Optical Communication Devices Research Articles

AC‐Driven Plasmon Waveguide Integrated Electroluminescent Device

AbstractPhotonic elements have greater information‐carrying capabilities compared to electronic components, making the development of high‐speed, chip‐integrated optical communication devices crucial for addressing interconnect bottlenecks in high‐speed computing systems. Significant progress has been made in studying light sources and their transmission. Despite these advancements, achieving a satisfactory integration of photonic circuits with both light source and optical waveguide functions has remained a challenge. Here, a silver nanowire (AgNW) waveguide‐integrated light source is demonstrated driven by alternating current (AC) voltage. AgNW functions as both the electrode and waveguide to simplify the device structure, and the 2D transition metal dichalcogenides (TMDs) monolayer acts as the gain media in device. The electroluminescence (EL) can be tunably modulated via adjusting the frequency and voltage of the AC in this device, and it is also successfully coupled into the waveguide with its transmission distance up to 25 µm. The experiments of electroluminescence and waveguide transmission of different materials and their interlayer excitons have made a preliminary exploration of multiple wavelength transmission. It provides a new research platform forward in the development of chip‐integrated optical communication devices, thereby hopefully addressing the interconnect bottleneck and unlocking the potential for enhanced performance and efficiency in high‐speed computing systems.

Design of high-efficiency InP/InGaAsP diluted waveguide for edge couplers

To transition integrated optical communication devices from laboratory settings to practical applications, efficient coupling between optical fibers and chip waveguides remains pivotal. This paper presents a systematic design of a diluted waveguide, a key component in the edge couplers of photonic integrated circuits. The primary purpose of the diluted waveguide lies in facilitating superior edge coupling with fiber waveguides, thereby seamlessly integrating external light sources into the waveguide structure. To commence, we employ the transfer matrix and effective refractive index techniques to simplify the 3-dimensional diluted waveguide into 2-dimensional multi-layer slab waveguides. By computing the field distribution of the fundamental mode within the diluted waveguide, the fiber-to-waveguide coupling efficiency can be derived using a simplified overlap equation and optimized diluted waveguide structure through particle swarm optimization algorithms. Consequently, we achieve a remarkable fiber-to-waveguide coupling efficiency exceeding 95% for TE-mode and 92% for TM-mode, with a polarization dependent loss (PDL) of merely 0.13 dB. Interestingly, the optimized diluted waveguide exhibits quasi-single mode behavior, as the fundamental mode containing 98% of the total energy propagates within it. Additionally, the diluted waveguide edge coupler demonstrates favorable alignment tolerance, with 1-dB excess losses of ±2.3 μm and (−2.5, +3) μm along the horizontal and vertical directions, respectively. Notably, our approach offers a versatile methodology for designing multi-layer waveguides across various materials. This method has the potential to be universally applied.

Second Harmonic Generation of Twisted Vector Vortex Beams Using aβ-BaB2O4 Crystal

In this study, we demonstrate both theoretically and experimentally second harmonic generation (SHG) of a twisted vector vortex optical field (TVVOF) using a nonlinear type-II phase-matched β-BaB2O4 (BBO) crystal. Our study introduces a novel method to manipulate SHG by independently modulating the two orthogonal polarization components of a TVVOF. This flexibility in controlling SHG can be achieved through accurate experimental adjustments of the polarization components. Furthermore, we reveal that the SHG can be dynamically tuned by varying the angle between the polarization direction of the optical field and the principal axis of the BBO crystal via rotation. These findings provide a new approach for the flexible manipulation of SHG in structured vector optical fields, which have potential applications in optical communication, quantum optics, and photonic device engineering.

A dynamic beam switching metasurface based on angular mode-hopping effect

Fast and versatile beam forming and steering technologies are now crucial for various emerging applications, including wireless optical communications and optical switches. However, these technologies often rely on expensive components, such as spatial light modulators (SLMs) and optical phase arrays (OPAs), which come with complex and power-consuming control systems. In response to this challenge, we propose a dynamic beam-switching method inspired by the mode-hopping effect of lasers. As a proof of concept, we introduce the dynamic beam switching metasurface (DBSM) design, featuring an in-plane mechanical actuation system. Our numerical analyses, based on the finite element method (FEM), demonstrate that the proposed DBSM exhibits versatile beam forming and steering functionalities. These include beam splitting and omnidirectional beam steering. Moreover, we anticipate that the tuning speed of the DBSM will reach the kilohertz (kHz) range or even higher when utilizing a microelectromechanical systems (MEMS) actuator, building upon pioneering research in this field. We envision it holds promising applications in areas such as light detection and ranging (LiDAR), optical wireless communication devices, and optical switches.

