Communication Applications Research Articles

Selective amplification effect on the diffraction efficiency of a phase grating generated by femtosecond laser pulses.

A phase grating that selectively amplifies diffraction orders that are multiples of a determined integer is designed. For the proposed grating, multiples of the fourth order are enhanced. These results are supported by experiments. The structure is inscribed in the volume of a lithium niobate crystal by employing the femtosecond laser pulse micro-machining technique. A model based on the Raman-Nath behavior of the grating predicts a diffraction efficiency enhancement for those selected orders. Moreover, it is observed that by changing the incidence angle allows transferring energy from multiples of fourth orders to multiples of three. These findings have potential applications in optical spectroscopy and optical communications as well as for photonic devices in which a controlled energy exchange between orders is necessary. The basic wave nature of the mentioned effect allows finding a counterpart in different wavelength ranges of the electromagnetic spectrum.

Efficient generation of polarization-entangled photons in metal-organic framework waveguides

Parametric nonlinear optical processes are instrumental in optical quantum technology for generating entangled light. However, the range of materials conventionally used for producing entangled photons is limited. Metal-organic frameworks (MOFs) have emerged as a novel class of optical materials with customizable nonlinear properties and proven chemical and optical stability. The large number of combinations of metal atoms and organic ligand from which bulk MOF crystals are known to form, facilitates the search of promising candidates for nonlinear optics. To accelerate the discovery of next-generation quantum light sources, we employ a multi-scale modeling approach to study phase-matching conditions for collinear degenerate type-II spontaneous parametric down conversion (SPDC) with MOF-based one dimensional waveguides. Using periodic-density-functional theory calculations to compute the nonlinear optical properties of selected zinc-based MOF crystals, we predict polarization-entangled pair generation rates of order 104 − 107 s−1mW−1 at 1064 nm for 10 mm crystals, improving the brightness of industry materials such as PPKTP and BBO in some cases. This work underscores the great potential of MOF single crystals as entangled light sources for applications in quantum communication and sensing.

Adjusting Mood in Mandarin Chinese: A Game Theory Approach to Double and Redundant Negation with Entropy

Abstract This study investigates how Mandarin Chinese speakers use double and redundant negations to adjust information entropy and convey the speaker’s mood. Integrating Gricean implicature, signaling game theory, and information entropy, we quantified uncertainty in negation sentences by calculating self-information of negation markers and overall entropy for negations versus affirmatives. Analyzing sentences from the BCC Corpus of Mandarin Chinese newspapers, we extracted double and redundant negation patterns, calculated their frequencies, and compared entropy values in payoff matrices against affirmatives. Contextual analysis of surrounding discourse interpreted pragmatic functions. Our findings reveal that universal double negations reduce sentence entropy, intensifying assertiveness. Modal forms further decrease entropy, amplifying necessity, while conditional patterns strengthen the asserted conditions. Euphemistic double negations increase entropy, weaken assertiveness, and align with Levinson’s Manner Principle. This increase in entropy quantifies pragmatic markedness, allowing tentative critiques. Redundant negations significantly reduce entropy, strengthening negative attitudes. We elucidate how interlocutors navigate cooperative discourse by quantifying uncertainty via entropy measures, making contextually-optimal linguistic choices like assertion, indirectness, and emphasis. These findings impact signaling game theory and pragmatic markedness, with applications in natural language processing, cross-cultural communication, and computational models. Future research could explore other languages and cognitive and social factors in negation use.

Development and application prospect of photonic integrated circuits

Because the technical process is reaching its limits, the development of integrated circuits has entered the slow zone, which makes people gradually pay more attention to the new generation of integrated technologyphotonic integrated circuits (PIC). To give readers a general idea of PIC, this paper will first introduce the basic knowledge of photonic integrated circuits and compare photonic integrated circuits with traditional integrated circuits (IC) from different points of view, including their development history, properties, components, and potential. After that, some current technical innovations in optical communication, optical computing, and photonic quantum applications and development trends of photonic integrated circuits will be reviewed. Finally, three novel and promising technologies will be introduced to discuss how to solve the major challenge of improving integration. This work is not only a comprehensive and concise summary of the development of photonic integrated circuits so far but also an active exploration of solutions to the major challenges facing people in this field.

