Optical Information Processing Research Articles

Unidirectional chiral scattering from single enantiomeric plasmonic nanoparticles

Controlling scattering and routing of chiral light at the nanoscale is important for optical information processing and imaging, quantum technologies as well as optical manipulation. Here, we introduce a concept of rotating chiral dipoles in order to achieve unidirectional chiral scattering. Implementing this concept by engineering multipole excitations in helicoidal plasmonic nanoparticles, we experimentally demonstrate enantio-sensitive and highly-directional forward scattering of circularly polarised light. The intensity of this highly-directional scattering is defined by the mutual relation between the handedness of the incident light and the chirality of the structure. The concept of rotating chiral dipoles offers numerous opportunities for engineering scattering from chiral nanostructures and optical nano-antennas paving the way for innovative designs and applications of chiral light-matter interactions.

All-optical analog differential operation and information processing empowered by meta-devices

Abstract The burgeoning demand for high-performance computing, robust data processing, and rapid growth of big data necessitates the emergence of novel optical devices to efficiently execute demanding computational processes. The field of meta-devices, such as metamaterial or metasurface, has experienced unprecedented growth over the past two decades. By manipulating the amplitude, phase, polarization, and dispersion of light wavefronts in spatial, spectral, and temporal domains, viable solutions for the implementation of all-optical analog computation and information processing have been provided. In this review, we summarize the latest developments and emerging trends of computational meta-devices as innovative platforms for spatial optical analog differentiators and information processing. Based on the general concepts of spatial Fourier transform and Green’s function, we analyze the physical mechanisms of meta-devices in the application of amplitude differentiation, phase differentiation, and temporal differentiation and summarize their applications in image edge detection, image edge enhancement, and beam shaping. Finally, we explore the current challenges and potential solutions in optical analog differentiators and provide perspectives on future research directions and possible developments.

Low‐Power Optoelectronic Synaptic Transistors with Multimodal Neuromorphic Computation and Retinal‐Inspired Multiband Optical Binary Communication

Biomimetic neuromorphic optoelectronics exude tempting attraction in multimodal interaction and visual applications because of their capability of integrating sensing, memorizing, and processing in a single device. Herein, a natural dextran film that is intrinsically green and transparent is employed as the dielectric of the optoelectronic synaptic transistors (OSTs). The resulting dextran‐OSTs that operate at an ultralow energy consumption (15.89 aJ) exhibit multimodal neuromorphic computation ability with excellent synaptic plasticity, including pair‐pulse facilitation (PPF, as high as 494%), spike voltage/frequency/duration/number‐dependent plasticity, and a high recognition accuracy of 89.95% by handwritten digital datasets. Furthermore, the device exhibits visual self‐adaptation ability and audiovisual fusion effect, showcasing the immense potential in self‐adaptation and synergy sensing. More importantly, the dextran‐OSTs can significantly advance the capabilities of binary optical information processing and memorizing. This demonstrates the great advantages of dextran‐OSTs in multimodal neuromorphic computation, visual self‐adaptation, synergy sensing, and multiband optical communication.

Three-dimensional matter wave soliton transformation between different optical lattices in a cold Rydberg atomic system

We present a novel approach to realize three-dimensional (3D) matter wave solitons (MWSs) transformation between different optical potential wells by manipulating their depths and centers. The 3D MWSs are obtained by the square operator method, and transformed to other types (elliptical/ring/necklace) by performing time evolution with the split-step Fourier method. The effectiveness and reliability of our approach is demonstrated by comparing the transformed solitons with those obtained iteratively using the square operator method. Redistribution of MWSs are observed due to the modulation of potentials. In certain complex optical potential wells, we demonstrate the generation of exotic MWSs, such as double gyration modes, through this transformation approach. Overall, the controllable soliton transformation provides an excellent opportunity for all-optical switching, optical information processing, and various other applications.

