Photon Field Research Articles

Understanding the TeV γ-ray emission surrounding the young massive star cluster Westerlund 1

Context. Young massive star clusters (YMCs) have increasingly become the focus of discussions on the origin of galactic cosmic rays (CRs). The proposition that CRs are accelerated inside superbubbles (SBs) blown by the strong winds of these clusters avoids issues faced by the standard paradigm of acceleration at supernova remnant shocks. Aims. We provide an interpretation of the latest TeV γ-ray observations of the region around the YMC Westerlund 1 taken with the High Energy Stereoscopic System (H.E.S.S.) in terms of diffusive shock acceleration at the cluster wind termination shock, taking the spectrum and morphology of the emission into account. As Westerlund 1 is a prototypical example of a YMC, this study is relevant to the general question about the role of YMCs for the Galactic CR population. Methods. We generated model γ-ray spectra, characterised particle propagation inside the SB based on the advection, diffusion, and cooling timescales, and constrained key parameters of the system. We considered hadronic emission from proton-proton interaction and subsequent pion decay and leptonic emission from inverse Compton scattering on all relevant photon fields, including the cosmic microwave background, diffuse and dust-scattered starlight, and the photon field of Westerlund 1 itself. The effect of the magnetic field on cooling and propagation is discussed. Klein-Nishina effects are found to be important in determining the spectral evolution of the electron population. Results. A leptonic origin of the bulk of the observed γ-rays is preferable. The model is energetically plausible, consistent with the presence of a strong shock, and allows for the observed energy-independent morphology. The hadronic model faces two main issues: confinement of particles to the emission region, and an unrealistic energy requirement.

Laser Safety in Army Education

Abstract Studies have been made on the development of military science and it has been established that for the modernization of the army and the defense industry it is necessary to develop and search for new innovative technological solutions in the field of laser technology and photonics. According to the trends in the use of laser technologies for military applications, the need to acquire knowledge in the field of “Laser Safety” has also been proven. The report substantiates the need to train cadets and students in a military university. A curriculum on “Laser Safety” is proposed and what knowledge and skills future officers should acquire are indicated.

Strain-Relaxed Nanocrystalline Diamond Thin Films with Silicon Vacancy Centers Using Femtosecond Laser Irradiation for Photonic Applications

Nanocrystalline diamond thin (thickness of 100–500 nm) films with ensembles of negatively charged light-emitting silicon vacancy (SiV) centers might find an application in the field of photonics or biosensing due to their scalable and low-price fabrication process in comparison with monocrystalline diamond. The potential application of diamond thin films is, however, limited due to the presence of radiative and nonradiative defects. The former type is a source of an unwanted background in the photoluminescence spectra, the latter lowers the quantum efficiency of light emission, and both types of defects cause the reabsorption of SiV emission during its propagation within the layer. Here we show that femtosecond (fs) laser pulses focused via a microscope objective on a nanocrystalline diamond thin film can be employed to reduce background photoluminescence intensity by a factor of 5 with respect to the luminescence of SiV centers. Raman spectra show that this decrease is mainly caused by laser ablation of the sp2-related carbon phase present in-between the grains. The reduction of the sp2 carbon phase also leads to a local decrease in the optical absorption followed by an almost twofold increase in the SiV emission peak intensity. Moreover, the fs-irradiation also entails the release of strain inside such a layer as manifested by the observed shift of the Raman diamond peak toward the value measured in the monocrystalline diamond and by a blue-shift of the zero-phonon-line peak position of the SiV centers. Such a finding might enable the improvement of the optical quality of the nanocrystalline diamond-based photonic nanostructures or even might be employed over a larger area by defocusing the irradiation laser in order to create large-scale strain-relaxed nanocrystalline diamond thin films.

Nonlinear optical properties of superalkali@teetotum boron clusters with potential applications on the electro-optic modulator

The development of nonlinear optics has revolutionized the photonic and optoelectronic fields in recent years.In this paper, we have designed a new class of donor–acceptor frameworks with enhanced nonlinear optical (NLO)properties using a series of superalkalis including Li3O, Li2NaO, LiNa2O, Li2KO, LiK2O as donors and three sizes of teetotum boron clusters (B14, B18, and B22) as acceptors. A systematic first-principles study has been performed on the electronic, linear, and NLO properties of superalkali@Bnassemblies. Besides the static non-linearity, the frequency-dependent electro-optic Pockel's effect (EOPE), second harmonic generation (SHG), and nonlinear refractive index have also been evaluated. In the case of dynamic NLO, the SHG process has a stronger NLO response than EOPE. At the typical experimental frequency of the Nd:YAG laser (ω = 0.04282) a.u., the SHG coefficients are about 2–3 times larger than the corresponding EOPE at this wavelength. Also, the nonlinear refractive index shows a remarkable response atω = 0.04 a.u. for LiK2O@B14.