Near-Infrared Luminescent Materials Incorporating Rare Earth/Transition Metal Ions: From Materials to Applications.

The spotlight has shifted to near-infrared (NIR) luminescent materials emitting beyond 1000 nm, with growing interest due to their unique characteristics. The ability of NIR-II emission (1000-1700 nm) to penetrate deeply and transmit independently positions these NIR luminescent materials for applications in optical-communication devices, bioimaging, and photodetectors. The combination of rare earth metals/transition metals with a variety of matrix materials provides a new platform for creating new chemical and physical properties for materials science and device applications. In this review, the recent advancements in NIR emission activated by rare earth and transition metal ions are summarized and their role in applications spanning bioimaging, sensing, and optoelectronics is illustrated. It started with various synthesis techniques and explored how rare earths/transition metals can be skillfully incorporated into various matrixes, thereby endowing them with unique characteristics. The discussion to strategies of enhancing excitation absorption and emission efficiency, spotlighting innovations like dye sensitization and surface plasmon resonance effects is then extended. Subsequently, a significant focus is placed on functionalization strategies and their applications. Finally, a comprehensive analysis of the challenges and proposed strategies for rare earth/transition metal ion-doped near-infrared luminescent materials, summarizing the insights of each section is provided.

Continuous-variable quantum key distribution over 28.6 km fiber with an integrated silicon photonic receiver chip

Quantum key distribution, which ensures information-theoretically secret key generation, is currently advancing through photonic integration to achieve high performance, cost reduction, and compact size, thereby facilitating the large-scale deployment. Continuous-variable quantum key distribution is an attractive approach for photonic integrations due to its compatibility with off-the-shelf optical communication devices. However, its chip-based systems have encountered significant limitations primarily related to the shot-noise-limited receiver design, which demands low noise, wide bandwidth, high clearance, and well stability. Here, we report the implementation of a real local oscillator continuous-variable quantum key distribution system with an integrated silicon photonic receiver chip. Thanks to the well-designed chip-based homodyne detectors with a bandwidth up to 1.5 GHz and a clearance up to 7.42 dB, the transmission distance of the system has been extended to 28.6 km, achieving a secret key generation rate of Mbps level. This technological advancement enables the quantum key distribution systems with photonic integrated receivers to achieve the coverage in both access network scenarios and short-distance metropolitan interconnections, paving the way for the development of the next-generation quantum key distribution networks on a large scale.

Magneto-chiral Nonlinear Optical Effect with Large Anisotropic Response in Two-Dimensional Halide Perovskite.

The chiral organic-inorganic halide perovskites (OIHPs) are vital candidates for superior nonlinear optical (NLO) effects associated with circularly polarized (CP) light. NLO in chiral materials often couples with magnetic dipole (MD) transition, as well as the conventional electric dipole (ED) transition. However, the importance of MD transition in NLO process of chiral OIHPs has not yet been well recognized. Here, the circular polarized probe analysis of second harmonic generation circular dichroism (SHG-CD) provides the direct evidence that the contribution of MD leads to a large anisotropic response to CP lights in chiral OIHPs, (R-/S-MBACl)2PbI4. The thin films exhibit great sensitivity to CP lights over a wide wavelength range, and the g-value reaches up to 1.57 at the wavelength where the contribution of MD is maximized. Furthermore, it is also effective as CP light generator, outputting CP-SHG with maximum g-factor of 1.76 upon the stimulation of linearly polarized light. This study deepens the understanding of relation between chirality and magneto-optical effect, and such an efficient discrimination and generation of CP light signal is highly applicable for chirality-based sensor and optical communication devices.

Highly stable power control for chip-based continuous-variable quantum key distribution system.

Quantum key distribution allows secret key generation with information theoretical security. It can be realized with photonic integrated circuits to benefit the tiny footprints and the large-scale manufacturing capacity. Continuous-variable quantum key distribution is suitable for chip-based integration due to its compatibility with mature optical communication devices. However, the quantum signal power control compatible with the mature photonic integration process faces difficulties on stability, which limits the system performance and causes the overestimation of a secret key rate that opens practical security loopholes. Here, a highly stable chip-based quantum signal power control scheme based on a biased Mach-Zehnder interferometer structure is proposed, theoretically analyzed, and experimentally implemented with standard silicon photonic techniques. Simulations and experimental results show that the proposed scheme significantly improves the system stability, where the standard deviation of the secret key rate is suppressed by an order of magnitude compared with the system using traditional designs, showing a promising and practicable way to realize a highly stable continuous-variable quantum key distribution system on chip.

