International Journal of Physics | Vol. 8, No. 12, December 2017 | pp. 89–96
DOI: 10.46882/2017/IJP/000092
Research Article
Title: Optical Properties and Exciton Dynamics of Monolayer Molybdenum Diselenide on Silicon Nitride Waveguides
Names of Authors: Y. S. Kim¹, T. H. Nguyen²
Authors’ Affiliations: ¹Department of Physics and Astronomy, Seoul National University, Seoul, South Korea; ²Department of Physics, Vietnam National University, Hanoi, Vietnam
Abstract: Monolayer transition metal dichalcogenides have attracted significant interest due to their strong light-matter interactions and potential for integrated nanophotonic circuits. This study characterizes the optical properties and exciton dynamics of monolayer molybdenum diselenide (MoSe²) integrated onto silicon nitride wave-guiding structures. The monolayer flakes were synthesized via chemical vapor deposition and transferred onto the waveguides using an optimized dry-transfer technique. We performed micro-photoluminescence and angle-resolved reflectivity measurements under mechanical tensile strains from 0.0% to 1.6% at a room temperature of 300 K. The unstrained monolayer coupled to the evanescent field of the waveguide exhibits strong absorption lines, confirming efficient evanescent phase-coupling. Applying a 1.0% tensile strain shifts the exciton resonance energy from 1.55 eV to 1.49 eV, yielding a strain tuning factor of 60.0 meV/% strain. Time-resolved photoluminescence spectroscopy revealed a shortened polariton decay lifetime, dropping from 16.5 ps down to 5.2 ps due to the dielectric Purcell effect. Our numerical models confirm that the localized electromagnetic field confinement within the silicon nitride core increases the exciton-photon coupling rate by 35.0%. These findings demonstrate that waveguide-integrated strain engineering offers an effective route for controlling exciton-polariton states in thin-film optoelectronic architectures.
Keywords: Molybdenum diselenide; silicon nitride; photoluminescence; exciton dynamics; tensile strain; integrated photonics
Manuscript Timeline: Received: August 18, 2017; Revised: October 10, 2017; Accepted: November 02, 2017; Published: December 15, 2017
Citation: Kim, Y. S., & Nguyen, T. H. (2017). Optical Properties and Exciton Dynamics of Monolayer Molybdenum Diselenide on Silicon Nitride Waveguides. International Journal of Physics, 8(12), 89–96.
International Journal of Physics | Vol. 8, No. 11, November 2017 | pp. 81–88
DOI: 10.46882/2017/IJP/000091
Research Article
Title: Optical Soliton Dynamics and Instabilities in Non-Local Plasma Metamaterials with Higher-Order Non-Linearities
Names of Authors: S. H. Zhang¹, P. L. Becker²
Authors’ Affiliations: ¹Department of Physics, Tsinghua University, Beijing, China; ²Institute for Plasma Research, University of Stuttgart, Stuttgart, Germany
Abstract: Designing optical plasma systems that can stabilize ultra-short laser pulses or safely mitigate high-power filamentation is crucial for advanced plasma torch development and optical particle tracking. This paper solves the generalized non-linear Schrödinger equation governing optical soliton perturbations and models rogue wave formations within non-local plasma metamaterials exhibiting cubic-quintic non-linearities. The mathematical model includes higher-order perturbation terms, specifically third-order dispersion, self-steepening, and inter-file Raman scattering delays. We apply the inverse scattering transform method alongside a multiple-scale perturbation algorithm to derive analytical solutions for single-soliton structures and breathers. The results show that a high degree of spatial non-locality effectively suppresses collapse modes, stabilizing two-dimensional structures that are unstable in local Kerr media. The modulational instability growth rate was calculated as a function of perturbation frequency, revealing a maximum gain value of g = 2.92 cm^-1 under an input intensity of 2.0 kW/cm². Increasing the non-locality parameter from 1.0 mm to 5.0 mm reduces the maximum instability gain by 68.0% and shifts the peak gain toward longer perturbation wavelengths, preventing catastrophic pulse fragmentation.
Keywords: Nonlinear optics; spatial solitons; nonlinear Schrödinger equation; modulational instability; non-local media; split-step Fourier method
Manuscript Timeline: Received: July 12, 2017; Revised: September 04, 2017; Accepted: September 22, 2017; Published: November 14, 2017
Citation: Zhang, S. H., & Becker, P. L. (2017). Optical Soliton Dynamics and Instabilities in Non-Local Plasma Metamaterials with Higher-Order Non-Linearities. International Journal of Physics, 8(11), 81–88.