Renormalization in Quantum Brain Dynamics

We show renormalization in Quantum Brain Dynamics (QBD) in 3+1 dimensions, namely Quantum Electrodynamics with water rotational dipole fields. First, we introduce the Lagrangian density for QBD involving terms of water rotational dipole fields, photon fields and their interactions. Next, we show Feynman diagrams with 1-loop self-energy and vertex function in dipole coupling expansion in QBD. The counter-terms are derived from the coupling expansion of the water dipole moment. Our approach will be applied to numerical simulations of Kadanoff–Baym equations for water dipoles and photons to describe the breakdown of the rotational symmetry of dipoles, namely memory formation processes. It will also be extended to the renormalization group method for QBD with running parameters in multi-scales.

Artificial Non-Abelian Lattice Gauge Fields for Photons in the Synthetic Frequency Dimension.

Non-Abelian gauge fields give rise to nontrivial topological physics. Here we develop a scheme to create an arbitrary SU(2) lattice gauge field for photons in the synthetic frequency dimension using an array of dynamically modulated ring resonators. The photon polarization is taken as the spin basis to implement the matrix-valued gauge fields. Using a non-Abelian generalization of the Harper-Hofstadter Hamiltonian as a specific example, we show that the measurement of the steady-state photon amplitudes inside the resonators can reveal the band structures of the Hamiltonian, which show signatures of the underlying non-Abelian gauge field. These results provide opportunities to explore novel topological phenomena associated with non-Abelian lattice gauge fields in photonic systems.

Origin of multiwavelength emission from flaring high redshift blazar PKS 0537−286

ABSTRACT The high redhsift blazars powered by supermassive black holes with masses exceeding 109 M⊙ have the highest jet power and luminosity and are important probes to test the physics of relativistic jets at the early epochs of the Universe. We present a multifrequency spectral and temporal study of high redshift blazar PKS 0537−286 by analysing data from Fermi-LAT, NuSTAR Swift XRT, and UVOT. Although the time averaged γ-ray spectrum of the source is relatively soft (indicating the high-energy emission peak is below the GeV range), several prominent flares were observed when the spectrum hardened and the luminosity increased above 1049 erg s−1. The X-ray emission of the source varies in different observations and is characterized by a hard spectrum ≤1.38 with a luminosity of >1047 erg s−1. The broad-band spectral energy distribution in the quiescent and flaring periods was modelled within a one-zone leptonic scenario assuming different locations of the emission region and considering both internal (synchrotron radiation) and external (from the disc, broad-line region, and dusty torus) photon fields for the inverse Compton scattering. The modelling shows that the most optimistic scenario, from the energy requirement point of view, is when the jet energy dissipation occurs within the broad-line region. The comparison of the model parameters obtained for the quiescent and flaring periods suggests that the flaring activities are most likely caused by the hardening of the emitting electron spectral index and shifting of the cut-off energy to higher values.

Circuit quantum electrodynamic model of dissipative-dispersive Josephson traveling-wave parametric amplifiers

We present a quantum mechanical model for a four-wave mixing Josephson traveling-wave parametric amplifier including substrate losses and associated thermal fluctuations. Under the assumption of a strong undepleted classical pump tone, we derive an analytic solution for the bosonic annihilation operator of the weak signal photon field using temporal equations of motion in a reference timeframe, including chromatic dispersion. From this result, we can predict the asymmetric gain spectrum of a Josephson traveling-wave parametric amplifier due to non-zero substrate losses. We also predict the equivalent added input noise including quantum fluctuations as well as thermal noise contributions. Our results are in excellent agreement with recently published experimental data.

Carbonization of a Molybdenum Substrate Surface and Nanoparticles by a One-Step Method of Femtosecond Laser Ablation in a Hexane Solution.

