Hasil untuk "Applied optics. Photonics"

D. Moss, R. Morandotti, A. Gaeta et al.

Yuyao Chen, Lu Lu, G. Karniadakis et al.

In this paper, we employ the emerging paradigm of physics-informed neural networks (PINNs) for the solution of representative inverse scattering problems in photonic metamaterials and nano-optics technologies. In particular, we successfully apply mesh-free PINNs to the difficult task of retrieving the effective permittivity parameters of a number of finite-size scattering systems that involve many interacting nanostructures as well as multi-component nanoparticles. Our methodology is fully validated by numerical simulations based on the finite element method (FEM). The development of physics-informed deep learning techniques for inverse scattering can enable the design of novel functional nanostructures and significantly broaden the design space of metamaterials by naturally accounting for radiation and finite-size effects beyond the limitations of traditional effective medium theories.

B. Jalali, S. Fathpour

Fang Li

The transient dynamics of electromagnetically induced transparency (EIT) are fundamental to understanding coherent light–atom interactions and the advancement of quantum technologies such as optical switching and quantum memory. However, in room-temperature atomic vapors, Doppler broadening significantly alters these dynamics, yet a comprehensive understanding of its impact on the transient EIT response remains lacking. In this study, we combine analytical and numerical methods to investigate the absorption dynamics of a weak probe field in a three-level Λ-type system driven by a strong coupling field, based on the optical Bloch equations and Laplace transform techniques. Our results show that the transient response is highly sensitive to both the atomic spontaneous emission rate and the Rabi frequency of the coupling field. Increasing the coupling field intensity not only accelerates the approach to steady state but also induces oscillatory dynamics and negative absorption. Under Doppler broadening, the time required to reach steady state increases by approximately three orders of magnitude compared to the Doppler-free case—an effect that is surprisingly insensitive to temperature variations across the 100–400 K range. Moreover, restoring a short steady-state time under broadened conditions necessitates increasing the coupling laser intensity by two orders of magnitude. These findings provide key insights into the influence of Doppler broadening on coherent transient processes and offer practical guidelines for the design of room-temperature atomic devices, including quantum memories and optical modulators.

Runnan Yu, Miaoning Ou, Qirui Hou et al.

Carbon dots (CDs) have shown great potential for application in optoelectronics, owing to their merits of tunable fluorescence, biocompatibility, low toxicity, and solution processability. However, the intrinsic nature of CDs makes them prone to fluorescence quenching in the aggregated state. In addition, the emission peak width at half maximum of a single CD is usually greater than 60 nm, and the emission spectra may exhibit a multi-peak superposition state, resulting in poor monochromaticity. Further, the unsatisfactory quantum yield of CDs restricts their further application. Considering this, doping strategies have successfully improved the electrical, optical, and chemical properties of CDs. The intrinsic structure and electron distribution of CDs can be effectively adjusted by metal or nonmetal doping. Doping atoms generate n- or p-type charge carriers, changing the bandgap energy, and thereby improving the photophysical properties of the CDs. In this comprehensive review, we explore the intricate effects of various doping strategies on CDs and systematically categorize them. Notably, we elaborate on the diverse types of doped CDs and emphasize their photophysical properties, aiming to elucidate the fundamental mechanisms underlying the influence of doping on CD performance. Specifically, this review describes the extensive applications of doped carbon dots (X-CDs) in optoelectronic devices, information encryption, anti-counterfeiting measures, imaging techniques, and detection fields, to spur further X-CD exploration and application.

Shichang Xu, Guohui Yuan, Hongwei Zhang et al.

The frequency linearity of a frequency-swept light signal is critical for ensuring the precision of Frequency-Modulated Continuous-Wave (FMCW) laser ranging systems. A two-stage nonlinearity correction mechanism for frequency-swept light is proposed, combining both data-driven and principle-based approaches. In the main correction stage utilizing an electro-optic phase-locked loop (EO-PLL), high temporal resolution phase detection is achieved. To address the failure of the EO-PLL caused by a bandwidth limitation of the digital loop filter (DLF), a novel pre-correction mechanism is developed based on a data-driven approach. In this mechanism, the neural network (NN) model establishes a mapping relationship between the input and output of the real laser-modulation system, which effectively simulates this physical system and avoids the risk of trial-and-error damage. Afterwards, the Soft Actor–Critic (SAC) model interacts with the NN model and trains a decision-making agent to determine the optimal modulation strategy for the nonlinearity pre-correction of the frequency-swept light. During the training process of the SAC agent, both the modulation strategy and the accuracy of evaluating the strategy’s effectiveness are optimized. Moreover, in contrast to the basic Actor–Critic model, the SAC model enhances the exploration of modulation possibilities by maximizing entropy expectation of random strategy, thereby improving the robustness of the pre-correction mechanism. Finally, the frequency-swept characteristic analysis experiment proves that integrating NN-SAC with EO-PLL enables frequency locking under the reduced bandwidth of the DLF. Additionally, through actual ranging experiments, it is also demonstrated that the proposed mechanism significantly enhances ranging precision, repeatability, and stability. Therefore, by integrating data-driven and principle-based approaches, this investigation offers an innovative perspective for the nonlinearity correction of FMCW laser ranging and, furthermore, electro-optic control scenarios.