Transfer of optical orbital angular momentum under nonreciprocity-reciprocity amplification conversion

Magnet-free optical nonreciprocity has significant applications in quantum communication, quantum networks, and optical information processing. In this research, considering a degenerate two-level thermal atomic system with the Doppler effect of thermal atoms, the nonreciprocal amplification (NRA) of dual-path degenerate four-wave mixing (FWM) signals is achieved under the action of a co-propagating pumping field. On this basis, spatially multiplexed multiple FWM processes are formed by introducing another counter-propagating pumping field, thereby the reciprocal amplification (RA) of the dual-channel FWM signals is realized. Furthermore, by using multiple sets of spiral phase plates to load spiral phases on the signal light and the pumping light respectively, higher-order Laguerre-Gaussian vortex beams carrying different optical orbital angular momentum (OAM) are generated and participated in the FWM process, which achieve the transfer of the OAM of the pumping light to the amplified FWM fields. Simultaneously, using the Mach-Zehnder interferometer, the conservation characteristics of the OAM of each FWM signal in the NRA-RA conversion are further analyzed. Furthermore, experimental results have demonstrated that in the multiple FWM process induced by a pair of counter-propagating pump fields, the OAM of the amplified FWM signal in each channel varies with the change of that of the pump field. However, the overall process maintains the OAM conservation. The study provides a feasible solution for expanding channel capacity using OAM based on NRA-RA system, and has potential application prospects in achieving high-capacity optical communication and multi-channel signal processing.

Spin-Orbit-Locking Vectorial Metasurface Holography.

Vectorial metasurface holography, allowing for independent control over the amplitude, phase, and polarization distribution of holographic images enabled by metasurfaces, plays a crucial role in the realm of optical display, optical, and quantum communications. However, previous research on vectorial metasurface holography has typically been restricted to single degree of freedom input and single channel output, thereby demonstrating a very limited modulation capacity. This work presents a novel method to achieve multi-channel vectorial metasurface holography by harnessing spin-orbit-locking vortex beams. In each channel, the optical vectorial field is encoded with a pair of total angular momentums (TAMs) featuring two orthogonal spin angular momentums (SAMs) independently locked with arbitrary orbital angular momentums (OAMs). The methodology relies on a modified Gerchberg-Saxton algorithm, enabling the encoding of various TAM channels within a single phase profile. Consequently, a pure geometry-phase metasurface with a non-interleaved approach can be used to support such multi-channel vectorial holography, achieving high selectivity of both SAM and OAM, and offering precise routing and manipulation of complex light channels. The work presents a paradigm shift in the field of holography, offering promising avenues for high-density optical information processing and future photonic device design.

Multiplane Optimizing Phase Holograms Using Advanced Machine Learning Algorithms and GPU Acceleration

Phase holography is a critical optical imaging and information processing technique with applications ranging from microscopy to optical communications. However, optimizing phase hologram generation remains a significant challenge due to the non-convex nature of the optimization problem. This paper presents a novel multiplane optimization approach for phase hologram generation to minimize the reconstruction error across multiple focal planes. We significantly improve holographic reconstruction quality by integrating advanced machine learning algorithms like RMSprop and Adam with GPU acceleration. The proposed method utilizes TensorFlow to implement custom propagation layers, optimizing the phase hologram to reduce errors at strategically selected distances.

Optical properties of Gd3+ doped bismuth silicate crystals based on first principles

Bismuth silicate (Bi4Si3O12, BSO) crystal, as a nonlinear optical material with excellent optical properties, has a wide range of applications in laser technology, optical communication, and optical information processing. In order to further improve its performance, this study adopts a first principles calculation method based on density functional theory (DFT), selects Gd3+ as the dopant, and calculates and explores the changes in optical properties of BSO crystals after doping with 1/12, 1/6, and 1/3Gd3+. The calculation results show that the doping of Gd3+ changes the electronic structure of BSO crystals, which is manifested in the emergence of new light absorption and emission characteristics, an increase in carrier concentration, an improvement in conductivity, and an enhancement of crystal polarization ability in optical properties. In addition, doping with Gd3+ increases the light transmission rate and reduces energy loss of BSO crystals, while releasing more energy during electron band transitions, effectively improving the luminescence performance of BSO crystals. The theoretical research in this article provides an important theoretical basis for understanding the influence of Gd3+ doping on the optical properties of BSO, and by optimizing the ratio of Gd3+, the optical properties of BSO can be further regulated, opening up new possibilities for its application in optoelectronic devices.