International Journal of Physics | Vol. 8, No. 10, October 2017 | pp. 73–80
DOI: 10.46882/2017/IJP/000090
Research Article
Title: Superconducting Gap Structure and Spin Fluctuations in Electron-Doped Pnictide SmFeAsO0.80F0.20 Single Crystals
Names of Authors: I. R. Sokolov¹, A. A. Menshikov²
Authors’ Affiliations: ¹Kapitza Institute for Physical Problems, Russian Academy of Sciences, Moscow, Russia; ²Institute for Solid State Physics, Russian Academy of Sciences, Chernogolovka, Russia
Abstract: Uncovering the exact pairing symmetry of iron-based pnictide superconductors remains a primary challenge in modern condensed matter physics. We synthesized high-quality single crystals of electron-doped SmFeAsO0.80F0.20 utilizing a high-pressure flux growth methodology at 5.0 GPa. The superconducting gap structure and spin fluctuations were evaluated through high-resolution angle-resolved photoemission spectroscopy and low-temperature London penetration depth measurements. The single crystals exhibited a sharp superconducting transition at Tc = 52.5 K with a magnetic susceptibility transition width of ΔT = 0.4 K. The temperature dependence of the London penetration depth shows an exponential behavior at low temperatures (T less than 0.3 Tc), which rules out the presence of line nodes in the order parameter. The photoemission spectra revealed two distinct, fully gapped isotropic superconducting bands. The larger gap value was measured at Δ1 = 14.2 meV on the inner hole-like Fermi surface sheet, while the smaller gap was found at Δ2 = 7.1 meV on the electron-like sheets. This gap configuration yields a strong-coupling ratio of 2Δ1/kBTc = 6.2, indicating strong-coupling superconductivity. These experimental results align with the s± pairing symmetry model driven by interband spin fluctuations.
Keywords: Iron-based superconductors; gap structure; angle-resolved photoemission spectroscopy; London penetration depth; pairing symmetry; spin fluctuations
Manuscript Timeline: Received: June 04, 2017; Revised: July 28, 2017; Accepted: August 18, 2017; Published: October 13, 2017
Citation: Sokolov, I. R., & Menshikov, A. A. (2017). Superconducting Gap Structure and Spin Fluctuations in Electron-Doped Pnictide SmFeAsO0.80F0.20 Single Crystals. International Journal of Physics, 8(10), 73–80.
International Journal of Physics | Vol. 8, No. 9, September 2017 | pp. 65–72
DOI: 10.46882/2017/IJP/000089
Research Article
Title: Squeezed Vacuum State Propagation and Optomechanical Coupling Dynamics in Disordered Microdisk Resonators
Names of Authors: A. M. Ross¹, D. W. Meyer²
Authors’ Affiliations: ¹Department of Physics, University of Queensland, Brisbane, QLD 4072, Australia; ²Institute of Physics, Karlsruher Institut für Technologie, Karlsruhe, Germany
Abstract: Maintaining quantum state correlations across integrated optical networks is crucial for building fault-tolerant quantum computing architectures and secure communication lines. This paper models continuous-wave squeezed vacuum state propagation and characterizes optomechanical coupling dynamics within a linear array of coupled silica microdisk resonators subjected to spatial fabrication disorder. We solved the quantum stochastic Schrödinger equations using an algebraic operator framework that accounts for localized evanescent coupling variations, cavity mirror losses, and thermal phonon dephasing at 4.2 K. Squeezed vacuum states at 1550.0 nm were injected into the boundary cavity of a 15-channel system. The calculations demonstrate that introducing a 4.0% structural disorder in cavity resonance frequencies induces strong spatial localization of light. This localization reduces the squeezing level in the primary channel from 8.0 dB down to 2.4 dB over a brief 12.0 ps interaction window. To protect the quantum states, we simulated an active phase-modulation feedback sequence. This sequence establishes a synthetic gauge field that suppresses backscattering and locks the relative phase of the local oscillator. The optimized array configuration successfully restored the squeezing level to 6.8 dB at the output port, yielding a state fidelity calculation of 94.8% ± 0.3%.
Keywords: Quantum optics; squeezed states; optical cavities; optomechanics; cavity arrays; integrated photonics
Manuscript Timeline: Received: May 12, 2017; Revised: July 03, 2017; Accepted: July 25, 2017; Published: September 11, 2017
Citation: Ross, A. M., & Meyer, D. W. (2017). Squeezed Vacuum State Propagation and Optomechanical Coupling Dynamics in Disordered Microdisk Resonators. International Journal of Physics, 8(9), 65–72.