Xueyue Zhang, Qi-Tao Cao, Zhuo Wang et al.

Ghada Hassanein, O. Alhaddad, M. Ellabban

Purpose: In this work, we mix two simple nematic liquid crystals (NLCs) and investigated the binaryNLCs mixtures of 7CB/PCH5 of different mixing ratios. Methodology: The pure liquid crystals 7CB and PCH5 and binary mixtures of them of high temperature stability were thermally analyzed by differential scanning calorimetry. The mixture 7CB/PCH5:30/70 wt% has the highest thermal stability with a nematic-isotropic (N-I) transition temperature at 50oC. The electrooptic properties of 7CB, PCH5, and the mixture 7CB/PCH5:30/70 wt% at room temperature were also investigated using an amplitude modulated electric signal (1 kHz - 100 Hz) by increasing diving peak voltage from 0 V to 10 V. The threshold volage is relatively reduced for the binary mixture in comparison to that value for PCH5. In comparison to the pure LCs,  the mixture 7CB/PCH5:30/70 wt% has the fastest response times of values 2.36 ms total time response, 0.41 ms rise time, and 1.95 ms fall time.  It has also the highest contrast ratio.  Moreover, it has a maximum measured transmission that is higher than those for PCH5 and 7CB by about 17 % and 8%, respectively, at a field strength of 2V/mm. Findings: The obtained results indicate that the electrooptic properties of PCH5 was improved when mixed with a proper ratio of 7CB, of  lower cost, more stablity , and higher potential for photonic applications. Unique Contriburibution to Theory, Practice and Policy: This expermental study shows that simply  by mixing two relatively low cost NLCs materials, one of high thermal stability  and low electro-optic properties with other one of low thermal stability and better electro-optic properties; this would improve the stability, response, and transmition of the binary mixture. If the a suitable driving method is applied, without doping with other orgnic or inorganic matrial.

David Coenen, Minkyu Kim, Herman Oprins et al.

The use of integrated heaters is widespread in silicon photonics for waveguide temperature control. The dynamical behavior of the heaters is important for determining their usefulness for certain applications. There exists ambiguity in the literature when it comes to reporting the thermo-optic time constants of Si photonic devices. Many studies report devices with different heating and cooling times without providing an explanation to this phenomenon. In this paper, a comprehensive theoretical framework is developed for interpreting experimental results. This framework is developed for interferometric devices (Mach–Zehnder-based) and resonant devices (rings). With this framework, the impact of measurement conditions on the obtained thermo-optic time constant can be simulated, and we provide an explanation to the observed difference between heating and cooling time constants. We also provide guidelines on how to disentangle optical non-linearities from the pure thermal response, which should be useful in for future reporting of thermo-optic time constants.

Pierre Koleják, Geoffrey Lezier, Daniel Vala et al.

Optically pumped spintronic terahertz emitters (STEs) have, in less than a decade, strongly impacted terahertz (THz) source technology, by the combination of their Fourier‐limited ultrafast response, their phononless emission spectrum and their wavelength‐independent operation. However, the intrinsic strength of the inverse spin Hall effect governing these devices introduces a challenge: the optical‐to‐terahertz conversion efficiency is considerably lower than traditional sources. It is therefore primordial to maximize at least their electromagnetic efficiency independently of the spin dynamics at play. Using a rigorous time‐domain treatment of the electromagnetic generation and extraction processes, an optimized design is presented and experimentally confirmed. With respect to the strongest reported spintronic THz emitters it achieves a 250% enhancement of the emitted THz field and therefore an 8 dB increase of emitted power. This experimental achievement brings STE close to the symbolic barrier of mW levels. The design strategy is generically applicable to any kind of ultrafast spin‐to‐charge conversion (S2C) system. On a broader level, our work highlights how a rigorous handling of the purely electromagnetic aspects of THz spintronic devices can uncover overlooked aspects of their operation and lead to substantial improvements.