A novel modified complementary metamaterial resonator based dual-band bandpass quasi-elliptic filter using half-mode SIW cavity with wide stopband rejection for wireless communication applications

This article presents a novel dual-band metamaterial bandpass quasi-elliptic filter (DBBPF) for wireless communication applications, addressing the critical need for compact, high-performance multi-band filters in modern systems. The proposed filter leverages substrate-integrated waveguide cavity (SIWC) technology combined with innovative complementary metamaterial resonators to achieve significant miniaturization while maintaining excellent electrical performance. The filter’s design incorporates four complementary resonators of modified rectangular shape (CMSRR) on the metalized top face, generating targeted operating bands below the SIW cutoff frequency. To control their resonances, the size of each CMSRR is optimized for electrical dimensions of just 0.154 λ0× 0.115 λ0× 0.028 λ0. We present a comprehensive analysis of both full mode (FMSIWC) and half mode (HMSIWC) configurations, demonstrating dual-bandpass behavior with central frequencies at 5.79 and 9.82 GHz for FMSIWC, and 5.72 and 9.74 GHz for HMSIWC. The electromagnetic behavior of the basic cell of the filter is analyzed based on the frequency characteristics of its permittivity and permeability. A parametric study according to the location of the metamaterial resonators in the filter is conducted to have the optimized dimensions. Additionally, the confinement of the electric field in the two filter configurations is discussed to better understand their behavior. The fabricated HMSIWC filter, implemented on an FR4-Epoxy substrate measuring only 54.60 × 25.75 × 1.5875 mm3, achieves remarkable miniaturization while maintaining desired performance characteristics. Experimental results validate the simulated performance, demonstrating excellent agreement for both configurations. Key performance metrics include fractional bandwidths of 3.77 and 6.98 %, and insertion losses of 1.33 dB and 2.14 dB for the two passbands in the HMSIWC design. This work advances the state-of-the-art SIW filter design by combining half-mode techniques with optimized CMSRR structures, resulting in a compact, high-performance dual-band filter. The proposed DBBPF’s simple design and small form factor make it an ideal candidate for integration into various wireless communication systems, particularly where space constraints are critical.

Quantitative determination of fractional topological charge based on the rotational Doppler effect

The utilization of fractional-order vortex beams extends the diversity of optical field manipulation, permits for more flexible control over beam propagation, and provides novel applications in optical communications, edge enhancement imaging, and particle manipulation. However, compared with the integer-order vortex beams, the topological charge measurement techniques for fractional-order vortex beams are not well developed, impeding the further exploration of its applications. In this paper, the frequency signal of rotational Doppler effect and corresponding broadening behavior under the fractional-order vortex beam illumination were analyzed. When the fractional topological charge approaches a half integer, the broadening is minimized. Leveraging this relationship, we designed a phase-compensated scheme coupled with signal-to-noise ratio detection to realize the real-time fractional topological charge measurement. The single pixel photodetector was used and eliminated the need for two-dimensional image acquisition and analysis, ensuring efficient acquisition and quantitative analysis. Both theoretical and experimental results confirm the feasibility of this method, thereby advancing the comprehension of the optical Doppler effect and potentially paving the way for future investigations into fractional vortex beams.

Manipulating arbitrarily shaped Mathieu bottle beams based on geometric factor design

We demonstrate arbitrarily shaped Mathieu bottle beams (MBBs) based on geometric factor design. By elaborately selecting elliptical trajectory parameters and corresponding orders, the MBBs can be tailored to diverse longitudinal and transversal shapes simultaneously. The proposed method breaks through the limitation that the components of conventional bottle beams can only self-accelerate along paraxial paths with fixed shapes. Moreover, at both ends the MBBs exhibit ideally symmetric as well as abrupt autofocusing properties. The work presented in this paper would be of significance for the generation of optical bottle beams that are anticipated to find applications in optical manipulation and communication.

Supermode lasing and light amplification in multicore bismuth-doped fiber

Multicore fibers are promising structures with specific light propagation properties, which can be managed to benefit several applications in optical communications, fiber lasers and amplifiers, high-resolution imaging, and fiber-based sensors. The current use of multicore fibers in laser technology is mainly focused on in-phase coherent beam combining in far-field regions (out-cavity) using bulk optical elements. However, this approach is challenging in terms of the power scalability of all-fiber lasers (intra-cavity), particularly with using low-gain media, where it is needed to provide mode-coupling (supermode propagation) stability along relatively long lengths. Here, we report a conceptual design and fabrication of a multicore bismuth-doped fiber that is capable of achieving light amplification and stable lasing in the E-telecom band inside the cavity using the supermode selection approach. By analysis of experimental and simulation data, it was found that the employment of the proposed design of a Bi-doped fiber provides a considerable advantage over the single-core fiber in terms of laser performance (output power, slope efficiency) in the cladding-pumped configuration. These results open up new opportunities for further advancement of the optical fiber technology towards efficient bismuth-doped fiber-integrated amplifiers and lasers for the O+E+S+C+L+U-telecom bands, which may find important applications, especially for the development of next-generation multiband optical transmission systems.