Metal Halide Perovskite Light-Emitting Devices for Optical Communications: A Spotlight on Speed, Brightness, Wavelength Tunability, Bidirectionality, and Integration

Metal Halide Perovskite Light-Emitting Devices for Optical Communications: A Spotlight on Speed, Brightness, Wavelength Tunability, Bidirectionality, and Integration

Exploring optical soliton solutions in highly dispersive couplers with parabolic law nonlinear refractive index using the extended auxiliary equation method

This study delves into the realm of optical soliton solutions within the intricate framework of highly dispersive couplers integrated with optical metamaterials featuring a parabolic law nonlinear refractive index. Employing the extended auxiliary equation method, the investigation systematically unveils various soliton solutions, including dark solitons, bright solitons, singular solitons, and a distinctive amalgamation of bright and singular solitons. The results illuminate the diverse dynamics of solitons in these complex systems, offering crucial insights into the interplay among dispersion, nonlinearity, and metamaterial characteristics. Beyond enhancing the theoretical understanding of soliton behavior in optical metamaterial couplers, the findings hold practical significance by potentially influencing the design and optimization of optical communication devices and systems.

Synthesis, optical, and spectroscopic studies of bismuth boro-tellurite glass system containing BaO and V2O5

A melt quenching technique was used for the preparation of xBaO–(30-x)TeO2–35Bi2O3–33B2O3–2V2O5 (5 ≤ x ≤ 25 mol%) glasses. The structural modifications are studied by X-ray diffraction, DSC, optical, infrared spectroscopy, and Raman as a function of BaO mol%. The progressive incorporation of BaO mol% in the BTBiBV glasses decreases the optical band gap values as the number of free electrons increases with the creation of additional NBOs. The FTIR spectra of the prepared glasses consist of BO3 trigonal and BO4 tetrahedral units while TeO2 changes to TeO3 andTeO4 structural units. The Raman spectra shows that the replacement of BaO with TeO2 decreases the concentration of Te–O–Te linkages within the volume of host glass, which increases the concentration of Ba–O–Te linkages along with BO3 units. Due to this, the overall glass formers connectivity decreases which intern to the creation of NBOs. Moreover, the research highlighted that BTBiBV-5 glasses have exceptional optical properties making them promising materials for photonics, optoelectronics, and optical communication device applications.

One- and two-dimensional electromagnetically induced gratings in a microwave-driven M-type atomic system

In this paper, we theoretically investigate a scheme for both 1D and 2D electromagnetically induced gratings (EIGs) in M-type atomic systems in which two ground states are coupled by a microwave field. It is observed that the presence of a microwave field enhances the probe diffraction efficiency to higher orders, thus leading to the construction of phase gratings in 1D and 2D cases. The study shows that changing the system parameters numerically, such as the strength of the applied microwave field, standing wave field, and the length of the atomic medium, leads to modulation of diffraction efficiency into higher orders. The application of microwave fields is a more convenient parameter for attaining increased first-order diffraction. We believe that the proposed system with a microwave field can be used for designing novel microwave sensing devices for optical networking and communication.

VO2/MoO3 Heterojunctions Artificial Optoelectronic Synapse Devices for Near-Infrared Optical Communication.

Artificial optoelectronic synapses (OES) have attracted extensive attention in brain-inspired information processing and neuromorphic computing. However, OES at near-infrared wavelengths have rarely been reported, seriously limiting the application in modern optical communication. Herein, high-performance near-infrared OES devices based on VO2/MoO3 heterojunctions are presented. The textured MoO3 films are deposited on the sputtered VO2 film by using the glancing-angle deposition technique to form a heterojunction device. Through tuning the oxygen defects in the VO2 film, the fabricated VO2/MoO3 heterojunction exhibits versatile electrical synaptic functions. Benefiting from the highly efficient light harvesting and the unique interface effect, the photonic synaptic characteristics, mainly including the short/long-term plasticity and learning experience behavior are successfully realized at the O (1342nm) and C (1550nm) optical communication wavebands. Moreover, a single OES device can output messages accurately by converting light signals of the Morse code to distinct synaptic currents. More importantly, a 3×3 artificial OES array is constructed to demonstrate the impressive image perceiving and learning capabilities. This work not only indicates the feasibility of defect and interface engineering in modulating the synaptic plasticity of OES devices, but also provides effective strategies to develop advanced artificial neuromorphic visual systems for next-generation optical communication systems.