A. Ryabchun, A. Bobrovsky

Modern optics and photonics constantly require break‐through materials and designs in order to achieve miniature, lightweight, highly tunable, and effective optical devices. One of the basic optical components is the diffraction grating (DG), widely used for the dispersion of light, beam steering, etc. This review gathers research efforts on diffractive optical elements based on cholesteric liquid crystal (CLC) materials with a supramolecular helical architecture. All main types and fabrication approaches of periodic diffractive structures from CLCs are classified and described. Key optical properties of DGs, their advantages and drawbacks are considered. Special attention is paid on the tunability of DGs including design principles and prospective chiral materials. The review consists of three parts divided according to the formation mechanism of diffractive structures: i) the spontaneously formed periodic structures from CLCs confined in cells with hybrid or homeotropic boundary conditions; ii) DGs generated by external electric field applied to CLCs layers; iii) light‐generated DGs (e.g., obtained by holography, mask exposure, photoalignment). The review also aims to initiate and gain collaborations between physicists, engineers and organic chemists to combine novel chiral photoswitches and molecular motors with sophisticated optical design paving the way towards novel smart optical materials.

I. Roumpos, Lorenzo De Marinis, M. Kirtas et al.

In this paper, we introduce optics-informed Neural Networks and demonstrate experimentally how they can improve performance of End-to-End deep learning models for IM/DD optical transmission links. Optics-informed or optics-inspired NNs are defined as the type of DL models that rely on linear and/or nonlinear building blocks whose mathematical description stems directly from the respective response of photonic devices, drawing their mathematical framework from neuromorphic photonic hardware developments and properly adapting their DL training algorithms. We investigate the application of an optics-inspired activation function that can be obtained by a semiconductor-based nonlinear optical module and is a variant of the logistic sigmoid, referred to as the Photonic Sigmoid, in End-to-End Deep Learning configurations for fiber communication links. Compared to state-of-the-art ReLU-based configurations used in End-to-End DL fiber link demonstrations, optics-informed models based on the Photonic Sigmoid show improved noise- and chromatic dispersion compensation properties in fiber-optic IM/DD links. An extensive simulation and experimental analysis revealed significant performance benefits for the Photonic Sigmoid NNs that can reach below BER HD FEC limit for fiber lengths up to 42 km, at an effective bit transmission rate of 48 Gb/s.

O. Andrew, S. N. Azmy, S. N. Azmy et al.

Landscape mapping is concerned with space planning whereby it emphasized space use in terms of function, mobility space, social space, and also ecological space. To plan this space design to reflect its purpose, initial data collection is critically needed. Depending on the site's characteristics such as hard and soft landscape features, collecting all of this data will be tedious and time-consuming. This research aims to employ Terrestrial Laser Scanning to iteratively approach landscape mapping and provide a landscape map architectural standard. In this research, by adapting Terrestrial Laser Scanning, a geomatic instrument that enables surveyors to immediately deliver accurate terrain relief mapping, technical structural assessments will be utilized to scan a diverse terrain, with a particular emphasis on hard and soft landscapes. The method of data acquisition for Terrestrial Laser Scanning was the traverse method, with that location-specific data will then be processed to generate a 3D point cloud model with georeferenced and transform it into 2D hard and soft landscape mapping. Then, a comparison will be made between the landscape map created from this research and the conventional landscape architecture approach. As a result of the data validation, it shows that Terrestrial Laser Scanning can provide high accuracy data in terms of northing, easting, and heights. Moreover, it can be concluded that there are numerous advantages to providing efficient information and an accurate representation of the site in a 3D model/point cloud, which enables landscape designers or architects to design a landscape map to their fullest potential in terms of creativity, landscape placement strategies, and as-built survey for maintenance updates. In addition, promote the development of more efficient landscape mapping techniques.