Micro-transfer printed high-speed InP-based electro-absorption modulator on silicon-on-insulator

A high-speed InP-based electro-absorption modulator (EAM) on 220 nm silicon-on-insulator (SOI) is designed, fabricated, and measured. The III–V device is heterogeneously integrated to the SOI using transfer printing, with direct bonding. The printing accuracy of the device was within ±0.5 μm. This design evanescently couples light between the III–V waveguide and the SOI via a taper region in the InP ridge for high transmission. This method is a flexible and robust method of transferring an InP EAM to SOI, where multiple device variations have been transferred. At 1550 nm, the printed EAM has a measured electrical bandwidth of up to 40 GHz, an extinction ratio (ER) of 30 dB from 0 to −6 V, and an insertion loss of 6.5 dB, which reduces with longer wavelengths. An ER of 25 dB is obtained over a spectral bandwidth of 30 nm with biasing to −8 V. Open-eye diagrams were measured up to 50 Gbps in a back-to-back measurement. This device is suitable for applications in high-speed communications and sensing, leveraging the added advantage of III–V absorption modulation on a silicon photonics platform.

Polarization-insensitive multimode interference coupler on an x-cut thin-film lithium niobate platform.

Thin-film lithium niobate (TFLN) is a promising integrated photonics platform but currently lacks a polarization-insensitive multimode interference (MMI) coupler, a crucial component for polarization-related optical communication applications such as polarization management, polarization-division multiplexing, and polarization-insensitive modulation systems. This paper presents a novel, to the best of our knowledge, approach by rotating the MMI structure on an anisotropic x-cut TFLN at specific angles to compensate for the difference in the beat length between the two polarizations. A polarization-insensitive 1 × 2 MMI coupler is experimentally achieved with measured transmittances of -2.5 to -4 dB for both output ports and polarization modes in the wavelength range of 1520-1580 nm.

Stability analysis and soliton solutions of the (1+1)-dimensional nonlinear chiral Schrödinger equation in nuclear physics

The nonlinear Schrödinger equation equation is one of the most important physical models used in optical fiber theory to explain the transmission of an optical soliton. The field of chiral soliton propagation in nuclear physics is very interesting because of its numerous applications in communications and ultra-fast signal routing systems. The (1+1)-dimensional chiral dynamical structure that describes the soliton behaviour in data transmission is dealt with in this work using a variety of in-depth analytical techniques. This work has applications in particle physics, ionised science, nuclear physics, optics, and other applied mathematical sciences. We are able to develop a variety of solutions to demonstrate the behaviour of solitary wave structures, periodic soliton solutions, chiral soliton solutions, and bell-shaped soliton solutions with the use of applied techniques. Moreover, in order to verify the scientific calculations, the stability analysis for the observed solutions of the governing model is taken into consideration. In addition, the 3-dimensional, contour, and 2-dimensional visuals are supplied for a better understanding of the behaviour of the solutions. The employed strategies are dependable, uncomplicated, and effective; yet have not been utilised with the governing model in the literature that is now accessible. The resulting outcomes have impressive applications across a large number of study areas and computational physics phenomena representing real-world scenarios. The methods applied in this model are not utilized on the given models in previous literature so we can say that these describe the novelty of the work.

A framework for Gaussian Q approximation with BSA and its application to RIS-assisted systems

This paper proposes a novel and improved Chiani approximation for the Gaussian Q-function by employing the backtracking search optimization algorithm (BSA). The proposed approximation includes only exponential terms which are comfortable for the mathematical functionality. Then, a wireless communication application of reconfigurable intelligent surface (RIS) structures, which are anticipated to play a crucial role in integrated sensing and communication (ISAC), has been presented. In the considered wireless communication scenario, the link between the source and RIS node is Nakagami-m fading, while the link between RIS node and the destination is Rayleigh fading. The received probability density function (PDF) expression of instantaneous signal to noise ratio for this system has been derived analytically. Using this derived PDF, the error expression (Pe) for the RIS-assisted communication system employing the rectangular quadrature amplitude modulation (RQAM) technique has been obtained with the assistance of the proposed improved Chiani approximation in this study. The obtained RQAM error figures are presented comparatively, and the results clearly show that the Pe expression by obtained the proposed approximation with BSA for the RIS-assisted communication system, which is an important aspect for ISAC, is in excellent agreement with computer simulations.