Molybdenum carbides (MoC and Mo2C) are being reported for various applications, for example, catalysts for sustainable energies, nonlinear materials for laser applications, protective coatings for improving tribological performance, and so on. A one-step method for simultaneously fabricating molybdenum monocarbide (MoC) nanoparticles (NPs) and MoC surfaces with a laser-induced periodic surface structure (LIPSS) was developed by using pulsed laser ablation of a molybdenum (Mo) substrate in hexane. Spherical NPs with an average diameter of 61 nm were observed by scanning electron microscopy. The X-ray diffraction pattern and electron diffraction (ED) pattern results indicate that a face-centered cubic MoC was successfully synthesized for the NPs and on the laser-irradiated area. Notably, the ED pattern suggests that the observed NPs are nanosized single crystals, and a carbon shell was observed on the surface of MoC NPs. The X-ray diffraction pattern of both MoC NPs and LIPSS surface indicates the formation of FCC MoC, agreeing with the results of ED. The results of X-ray photoelectron spectroscopy also showed the bonding energy attributed to Mo-C, and the sp2-sp3 transition was confirmed on the LIPSS surface. The results of Raman spectroscopy have also supported the formation of MoC and amorphous carbon structures. This simple synthesis method for MoC may provide new possibilities for preparing Mo x C-based devices and nanomaterials, which may contribute to the development of catalytic, photonic, and tribological fields.

Positronium density measurements using polaritonic effects

Recent experimental advances in Positronium (Ps) physics have made it possible to produce dense Ps ensembles in which Ps-Ps interactions may occur, leading to the production of Ps$_2$ molecules and paving the way to the realization of a Ps Bose-Einstein Condensate (BEC). In order to achieve this latter goal it would be advantageous to develop new methods to measure Ps densities in real-time. Here we describe a possible approach to do this using polaritonic methods: using realistic experimental parameters we demonstrate that a dense Ps gas can be strongly coupled to the photonic field of a distributed Bragg reflector microcavity. In this strongly coupled regime, the optical spectrum of the system is composed of two hybrid positronium-polariton resonances separated by the vacuum Rabi splitting, which is proportional to the square root of the Ps density. Given that polaritons can be created on a sub-cycle timescale, a spectroscopic measurement of the vacuum Rabi splitting could be used as an ultra-fast Ps density measurement in regimes relevant to Ps BEC formation. Moreover, we show how positronium-polaritons could potentially enter the ultrastrong light-matter coupling regime, introducing a radically novel platform to explore its non-perturbative phenomenology.

Corrections to Hawking radiation from asteroid mass primordial black holes: Formalism of dissipative interactions in quantum electrodynamics

Primordial black holes (PBHs) within the mass range $10^{17} - 10^{22}$ g are a favorable candidate for describing the all of the dark matter content. Towards the lower end of this mass range, the Hawking temperature, $T_{\rm H}$, of these PBHs is $T_{\rm H} \gtrsim 100$ keV, allowing for the creation of electron -- positron pairs; thus making their Hawking radiation a useful constraint for most current and future MeV surveys. This motivates the need for realistic and rigorous accounts of the distribution and dynamics of emitted particles from Hawking radiation in order to properly model detected signals from high energy observations. This is the first in a series of papers to account for the $\mathcal{O}(\alpha)$ correction to the Hawking radiation spectrum. We begin by the usual canonical quantization of the photon and spinor (electron/positron) fields on the Schwarzschild geometry. Then we compute the correction to the rate of emission by standard time dependent perturbation theory from the interaction Hamiltonian. We conclude with the analytic expression for the dissipative correction, i.e. corrections due to the creation and annihilation of electron/positrons in the plasma.

Optical spin-wave detection beyond the diffraction limit

Spin waves are proposed as information carriers for next-generation computing devices because of their low power consumption. Moreover, their wave-like nature allows for novel computing paradigms. Conventional methods to detect propagating spin waves are based either on electrical induction, limiting the downscaling and efficiency complicating eventual implementation, or on light scattering, where the minimum detectable spin-wave wavelength is set by the wavelength of the laser unless near-field techniques are used. In this article, we demonstrate the magneto-optical detection of spin waves beyond the diffraction limit using a metallic grating that selectively absorbs laser light. Specifically, we demonstrate the detection of propagating spin waves with a wavelength of 700nm in 20nm thick Ni80Fe20 strips using a diffraction-limited laser spot with a diameter of 10μm. Additionally, we show that this grating is selective to the wavelength of the spin wave, providing phase-sensitive, wavevector-selective spin-wave detection in the time domain, thus providing a complementary approach to existing techniques such as Brillouin light scattering. This should open up new avenues toward the integration of the burgeoning fields of photonics and magnonics and aid in the optical detection of spin waves in the short-wavelength exchange regime for fundamental research.