International Journal of Physics | Vol. 8, No. 8, August 2017 | pp. 57–64
DOI: 10.46882/2017/IJP/000088
Research Article
Title: Finite Element Modeling of Acoustic Wave Scattering and Focus Tuning in Poroelastic Acoustic Lenses
Names of Authors: P. J. O’Connor¹, G. S. Campbell²
Authors’ Affiliations: ¹Department of Civil and Environmental Engineering, University College Cork, Cork, Ireland; ²Research School of Physics and Engineering, Australian National University, Canberra, Australia
Abstract: Controlling acoustic focal positions and intensities in underwater and marine structural environments is essential for non-destructive testing, ultrasound medical imaging, and sonar technologies. This study implements a finite element modeling approach to simulate acoustic wave scattering and focus tuning within gradient-index poroelastic acoustic lenses. The design leverages a coordinate-transformation method applied to Biot's dynamic poroelastic equations to determine the required anisotropic distribution of density and elastic moduli tensors across the lens. We performed numerical scattering simulations across an ultrasonic frequency band from 30.0 kHz to 120.0 kHz. The computational models show that a hyperbolic lens constructed with 32 concentric sub-wavelength layers successfully concentrates an incident acoustic wave to a localized spot. This configuration increases the total acoustic energy density at the focal point by 12.0 dB at a design frequency of 80.0 kHz. We analyzed the impact of fluid viscosity on lensing performance, finding that viscous dissipation in the porous channels dampens higher-order harmonic fields. This damping restricts forward transmission to a minor 5.5% energy loss. Experimental validation was carried out using 3D-printed perforated elastomeric matrices immersed in water. The measured pressure fields matched the simulated profiles within a ±5.0% margin.
Keywords: Acoustic metamaterials; finite element modeling; acoustic lenses; Biot's theory; focus tuning; porous media
Manuscript Timeline: Received: April 15, 2017; Revised: June 02, 2017; Accepted: June 22, 2017; Published: August 18, 2017
Citation: O’Connor, P. J., & Campbell, G. S. (2017). Finite Element Modeling of Acoustic Wave Scattering and Focus Tuning in Poroelastic Acoustic Lenses. International Journal of Physics, 8(8), 57–64.
International Journal of Physics | Vol. 8, No. 7, July 2017 | pp. 49–56
DOI: 10.46882/2017/IJP/000087
Research Article
Title: Fluid Inflow Velocity Mapping and Reconnection Energetics in Solar Chromospheric Flares
Names of Authors: G. R. Davies¹, C. H. Jenkins²
Authors’ Affiliations: ¹School of Physics and Astronomy, University of St Andrews, St Andrews, UK; ²Space Sciences Laboratory, University of California, Berkeley, California, USA
Abstract: Magnetic reconnection is the fundamental plasma driver behind explosive energy release events in the solar atmosphere, accelerating solar winds and triggering coronal mass ejections. This paper maps fluid inflow velocities and analyzes reconnection energetics within a solar chromospheric active region using high-resolution data from satellite ultraviolet spectrometers. We tracked the Doppler shifts and intensity profiles of the Mg II and C II spectral emission lines to isolate reconnection pathways under low-temperature, high-density conditions. The empirical measurements reveal localized plasma inflows moving at 12.4 km/s, while directed outflows reach velocities of 185.0 km/s into the active coronal loops. Based on these transport metrics, the local dimensionless reconnection rate was calculated to range between 0.04 and 0.07. These values closely align with fast reconnection regimes predicted by the Sweet-Parker theoretical framework modified by hall magnetohydrodynamic effects and plasmoid instabilities. Spectroscopic line-broadening analysis indicates localized turbulent temperatures peaking at 4.5 MK within the current sheet boundary. This high temperature confirms intense localized viscous dissipation. These spectroscopic diagnostics provide direct observational constraints for refining magnetohydrodynamic models of chromospheric heating networks.
Keywords: Solar atmosphere; magnetic reconnection; solar flares; ultraviolet spectroscopy; plasma velocity; magnetohydrodynamics
Manuscript Timeline: Received: March 20, 2017; Revised: May 05, 2017; Accepted: May 28, 2017; Published: July 14, 2017
Citation: Davies, G. R., & Jenkins, C. H. (2017). Fluid Inflow Velocity Mapping and Reconnection Energetics in Solar Chromospheric Flares. International Journal of Physics, 8(7), 49–56.