Photon Field Research Articles

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.

High-efficiency ultrathin metasurfaces with simultaneous control of complete phase, amplitude, and polarization.

Metasurfaces that can simultaneously manipulate both amplitude and phase have garnered interest and have promising applications owing to their strong beam-steering ability; however, achieving a high maximum transmission while covering the full phase shift remains challenging. This paper proposes a chiral-structured meta-atom composed of two external cross-polarized patches and an internal coupling structure. It enables the independent modulation of the phase, amplitude, and polarization at large incidence angles and ensures a high maximum transmission with a complete phase shift enabled by the two internal rotation structures. The transmission phase and amplitude can be independently controlled by adjusting the geometry and rotation angle of the meta-atoms. The performance and feasibility of the method were verified using an ultra-thin high-order Bessel beam generator sample with a thickness of 2 mm (about λ0/11 at 14 GHz). This design can meet arbitrary requirements for extreme beam steering and has broad application prospects in the fields of electromagnetism and photonics.

Camera-based radiotherapy dosimetry using dual-material 3D printed scintillator arrays.

To describe a methodology for the dual-material fused deposition modeling (FDM) 3D printing of plastic scintillator arrays, to characterize their light output under irradiation using an sCMOS camera, and to establish a methodology for the dosimetric calibration of planar array geometries. We have published an investigation into the fabrication and characterization of single element FDM printed scintillators intending to produce customizable dosimeters for radiation therapy applications. 1 This work builds on previous investigations by extending the concept to the production of a high-resolution (scintillating element size 3×3×3mm3 ) planar scintillator array. The array was fabricated using a BCN3D Epsilon W27 3D printer and composed of polylactic acid (PLA) filament and BCF-10 plastic scintillator. The array's response was initially characterized using a 20×20cm2 6 MV photon field with a source-to-surface (SSD) distance of 100cm and the beam incident on the top of the array. The light signals emitted under irradiation were imaged using 200ms exposures from a sCMOS camera positioned at the foot of the treatment couch (210cm from the array). The collected images were then processed using a purpose-built software to correct known optical artefacts and determine the light output for each scintillating element. The light output was then corrected for element sensitivity and calibrated to dose using Monte Carlo simulations of the array and irradiation geometry based on the array's digital 3D print model. To assess the accuracy of the array calibration both a 3D beam and a clinical VMAT plan were delivered. Dose measurements using the calibrated array were then compared to EBT3 GAFChromic film and OSLD measurements, as well as Monte Carlo simulations and TPS calculations. Our results establish the feasibility of dual-material 3D printing for the fabrication of custom plastic scintillator arrays. Assessment of the 3D printed scintillators response across each row of the array demonstrated a nonuniform response with an average percentage deviation from the mean of 2.1%±2.8%. This remains consistent with our previous work on individual 3D printed scintillators which showed an average difference of 2.3% and a maximum of 4.0% between identically printed scintillators.1 Array dose measurements performed following calibration indicate difficulty in differentiating the scintillator response from ambient background light contamination at low doses (<20-25cGy) and dose rates (≤100 MU/min). However, when analysis was restricted to exclude dose values less than 10% of the Monte Carlo simulated max dose the average absolute percentage dose difference between Monte Carlo simulation and array measurement was 5.3%±4.8% for the fixed beam delivery and 5.4%±5.2% for the VMAT delivery CONCLUSION: In this study, we developed and characterized a 3D printed array of plastic scintillators and demonstrated a methodology for the dosimetric calibration of a simple array geometry.

Nanometer-Thin Stacks of MXenes (Ti3C2Tx and Ta4C3Tx) for Applications as Nonlinear Photonic Devices

Two-dimensional (2D) carbides of transition metals, so called “MXenes”, maintain excellent optical properties and unique layer stacking form via hydrogen bonds in contrast to other low-dimensional materials. These promising features have attracted increasingly research interest in the field of ultrafast photonics. In this work, titanium carbide (Ti3C2Tx) and tantalum carbide (Ta4C3Tx), as two promising MXene materials for photonic applications, are experimentally synthesized by the ultrasound-assisted liquid phase exfoliation technique. The morphology of prepared few-layer Ti3C2Tx and Ta4C3Tx has been systematically characterized by transmission electron microscopy and X-ray diffraction analysis. Density functional theory is performed to obtain their electronic band structures, demonstrating metallic properties and verifying their optical absorption at 1 μm. Their tempting optical modulation properties for multi-gigahertz pulsed laser emission are demonstrated by using them as saturable absorbers in a waveguide laser cavity. Particularly, high-performance Q-switched mode-locked lasers with/without laser mirrors are realized based on the hybrid waveguide laser configuration, delivering 1 μm laser pulses with durations as short as 30 ps. The results presented in this work show the great potential of metallic MXenes and waveguide structures for applications in functional photonic devices.