The Progress and Trend of Heterogeneous Integration Silicon/III-V Semiconductor Optical Amplifiers

Silicon photonics is a revolutionary technology in the integrated photonics field which has experienced rapid development over the past several decades. High-quality III-V semiconductor components on Si platforms have shown their great potential to realize on-chip light-emitting sources for Si photonics with low-cost and high-density integration. In this review, we will focus on semiconductor optical amplifiers (SOAs), which have received considerable interest in diverse photonic applications. SOAs have demonstrated high performance in various on-chip optical applications through different integration technologies on Si substrates. Moreover, SOAs are also considered as promising candidates for future light sources in the wavelength tunable laser, which is one of the key suitable components in coherent optical devices. Understanding the development and trends of heterogeneous integration Silicon/III-V SOA will help researchers to come up with effective strategies to combat the emerging challenges in this family of devices, progressing towards next-generation applications.

Editorial: Laser field manipulation and its advanced applications

Laser field manipulation is currently one of hot topics in the field of photonics. A wide variety of novel beams, for instance, vectorial vortex beams [1], orbital angular momentum (OAM) comb [2], toroidal vortices [3], high-dimensional beam arrays [4], can be well generated through tailoring various spatial and temporal degrees of freedom (DoFs) as OAM, spin angular momentum (SAM), phase, time/frequency, amplitude, and wave vector. Such novel beams from laser field manipulation have inspired lots of advanced applications covering classical and quantum physics as large-capacity optical communications, lidar, optical tweezer, laser processing, high-dimensional quantum entanglement, and also gravity wave detection [5]. In recent years, many efforts have been paid on laser field manipulation and achieve a leaping development. Hence, to show recent advances in laser field manipulation and their enabled applications, we organize this research topic, and expect to motivate more state-of-art scenarios.The seven published papers in this topic involve both fundamental and engineering research, regarding complex laser field tailoring and applications. M. Zhang et al. In summary, this research topic collects seven representative work of state-of-art laser field manipulation and its advanced applications. We expect this topic will build a bridge of distinct sub-areas integration, and further promote the development of laser field manipulation.

Preface

International Conference on Current Trend in Physics and Photonics (ICCTPP-2022), a virtual conference was organized by School of Physics, Dr. Vishwanath Karad MIT World Peace University- Pune, India in association with IOP Science Publishing from 9th June to 11th June 2022. The conference was Chaired by Dr. Sachin Kulkarni, Head, School of Physics, MITWPU Pune and Co-Chaired by Prof. Dr. Narendra Mathakari and Dr. Ajit Deore from School of Physics.The purpose of the conference was to bring together leading academic scientists, researchers, industry professionals to exchange and share their experiences and research results on all aspects of general Physics and in particular the emerging field of photonics. In General Physics, the focus was mainly on material science, nanoscience, computational physics and theoretical physics. In Photonics, the focus was primarily on Lasers, Nanophotonics, Green photonics, Solar Energy, Plasmonics and Nonlinear Optics.The three-day conference program was carefully structured to encourage mutual inspiration and fruitful debate among researchers. Well known experts across India and the world were associated with the conference for keynote addresses, plenary sessions and invited talks. In addition, high quality research was presented by academicians, industry professionals, and research scholars from leading institutions across India, UAE, South Korea, Republic of Korea, Thailand, Tunisia and Algeria through oral and poster sessions. Total Ten oral and poster sessions was scheduled with topics ranging from Photonics, Optics, Nano Science and Material Science.On the first day the conference lamp was ignited with the Keynote address of Prof. Jagadish Chennupati, Distinguished Professor and Head of Semiconductor Optoelectronics and Nanotechnology Group in the Research School of Physics, Australian National University, Australia and the Plenary Talk of Prof. Venu Gopal Achanta, Director of CSIR-National Physical Laboratory, India. Prof. Chennupati enlighten the attendees on ‘Semiconductor Nanostructures for Optoelectronics Applications’ and Prof. Achanta on ‘Nanophotonics’. During afternoon session Dr. Nayana Vaval, Scientist, NCL, Pune, India delivered her talk on ‘Study of temporary bound states’ and Dr. Almantas Pivrikas, Senior Lecturer, Murdoch University, Australia expressed his views on ‘opto-electronic devices, such as photovoltaic cells, light emitting diodes, field-effect transistors and sensors’.The second day started with the Plenary talk of Prof. Prashant Sonar, ARC Future Fellow and Professor in School of Chemistry and Physics and Centre for Material Science at Queensland University of Technology, (QUT), Australia on the topic ‘Novel Conjugated Functional Materials for Photonics, Electronics, and Sensing’. Afternoon session was two invited talks, one by Dr. K. V. Sreekanth, Scientist-II, IMRE, A-Star, Singapore on ‘Reconfigurable nanophotonics with chalcogenide phase change materials’ and another by Dr. Dmitry Vasilyev, Dept of Physics, Johannes Gutenberg-Universität Mainz, Germany on ‘Imaging Spin Detection in Microscopy and Spectroscopy’.List of ICCTPP-2022, Committee Members are available in this Pdf.