Monolithic Electrically‐Driven Retroreflector Based on Gold Nanoparticles Embedded in Ferroelectric Polymer

The surface plasmon resonance (SPR) observed in metal nanostructures finds application in biosensing, optical communication technologies, and neuromorphic computing. There it enables the detection and transduction of dielectric environment changes in the vicinity of the metal nanostructure. Combining this principle with materials where the dielectric environment can be electrically modulated, it becomes possible to realize active optoelectronic plasmonic devices specifically designed for optical communication technologies. In this work, the use of an organic ferroelectric polymer to reversibly modulate the localized SPR (LSPR) of gold nanoparticles (AuNPs) inducing a reversible spectral shift of the resonance is investigated. The proposed plasmonic modulator is based on a two‐terminal device composed of AuNPs deposited on a transparent conductive electrode, covered by a ferroelectric polymer poly(vinylidene fluoride‐co‐trifluoroethylene) with a metallic electrode on top also serving as the mirror. By applying a voltage bias between the two electrodes, an electric field is generated within the device, enabling precise control over the dielectric environment of the AuNPs and thereby modulating the LSPR. It is demonstrated that this concept can be easily fabricated, potentially flexible, lightweight, and robust, making it an attractive choice for optical communication devices, particularly as a free space modulating retroreflector.

Multifrequency and Multimode Topological Waveguides in a Stampfli‐Triangle Photonic Crystal with Large Valley Chern Numbers

AbstractThe multifrequency quantum valley Hall effect (QVHE) has been realized to significantly improve the transmission capacity of topological waveguides, and the multimode QVHE with a large valley Chern number has been realized to increase the mode density of topological waveguides. However, multifrequency and multimode QVHEs have not been realized simultaneously. In this work, using tight‐binding model calculations and numerical simulations, a valley photonic crystal (VPC) consisting of a Stampfli‐triangle photonic crystal is constructed, and its multiple degeneracies in the low‐frequency and high‐frequency bands split simultaneously to realize the QVHE with multiple topological edge states (TESs). The multifrequency and multimode topological transmission with two low‐frequency modes and four high‐frequency modes is realized by means of simulations and experiments through a Z‐shaped waveguide constructed using two VPCs with opposite valley Chern numbers to prove the realization of a large valley Chern number in the two frequency bands. The two low‐frequency modes are successfully distinguished with position‐dependent selective excitations, which experimentally demonstrate the occurrence of a large valley Chern number. A frequency‐dependent multimode beam splitter is theoretically proposed for high‐performance integrated photonic device applications. These results provide new ideas for high‐efficiency and high‐capacity optical transmission and communication devices and their integration; furthermore, they broaden the application range of TESs.

Transmissible topological edge states based on Su–Schrieffer–Heeger photonic crystals with defect cavities

Abstract Topological photonic crystals have great potential in the application of on-chip integrated optical communication devices. Here, we successfully construct the on-chip transmissible topological edge states using one-dimensional Su–Schrieffer–Heeger (SSH) photonic crystals with defect cavities on silicon-on-insulator slab. Different coupling strengths between the lateral modes and diagonal modes in photonic crystal defect cavities are used to construct the SSH model. Furthermore, two photonic SSH-cavity configurations, called α and β configurations, are designed to demonstrate the topological edge states. Leveraging the capabilities of photonic crystal transverse electric modes with on-chip transmission, we introduced a waveguide to excite a boundary defect cavity and found that the transmission peak of light, corresponding to the topological edge state, can be received in another boundary defect cavity, which is caused by the tunnel effect. Moreover, the position of this peak experiences a blue shift as the defect cavity size increases. Therefore, by tuning the size of the SSH defect cavity, on-chip wavelength division multiplexing function can be achieved, which is demonstrated in experiments. The ultrafast response time of one operation can be less than 20 fs. This work harmonizes the simplicity of one-dimensional SSH model with the transmissibility of two-dimensional photonic crystals, realizing transmissible on-chip zero-dimensional topological edge states. Since transmission peaks are highly sensitive to defect cavity size, this configuration can also serve as a wavelength sensor and a reconfigurable optical device, which is of substantial practical value to on-chip applications of topological photonics.

Ultra-compact electro-optic phase modulator based on a lithium niobate topological slow light waveguide.