Ultra-precise, sub-picometer tunable free spectral range in a parabolic microresonator induced by optical fiber bending.

Surface nanoscale axial photonic (SNAP) microresonators are fabricated on silica optical fibers, leveraging silica's outstanding material and mechanical properties. These properties allow for precise control over the microresonators' dimension, shape, and mode structure, a key feature for reconfigurable photonic circuits. Such circuits find applications in high-speed communications, optical computing, and optical frequency combs (OFCs). However, consistently producing SNAP microresonators with equally spaced eigenmodes has remained challenging. In this study, we introduce a method to induce a SNAP microresonator with a parabolic profile. We accomplish this by bending a silica optical fiber in a controlled manner using two linear stages. This approach achieves a uniform free spectral range (FSR) as narrow as 1 pm across more than 45 modes. We further demonstrate that the FSR of the SNAP microresonator can be continuously adjusted over a range nearly as wide as one FSR itself, specifically from 1.09 to 1.72 pm, with a precision of ±0.01 pm and high repeatability. Given its compact size and tuning capability, this SNAP microresonator is highly promising for various applications, including the generation of tunable low-repetition-rate OFC and delay lines.

Reprogrammable metasurface design for NIR beam steering and active filtering

Reprogrammable metasurfaces enable active modulation of light at subwavelength scales. Operating in the microwave, terahertz, and mid-infrared ranges, these metasurfaces find applications in communications, sensing, and imaging. Electrically tunable metasurfaces operating in the near-infrared (NIR) range are crucial for light detection and ranging (LiDAR) applications. Achieving a NIR reprogrammable metasurface requires individual gating of nano-antennas, emphasizing effective heat management to preserve device performance. To this end, here we propose an electrically tunable Au–vanadium dioxide (VO2) metasurface design on top of a one-dimensional Si–Al2O3 photonic crystal (PC), positioned on a SiC substrate. Each individual Au–VO2 nano-antenna is switched from an Off to ON state via Joule heating, enabling the programming of the metasurface using 1-bit (binary) control. While operating as a nearly perfect reflector at λ0=1.55μm , the materials, thickness, and number of the layers in the PC are carefully chosen to ensure it acts as a thermal metamaterial. Moreover, with high optical efficiency (R ∼ 40% at λ0 ), appropriate thermal performance, and feasibility, the metasurface also enables broadband programmable beam steering in the 1.4−1.7μm range for a wide steering angle range. This metasurface design also offers active control over NIR light transmittance, reflectance and absorptance in the wavelength range of 0.75−3μm . These characteristics render the device practical for LiDAR and active filtering.

A compact wideband low‐profile all textile on/off body antenna for Satcom and defense applications

SummaryA compact, flexible, low‐profile end‐fire broadband wearable antenna operating in Ku‐band /X‐band is proposed in this manuscript for defense and satellite communications (Satcom) applications. The main objective of this work is cross‐polarization reduction by the defected ground structure (DGS), which offers a wider bandwidth. Due to its flexibility and ability to absolutely conform to the curved‐shaped human body, denim fabric is used as a substrate, whereas copper tape is used as a conductor, which allows for the integration of the antenna into garments and makes it appropriate for a wide range of wearable applications in various bands. The prototype has been developed with a size of mm3 for experimental validation. The measured results from a fabricated prototype are well matched with the simulated ones of the proposed design, which indicate a wide bandwidth of 57.35% (7.76–14 GHz) appropriate for use in applications such as defense operating from 8 to 12 GHz, satellite TV (11.7–12.2 GHz), Ku‐band downlink (10.95–11.7 GHz), Ku‐band uplink (11.7–14.5 GHz), and a high gain of 5.1 dBi. The specific absorption rate (SAR) is much below the permissible limit of 1.6 W/kg, with better radiation characteristics. Thus, the proposed antenna is more compact, and it clearly achieves a smaller footprint, larger impedance bandwidths, and a low SAR with potential prospect for Satcom and defense purposes.