Single photon controlled steady state electron transport through a resonance DQD-Cavity system in a strong coupling regime

We perform theoretical calculations to study steady-state electron transport in a double quantum dot, DQD, coupled to a quantized cavity photon field both in resonance and off-resonance regimes considering weak and strong coupling. In the resonant strong coupling regime, photon exchanges between the energy states of the DQD and the cavity are found reflecting multiple Rabi-resonances. The electron occupation of the states and the transport current can be smoothly increased by tuning the cavity-environment coupling strength. Making the system off-resonant, but still in the strong coupling regime, the photon exchange is diminished and the electron occupation of the system and the transport current through it are prominent for high cavity-environment coupling strength. In the weak coupling regime between the DQD and the cavity, the system has almost the same response in the resonant and the off-resonant regimes at high values of the cavity-environment coupling strength.

Nonlinear photonics with metasurfaces

Nonlinear optics is a well-established field of research that traditionally relies on the interaction of light with macroscopic nonlinear media over distances significantly greater than the wavelength of light. However, the recently emerged field of optical metasurfaces provides a novel platform for studying nonlinear phenomena in planar geometries. Nonlinear optical metasurfaces introduce new functionalities to the field of nonlinear optics extending them beyond perturbative regimes of harmonic generation and parametric frequency conversion, being driven by mode-matching, resonances, and relaxed phase-matching conditions. Here we review the very recent advances in the rapidly developing field of nonlinear metasurface photonics, emphasizing multi-frequency and cascading effects, asymmetric and chiral frequency conversion, nonperturbative nonlinear regimes, and nonlinear quantum photonics, empowered by the physics of Mie resonances and optical bound states in the continuum.

Resummation of the α expansion for nonlinear pair production by an electron in a strong electromagnetic field

We show how to resum the Furry-picture $\ensuremath{\alpha}$ expansion in order to take quantum radiation reaction and spin transition into account in the nonlinear trident process in (pulsed) plane-wave background fields. The results are therefore nontrivial functions of both the background field strength, $eE$, and the coupling to the quantized photon field, $\ensuremath{\alpha}={e}^{2}/4\ensuremath{\pi}$. The effective expansion parameter, $T$, is $\ensuremath{\alpha}$ times $eE/m\ensuremath{\omega}\ensuremath{\gg}1$, which makes higher orders in $\ensuremath{\alpha}$ important. We show that they can change the sign of the spin-dependent part already at $T<1$, which will be experimentally accessible. We also present a new resummation method that essentially does to a convergent series what Borel-Pad\'e resummation does to an asymptotic series.

Predicting Fundamental Transverse Electric Mode of Slab Waveguide Based on Physics-Informed Neural Networks

Over the past few years, deep learning has proven to be an effective and fast tool in many areas, especially in the field of photonics. The design of integrated optical devices relies on optical waveguides which requires a reliable and fast methods for determining the waveguide’s characteristics before the fabrication process. In this work, the newly emerging paradigm of physics-informed neural networks (PINNs) is employed for analyzing and predicting the fundamental transverse electric (TE) mode and effective refractive index ( ) of a slab waveguide. PINNs is particularly useful as it is a data and mesh-free method, which solve the most critical problems of computational modeling which are the speed and computational hardware cost. The suggested model has a prediction accuracy of up to 99% and effective refractive index relative error ranges between 10-5 and 10-6. Model results are validated against finite difference time domain method using Lumerical software and variational method.

Single-Photon Source in a Topological Cavity.

The introduction of topological physics into the field of photonics has led to the development of photonic devices endowed with robustness against structural disorder. While a range of platforms have been successfully implemented demonstrating topological protection of light in the classical domain, the implementation of quantum light sources in photonic devices harnessing topologically nontrivial resonances is largely unexplored. Here, we demonstrate a single photon source based on a single semiconductor quantum dot coupled to a topologically nontrivial Su-Schrieffer-Heeger (SSH) cavity mode. We provide an in-depth study of Purcell enhancement for this topological quantum light source and demonstrate its emission of nonclassical light on demand. Our approach is a promising step toward the application of topological cavities in quantum photonics.