Optimization of heterogeneously integrated InP-Si on-chip photonic components.

We demonstrate comprehensive numerical studies on a hybrid III-V/Si-based waveguide system, serving as a platform for efficient light coupling between an integrated III-V quantum dot emitter to an on-chip quantum photonic integrated circuit defined on a silicon substrate. We propose a platform consisting of a hybrid InP/Si waveguide and an InP-embedded InAs quantum dot, emitting at the telecom C-band near 1550 nm. The platform can be fabricated using existing semiconductor processing technologies. Our numerical studies reveal nearly 87% of the optical field transfer efficiency between geometrically-optimized InP/Si and Si waveguides, considering propagating field along a tapered geometry. The coupling efficiency of a directional dipole emission to the hybrid InP/Si waveguide is evaluated to ∼38%, which results in more than 33% of the total on-chip optical field transfer efficiency from the dipole to the Si waveguide. We also consider the off-chip outcoupling efficiency of the propagating photon field along the Si waveguide by examining the normal to the chip plane and in-plane outcoupling configurations. In the former case, the outcoupling amounts to ∼26% when using the circular Bragg grating outcoupler design. In the latter case, the efficiency reaches up to 8%. Finally, we conclude that the conceptual device's performance is weakly susceptible to the transferred photon wavelength, offering a broadband operation within the 1.5-1.6 µm spectral range.

Ordered non-close packed colloidal array with morphology control.

Non-close packed (NCP) colloidal arrays find wide applications in the fields of photonics, optical chip fabrication, nano sphere lithography and so on. However, unlike their close packed counterparts, such arrays cannot be obtained by direct self-organization of colloidal particles and require specialized techniques involving plasma/reactive ion etching, electric field driven assembly, substrate stretching or precise positioning of the particles. In this article, we present a facile template guided approach for fabricating ordered NCP arrays of colloidal particles. First, we employ soft lithography to replicate self-assembled hexagonal close packed (HCP) arrays of 'larger colloidal particles' (LPs) to obtain a topographically patterned positive and/or negative replica of the initial array. These replicas are then used as templates to spin coat 'smaller colloidal particles' (SPs), which may even have some degree of poly-dispersity, to obtain ordered NCP arrays. We further show that pattern morphology can be modulated based on whether a single or a double replicated template is used to confine the SPs, the concentration (Cn) of the SPs in the casting solution as well as the relative commensuration of the diameter of the SPs (ds) with that of the LPs (dL). Finally, we show that such NCP arrays can be transferred onto any flat surface by UVO mediated colloidal transfer printing.

Solitonic Neural Network: A novel approach of Photonic Artificial Intelligence based on photorefractive solitonic waveguides

Neuromorphic models are proving capable of performing complex machine learning tasks, overcoming the structural limitations imposed by software systems and electronic neuromorphic models. Unlike computers, the brain uses a unified geometry whereby memory and computation occur in the same physical location. The neuromorphic approach tries to reproduce the functional blocks of biological neural networks. In the photonics field, one possible and efficient way is to use integrated circuits based on soliton waveguides, ie channels self-written by light. Thanks to the nonlinearity of some crystals, propagating light can write waveguides and then can modulate them according to the information it carries. Thus, the created structures are not static but they can self-modify by varying the input information pattern. These hardware systems show a neuroplasticity which is very close to the one which characterize the brain functioning. The solitonic neuromorphic paradigm this work introduces is based on X-junction solitonic neurons as the fundamental elements for complex neural networks. These solitonic units are able to learn information both in supervised and unsupervised ways by unbalancing the X-junction. The storage of information coincides with the evolution of structure that changes plastically. Thus, complex solitonic networks can store information as propagation trajectories and use them for reasoning.