N. Panoiu, W. E. Sha, D. Lei et al.

Although a relatively new area of nanoscience, nonlinear plasmonics has become a fertile ground for the development and testing of new ideas pertaining to light–matter interaction under intense field conditions, ideas that have found a multitude of applications in surface science, active photonic nanodevices, near-field optical microscopy, and nonlinear integrated photonics. In this review, we survey the latest developments in nonlinear plasmonics in three-dimensional (metallic) and two-dimensional (graphene) nanostructures and offer an outlook on future developments in this field of research. In particular, we discuss the main theoretical concepts, experimental methods, and computational tools that are used together in modern nonlinear plasmonics to explore in an integrated manner nonlinear optical properties of metallic and graphene based nanostructures.

Fei Ge, Xiaoyan Han, Jialiang Xu

Strong coupling is a distinct light–matter interaction regime, in which the interaction is manifested in coherent oscillations of energy between matter and a photonic subsystem. The consequence of such a strong coupling is the adjustment of the energy states of molecules and materials, which can bring about fascinating chemical and physical properties, and therefore result in advanced applications in many fields such as Bose–Einstein condensation and coherent emission, polariton lasing, superfluidity, quantum information processing, Raman scattering, chemical landscape, etc. Recently, strong coupling has also demonstrated profound impacts on the nonlinear optical (NLO) properties of molecular materials. In this review, the recent research progress in the field of strongly coupled systems for NLO applications is summarized. The underlying concepts and the detailed features of strongly coupled molecular systems are introduced, and the NLO characteristics of strongly coupled systems are reviewed. Finally, an outlook of future directions for this emerging field is given.

G. Herriot, B. Carlson, T. Gunaratne et al.

For high contrast imaging, atmospheric turbulence may be sensed and corrected at very high band-width without Wavefront Sensors (WFS) or deformable mirrors using phase correcting integrated photonics devices and advanced signal processing. The overall system employs radio astronomy techniques developed for clock distribution, to sense and correct phase, and radio interferometry procedures to produce high resolution images. One of the tallest poles in high-contrast AO is the frame rate. Our simulation models estimate correction band-width can be 1-2 orders of magnitude faster than current high contrast Adaptive Optics (AO). The method employs a satellite loitering near a science object to send a coded reference laser to the telescope. We have designed and measured a 32 channel astrophotonics phase sensing and correcting device, which is low-cost and compact due to its telecommunications heritage. We are developing a prototype AO system to test the concept, first on a bench and then using a telescope pointed at sources on a tower. This paper also describes how the scheme may be extended to arrays of optical telescopes to give unprecedented micro-arcsecond resolution in the near infrared to obtain image and spectral data cubes of extrasolar planets. The method is also useful for satellite communications, and we have applied for a patent for both astronomy and communications.

Aniqa Zulfiqar, J. Ahmad

Abstract The current article explores the new optical solutions of the conformable fractional perturbed Gerdjikov-Ivanov (pGI) equation. The tanh method and the tanh-coth method have been applied for obtaining new solitary wave solutions. As a result, many previously known results of the conformable fractional pGI equation can be recovered by applying some appropriate choices of the arbitrary functions and arbitrary constants. This equation has several applications in photonic crystal fibers and also shows a momentous role in nonlinear fiber optics. The attained solutions address the diverse type of optical solutions in the form of 3D-plots, contour plots, and 2D-plots, specifying the free parameters accompanied by mandatory limitations to the confirm existence of such optical soliton solutions and to understand the dynamic behavior of these solutions. The obtained results reconfirm the worth and effectiveness of the used methods and are attractive for researchers for understanding the complexity of the considered model.

John Canning, Yunlong Guo, Zenon Chaczko

To address climate change, environmental monitoring and wellness more generally on a global scale, a new concept is presented - the bionic internet-of-things, or b-IoT. We propose the utilization of existing organic “sensor” technology that nature has provided and discuss a future adapting these to an existing inorganic internet to truly open up a global IoT. The use of organisms, in the first instance plants, bring an additional physical and psychological factor, connecting up living in things in a way that is consistent with natural symbiosis but extended over a global and potentially galactic scale. These plants not only monitor the environment, they interact to enable it to thrive, producing an ecosystem that consumes CO2, generates oxygen, recycling land and providing an environment for other organic species to develop. In contemporary real estate development, the need for a more whole ecosystem approach is recognized and that technology plays a vital role towards that. Thus, we identify wellness and wellbeing as an integral part of all future technology development. A fundamental challenge is connecting such sensors to the IoT. We briefly review technologies of relevance in the context of material, health and environmental considerations, and discuss novel transducer mechanisms. To assess sensor capability, we review our recent work on measuring leaf material properties using contact angle mapping, demonstrating a diversity of potential for environmental monitoring from this method alone. We also review some examples of common botanical properties that already exist which can in principle be readily coupled to existing transducers to create the hybrid b-IoT. We briefly speculate into the future of materials at the sensor end and into reaching space that can meet low cost and provide advanced functionality to help connectivity and integrate fibre and fibreless technologies.