Electro-optic modulators (EOMs) are essential devices of optical communications and quantum computing systems. In particular, ultra-compact EOMs are necessary for highly integrated photonic chips. Thin film lithium niobate materials are a promising platform for designing highly efficient EOMs. However, EOMs based on conventional waveguide structures are at a millimeter scale and challenging to scale down further, greatly hindering the capability of on-chip integration. Here, we design an EOM based on lithium niobate valley photonic crystal (VPC) structures for the first time. Due to the high effective refractive index introduced by the strong slow light effect, the EOM can achieve an ultra-compact size of 4 μm×14 μm with a half-wave voltage of 1.4 V. The EOM has a high transmittance of 0.87 in the 1068 nm because of the unique spin-valley locking effect in VPC structures. The design is fully compatible with current nanofabrication technology and immune to fabrication defects. Therefore, it opens a new possibility in designing lithium niobate electro-optic modulators and will find broad applications in optical communication and quantum photonic devices.

System design study of a VLEO satellite platform using the IRS RF helicon-based plasma thruster

To achieve a feasible lifetime of several years, most satellites are deployed in orbits higher than 400 km. Drag of residual atmosphere causes a slow orbit decay, resulting in the deorbit of the spacecraft. However, e.g. optical instruments or communication devices would significantly benefit from lower altitudes in the range of 150–250 km. A solution to achieve this could be the application of atmosphere-breathing electric propulsion (ABEP), where the residual atmosphere is used to generate continuous thrust that compensates the drag.Within the EU-funded DISCOVERER project, the Institute of Space Systems (IRS) developed an electrode-less RF Helicon-based Plasma Thruster (IPT) suitable for such applications. Ignition and preliminary discharge characterizations of the IPT have been carried out at IRS facilities, using argon, nitrogen and oxygen. To further characterize the plasma plume, a torsional pendulum has been designed to determine the (local) momentum flux in the plasma jet, as well as a three-axis magnetic B-dot probe to carry out time-varying magnetic field measurements. Various intake designs were investigated, opening the possibility to conduct studies on potential satellite platforms within the frame of the ESA-funded project RAM-CLEP.A design study for an Earth Observation and Telecommunication satellite operating at 150–250 km with an extended mission lifetime is currently being carried out. The first system assessment focused on the comparison of different spacecraft configurations (“slender body” and “flat body”) and intake designs (specular or diffuse) with regard to overall drag and ABEP performance requirements.In this contribution, the design approaches for the current thruster and the diagnostic methods are depicted. Moreover, the current status of the system assessment is presented. Upcoming experimental studies of the ABEP system e.g. within the ESA-project RAM-CLEP and additional activities planned on system assessment are outlined.

Generation of Orbital Angular Momentum Light by Patterning Azopolymer Thin Films

Orbital angular momentum (OAM) encoding is a promising technique to boost data transmission capacity in optical communications. Most recently, azobenzene films have gained attention as a versatile tool for creating and altering OAM-carrying beams. Unique features of azobenzene films make it possible to control molecular alignment through light-induced isomerization about the azo bond. This feature enables the fabrication of diffractive optical devices such as spiral phase plates and holograms by accurately imprinting a phase profile on the incident light. By forming azobenzene sheets into diffractive optical elements, such as spiral phase plates, one can selectively create OAM-carrying beams. Due to the helical wavefront and phase variation shown by these beams, multiple distinct channels can be encoded within a single optical beam. This can significantly increase the data transmission capacity of optical communication systems with this OAM multiplexing technique. Additionally, holographic optical components made from azobenzene films can be used to build and reconstruct intricate wavefronts. It is possible to create OAM-based holograms by imprinting holographic designs on azobenzene films, which makes it simpler to control and shape optical beams for specific communication requirements. In addition, azobenzene-based materials can then be suitable for integration into optical communication devices because of their reconfigurability, compactness, and infrastructure compatibility, which are the main future perspectives for achieving OAM-based technologies for the next generation, among other factors. In this paper, we see the possible use of azobenzene films in the generation and modification of OAM beams for optical communications through light-induced isomerization. In addition, the potential role of azobenzene films in the development of novel OAM-based devices that paves the way for the realization of high-capacity, OAM-enabled optical communication networks are discussed.

Development of a quasi-ring airy vortex beam using an all-dielectric geometric phase metasurface

The quasi-ring Airy vortex beam (QRAVB) is a special type of vortex beam was recently proposed, which performs efficiently in turbulent environments. However, bulky optical elements, such as the spatial light modulator, used for generating the QRAVB hinder its application in modern integrated optical communication devices. Here, we present a type of compact optical element developed for generating the QRAVB by using an all-dielectric geometric phase metasurface. We simulate the performance of the designed metasurface and discuss several properties, such as autofocusing and self-healing of the metasurface-generated beams, are similar to Airy beams. This type of metasurface has potential applications in integrated free-space optical communication and on-chip optical information processing in the future.