Dual-band inset-fed diamond-shaped patch MIMO antenna for wireless communication applications

A compact inset-fed rectangular-shaped multiple-input multiple-output (MIMO) patch antenna with a diamond-shaped slot is proposed for dual-band wireless communication applications. It comprises with two identical rectangular-shaped radiating elements. The proposed inset-fed diamond-shaped slot MIMO patch (IDSMP) antenna has overall dimensions is 20 × 40 × 1.6 mm3. To achieve low mutual coupling and good diversity performance, circular slots are etched on the ground plane and diamond slots are etched from the rectangular radiating patches. The edge-to-edge separation between the radiating elements is 4 mm. The IDSMP antenna is resonating at 8.2 GHz and 14.0 GHz frequencies and a gain of 5.63dBi and 5.43dBi respective operating frequency. It achieves the wider dual bandwidths of 400 MHz (8.00 GHz to 8.40 GHz) and 940 MHz (13.63 GHz to 14.57 GHz) of respective frequencies. The IDSMP antenna MIMO parameters are presented for the envelope correlation coefficient is < 0.0, diversity gain is > 9.9, channel capacity loss is < 0.1 bits/sec/Hz, mean effective gain is investigated (−4 dB < MEG < −7 dB), and total active reflection coefficient is also obtained. The simulated and experimentally attained values are presented, and it is showing fine agreement.

Controllable optical effects in Landau-quantized graphene

This paper investigates the manipulation and control of optical properties in a Y-configured four-level Landau-Quantized Graphene system. Through a comprehensive analysis of the density matrix elements, we explore the influence of various system parameters, including control field intensities, detunings, and decay rates, on the optical response of the graphene sample. Our findings unveil compelling phenomena such as optical transparency, sub- and superluminal light propagation, and the emergence of multiple absorption peaks and transparency windows. Specifically, we examine the impact of decay rates on the absorption characteristics of graphene, revealing that higher decay rates diminish the effectiveness of Electromagnetically Induced Transparency (EIT) and slow light in the system. Furthermore, by systematically varying system parameters, we demonstrate the controllability of achieving either single or double EIT through manipulation of control field intensities and detunings. These results open promising avenues for applications in optical communications and quantum information processing, where precise control over graphene's optical properties is critical.

A web experience exploring spatio–linguistic data: the case of place-making signs in Northern Sweden

ABSTRACT Previous research has highlighted the limitations encountered in representing the dynamism of language use and contacts. Here, linguistic landscapes from five towns in Northern Sweden are the point of departure for investigating novel perspectives through the geovisualization of multilingualism, with the ultimate aim of understanding how languages in our surroundings help construct public spaces. As an outcome, a web GIS application, based on 6865 thematically analyzed photographs, was developed as an interactive resource for visualizing and sharing the data and enabling new modes of analysis and new research questions. The article describes the data collection and curation processes, app development using GIS software and software-as-a-service, the eventual app design and interaction, and the update and maintenance plans, as well as discussing challenges and considerations related to temporalities, spatialities, and technicalities. The web GIS has potential applications in spatial analysis, research communication, and education.

Generation of dual vortices with controlled topological charges based on spin-decoupled moiré metalens

By their powerful talent in manipulating optical parameters, metasurfaces demonstrate great ability in the generation of the vortex beams. Until now, vortex beam generators constructed by metasurfaces mostly lack tunability, which reduces the scope of their applications. Here, spin-decoupled moiré metalenses composed of two cascaded all-dielectric metasurfaces are designed. Utilizing mathematical derivation and numerical simulation, dual vortices with variable topological charge can be generated under the incidence of orthogonal circularly polarized light by tuning the mutual rotation between the two cascaded metasurfaces. Meanwhile, vector vortex beams can be produced by superposition of dual focused vortices under the linearly polarized light illumination and whose vector polarized states can also be manipulated by mutual rotation. This work provides a flexible design strategy for continuous manipulation of singular beams, which have potential applications in optical communication, microparticle manipulation, and super-resolution imaging.

Atomic-level quantum well degradation of GaN-based laser diodes investigated by atom probe tomography

Gallium nitride (GaN)- based lasers are extensively employed in display, lighting, and communication applications due to their visible laser emission. Despite notable advancements in their performance and reliability, sustained device functionality over extended periods remains a challenge. Among the diverse mechanisms contributing to degradation, the deterioration of quantum wells poses a persistent obstacle. In this study, we investigated the atomic-level degradation of quantum wells within GaN-based laser diodes utilizing atom probe microscopy. Our analysis revealed a substantial increase in indium fluctuation, accompanied by the formation of indium protrusions at the quantum well interfaces, which provides a credible explanation for the observed increase in FWHM (full width at half maximum) of the spontaneous spectra of lasers following prolonged operation. Additionally, magnesium analysis yielded no evidence of diffusion into the quantum well region. Combined with prior studies, we attribute the degradation of quantum wells primarily to the formation of indium-related non-radiative recombination centers.