Xiaocong Yuan, A. Zayats, Weibiao Chen

Since its first issue launched in January of 2019, Advanced Photonics has been a new member in the global optics and photonics family for more than three years. Advanced Photonics received its first Impact Factor of 13.582 in June this year and is ranked in the top 5 in the Optics and Photonics journal category. This successful experience encouraged us to consider a broader publication strategy in order to better serve the global optics and photonics community. We are very pleased to introduce a second member of our journal family, Advanced Photonics Nexus, which launches this month. In this inaugural issue, we feature one review article and five original articles covering fast-developing fields of modern optics and photonics. The review article focuses on deep learning spatial phase unwrapping and provides a detailed comparison of these deep-learningbased methods and traditional methods in the same context. Since Allen et al. demonstrated 30 years ago that beams with helical wavefronts carry orbital angular momentum (OAM), research on OAM has blossomed. We feature two research articles on OAM. Fu et al. present the OAM comb generation from azimuthal binary phases, a simple approach that opens new prospects for OAM spectrum manipulation and paves the way for many applications. Yang et al. present multiwavelength high-order optical vortex detection and demultiplexing coding using a metasurface. Its realization with a metasurface enables the combined measurements of OAM, the radial index, and wavelength using a single optical component. The issue also features three research articles on nonlinear, quantum, and integrated photonics. Liu et al. present an ultra-broadband and low-loss edge coupler for highly efficient second harmonic generation in thin-film lithium niobate and demonstrate greatly reduced power consumption in nonlinear frequency conversion. Wang et al. show the deterministic generation of large-scale hyperentanglement in three degrees of freedom. Such large-scale continuous variable superentanglement is deterministically generated experimentally for the first time, and the quantum entanglement capacity in continuous variable system is greatly improved. McGarvey and Bianucci present the general treatment of dielectric perturbations in optical rings; a formalism is introduced to describe the resonances in optical ring resonators subjected to a perturbation in their dielectric profile. Not only is this invaluable information for practical implementation of integrated photonics devices where fabrication inhomogeneities are always present, but also this formalism provides interesting insights on the effect of general perturbations. Advanced Photonics Nexus is designed as a Gold Open Access journal that publishes novel results of high significance and broad interest in all areas of optics and photonics. It publishes high-quality original papers, letters, and review articles, reflecting important advances in fundamental and applied aspects of optics and photonics. The most common inquiry raised by the community in the past months is what differentiates Advanced Photonics and Advanced Photonics Nexus. This is really an important question we discussed in depth before launching this new journal. We believe that both journals should publish only novel results of high significance and broad interest. With Advanced Photonics Nexus, we would like to provide the optics community an additional opportunity for fast-track publication of suitable articles which undergo strict peer-review, either directly submitted or transferred from its well-established sibling Advanced Photonics. On behalf of our eminent editorial board, we guarantee both paper quality for our readers and smooth publishing experience for our authors. We are looking forward to publishing your research.

Shaoliang Yu, Luigi Ranno, Qingyang Du et al.

Efficient fiber‐to‐chip coupling has been a major hurdle to cost‐effective packaging and scalable interconnections of photonic integrated circuits. Conventional photonic packaging methods relying on edge or grating coupling are constrained by high insertion losses, limited bandwidth density, narrow band operation, and sensitivity to misalignment. This work presents a new fiber‐to‐chip coupling scheme based on free‐form reflective micro‐optics. A design approach which simplifies the high‐dimensional free‐form optimization problem to as few as two full‐wave simulations is implemented to empower computationally efficient design of high‐performance free‐form reflectors while capitalizing on the expanded geometric degrees of freedom. This work demonstrates fiber array coupling to waveguides taped out through a standard foundry shuttle run and backend integrated with 3‐D printed micro‐optics. A low coupling loss down to 0.5 dB is experimentally measured at 1550 nm wavelength with a record 1‐dB bandwidth of 300 nm spanning O to U bands. The coupling scheme further affords large alignment tolerance, high bandwidth density, and solder reflow compatibility, qualifying it as a promising optical packaging solution for applications such as wavelength division multiplexing communications, broadband spectroscopic sensing, and nonlinear optical signal processing.