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17 pages, 8553 KB

Open AccessArticle

Observation of Near-Inertial Oscillation in an Anticyclonic Eddy in the Northern South China Sea

by Botao Xie, Tao Liu, Bigui Huang, Chujin Liang and Feilong Lin

J. Mar. Sci. Eng. 2025, 13(6), 1079; https://doi.org/10.3390/jmse13061079 - 29 May 2025

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Anticyclonic mesoscale eddies are known to trap and modulate near-inertial kinetic energy (NIKE); however, the spatial distribution of NIKE within the eddy core and periphery, as well as the mechanisms driving its energy cascade to smaller scales, remains inadequately understood. This study analyzed the evolution of NIKE in anticyclonic eddies using satellite altimetry and field observations from four mooring arrays. By extracting near-inertial oscillations (NIOs) and subharmonic wave kinetic energy across mooring stations during the same period, we characterized the spatial structure of NIKE within the eddy field. The results revealed that NIKE was concentrated in the eddy core, where strong NIOs (peak velocity ~0.23 m/s) persisted for ~7 days, with energy primarily distributed at depths of 200–400 m and propagating inward from the periphery. Subharmonic waves fD1 generated by interactions between NIOs and diurnal tides highlighted the role of the vertical nonlinear term in energy transfer. A further analysis indicated that under vorticity confinement, NIKE accumulated in the core of the eddy and dissipated through shear instability and nonlinear wave interactions. The migrating anticyclonic eddy thus acted as a localized energy source, driving mixing and energy dissipation in the ocean interior. Full article

(This article belongs to the Special Issue Ocean Internal Waves and Circulation Dynamics in Climate Change)

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33 pages, 14062 KB

Open AccessArticle

Parametric Characterization of Nonlinear Optical Susceptibilities in Four-Wave Mixing: Solvent and Molecular Structure Effects

by José L. Paz, Alberto Garrido-Schaeffer, Marcos A. Loroño, Lenin González-Paz, Edgar Márquez, José R. Mora and Ysaias J. Alvarado

Symmetry 2024, 16(10), 1263; https://doi.org/10.3390/sym16101263 - 25 Sep 2024

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Abstract

We study the nonlinear absorptive and dispersive optical properties of molecular systems immersed in a thermal reservoir interacting with a four-wave mixing (FWM) signal. Residual spin-orbit Hamiltonians are considered in order to take into account the internal structure of the molecule. As system parameters in the dissipation processes, transverse and longitudinal relaxation times are considered for stochastic solute–solvent interaction processes. The intramolecular coupling effects on the optical responses are studied using a molecule model consisting of two coupled harmonic curves of electronic energies with displaced minima in nuclear energies and positions. In this study, the complete frequency space is considered through the pump–probe detuning, without restricting the derivations to only maximums of population oscillations. This approach opens the possibility of studying the behavior of optical responses, which is very useful in experimental design. Our results indicate the sensitivity of the optical responses to parameters of the molecular structure as well as to those derived from the photonic process of FWM signal generation. Full article

(This article belongs to the Section Physics)

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11 pages, 3096 KB

Open AccessEditor’s ChoiceCommunication

Frequency Comb Fiber Generator Based on Photonic Bandgap Amplifier

by Aleksei Abramov, Dmitry Korobko and Igor Zolotovskii

Photonics 2023, 10(9), 965; https://doi.org/10.3390/photonics10090965 - 23 Aug 2023

Cited by 2 | Viewed by 1651

Abstract

We report on a model of a fiber frequency comb generator that develops an approach to harmonically mode-locked fiber laser design based on dissipative four-wave mixing. In our version of this approach, we assume an amplifying one-dimensional photonic crystal as a key cavity element combining the properties of an intra-cavity filter and a power amplifier. Using standard equations describing the signal transformation in the ring cavity and the output fiber cascade, we have demonstrated the possibility of the application of the proposed model as a generator of broadband frequency comb with controllable line spacing. Full article

(This article belongs to the Special Issue Optical Fiber Lasers and Amplifiers. Practical Applications of Fiber-Based Laser Sources)

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12 pages, 6447 KB

Open AccessCommunication

Wavelength-Tunable L-Band High Repetition Rate Erbium-Doped Fiber Laser Based on Dissipative Four-Wave Mixing

by Kai Li, Qianqian Huang, Junjie Jiang, Zinan Huang and Chengbo Mou

Sensors 2021, 21(17), 5975; https://doi.org/10.3390/s21175975 - 6 Sep 2021

Cited by 8 | Viewed by 3344

Abstract

A wavelength-tunable high repetition rate (HRR) erbium-doped fiber laser in L-band based on dissipative four-wave mixing (DFWM) mechanism is demonstrated. The cavity can generate a single-soliton train and bound-soliton train with a fixed repetition rate of ~126 GHz, which is determined by the free spectral range of the intra-cavity Lyot filter. A wide wavelength-tuning operation can also be obtained by rotating the polarization controllers. The wavelength-tuning ranges of the HRR single-soliton state and HRR bound-soliton state are ~38.3 nm and ~22.6 nm, respectively. This laser provides useful references for the area of a wavelength-tunable fiber laser with high repetition rate. The laser may also find useful applications in high-speed communication, sensing, etc. Full article

(This article belongs to the Special Issue Advanced Fiber Photonic Devices and Sensors)

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15 pages, 1554 KB

Open AccessArticle

Integrated Source of Path-Entangled Photon Pairs with Efficient Pump Self-Rejection

by Pablo de la Hoz, Anton Sakovich, Alexander Mikhalychev, Matthew Thornton, Natalia Korolkova and Dmitri Mogilevtsev

Nanomaterials 2020, 10(10), 1952; https://doi.org/10.3390/nano10101952 - 30 Sep 2020

Cited by 5 | Viewed by 3486

Abstract

We present a theoretical proposal for an integrated four-wave mixing source of narrow-band path-entangled photon pairs with efficient spatial pump self-rejection. The scheme is based on correlated loss in a system of waveguides in Kerr nonlinear media. We calculate that this setup gives the possibility for upwards of 100 dB pump rejection, without additional filtering. The effect is reached by driving the symmetric collective mode that is strongly attenuated by an engineered dissipation, while photon pairs are born in the antisymmetric mode. A similar set-up can additionally be realized for the generation of two-photon NOON states, also with pump self-rejection. We discuss the implementation of the scheme by means of the coherent diffusive photonics, and demostrate its feasibility in both glass (such as fused silica-glass and IG2) and planar semiconductor waveguide structures in indium phosphide (InP) and in silicon. Full article

(This article belongs to the Special Issue Nonlinear and Quantum Optics with Nanostructures)

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