, S, and O) in standard solutions, as well as three complex PAH-containing samples. The results demonstrate the successful transfer of REMPI spectroscopy from vacuum to atmospheric pressure conditions, maintaining spectral integrity without significant band broadening.
View Article and Find Full Text PDFPhys Rev E
November 2024
Department of Mathematical Engineering, Musashino University, Tokyo 135-8181, Japan.
Pulse generation in a spatially extended system is studied numerically. Using an array of coupled excitable oscillators, pulse generation is achieved by introducing a parametric heterogeneity between the two partitions of the array. The profile of the propagating pulses can be regulated using the parameter mismatch between these two partitions.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Mathematics, College of Science, King Khalid University, Abha, Saudi Arabia.
In light of the ponderomotive force, this article focuses on establishing the exact wave structures of the ion sound system. It is the result of non-linear force and affects a charged particle oscillating in an inhomogeneous electromagnetic field. By using the Riemann-Liouville operator, -operator, and Atangana-Baleanu fractional analysis, the examined equation-which consists of the normalized electric field of the Langmuir oscillation and normalized density perturbation-is thoroughly examined.
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