Design and implementation of broadband optical vortices in photonic crystal slabs

We propose and discuss a simple method to generate broadband optical vortices, utilizing the inherent topological vortex structures of polarization around bound states in the continuum supported by a photonic crystal slab in the momentum space to induce the generation of vortex beams. Since the proposed structure is composed of silicon pillars arranged periodically, it lacks a true optical geometric center. It is insensitive to the position of the incident light and does not require a specific optical alignment process compared to traditional spiral phase plates. Furthermore, because it is composed of dielectric pillars, it can achieve vortex beam generation at any desired working wavelength. We also discuss the robustness of its structure, showing that it can be immune to certain manufacturing defects. Therefore, the proposed structure not only provides a new method for manipulating the angular momentum of photons but also has potential new applications in integrated optical information processing and optical tweezers.

Coherent control of dressing interaction of sequential-doubly-dressed four-wave mixing

Abstract We investigate the coherent control of dressing interaction in four-wave mixing (FWM) in a Y-type four-level atomic system based on the dressed states theory. We study the density matrix equation acted by two dressing fields simultaneously governing FWM signal intensity and the eigenvalues under the dressed state formalism. It is shown that the peak position and intensity of Autler–Townes splitting both originate from the dressing interaction as the detuning of the probe field is scanned. Moreover, it is observed that the interaction could be controlled by the dressing fields. Such flexibly controlled nonlinear signal has potential applications in optical communication and quantum information processing.

All‐Optical Imaging Using Perovskite Nanocrystals Based on Spectro‐Spatial Correlation

AbstractThe exponential growth of data from sensors and internet‐connected devices has challenged traditional electronic computing, particularly in processing speed and power efficiency. Optical information processing, with its inherent high speed and parallelism, offers a promising solution. Moreover, optical processing is vital for developing all‐optical networks, where all‐optical imaging is essential. In this paper, a novel all‐optical imaging technique that leverages in situ anion exchange reactions between perovskite nanocrystals to create an array of pixels with tunable emission wavelengths is proposed. This method enables the conversion of UV light, whether transmitted or reflected by an object, into the visible spectrum, thereby establishing a direct correlation between spectral and spatial information. By employing wavelength division multiplexing (WDM), the approach reduces the dimensionality of information acquisition from two dimensions to one, enhancing imaging speed. This innovation paves the way for significant advancements in all‐optical imaging and image processing, offering new possibilities for faster and more efficient imaging technologies.

Piezoelectric actuation for integrated photonics

Recent decades have seen significant advancements in integrated photonics, driven by improvements in nanofabrication technology. This field has been developed from integrated semiconductor lasers and low-loss waveguides to optical modulators, enabling the creation of sophisticated optical systems on a chip-scale capable of performing complex functions such as optical sensing, signal processing, and metrology. The tight confinement of optical modes in photonic waveguides further enhances the optical nonlinearity, leading to a variety of nonlinear optical phenomena such as optical frequency combs, second-harmonic generation, and supercontinuum generation. Active tuning of photonic circuits not only is crucial for offsetting variations caused by fabrication in large-scale integration but also serves as a fundamental component in programmable photonic circuits. Piezoelectric actuation in photonic devices offers a low-power, high-speed solution and is essential in the design of future photonic circuits due to its compatibility with materials such as Si and Si3N4, which do not exhibit electro-optic effects. Here, we provide a detailed review of the latest developments in piezoelectric tuning and modulation by examining various piezoelectric materials, actuator designs tailored to specific applications, and the capabilities and limitations of current technologies. In addition, we explore the extensive applications enabled by piezoelectric actuators, including tunable lasers, frequency combs, quantum transducers, and optical isolators. These innovative ways of managing photon propagation and frequency on-chip are expected to be highly sought after in the future advancements of advanced photonic chips for both classical and quantum optical information processing and computing.

Generation of an Ultra‐Long Transverse Optical Needle Focus Using a Monolayer MoS2 Based Metalens

AbstractLine‐scan mode enables rapid and high‐throughput imaging through the development of an appropriate optical transverse needle focus. Diffraction gratings allow the generation of a line focus, but they face the challenge of low light power utilization due to multiple high‐order diffractions. In addition, designing the focus requires the selection of functional materials. Atomically thin transition metal dichalcogenides with high dielectric constants provide significant phase shifts to incident light by utilizing phase singularity at zero reflection. However, at zero reflection, no light power is available for utilization, necessitating a balance between phase and amplitude modulation. In this work, the aforementioned issues are addressed by designing a monolayer MoS2 based Fresnel strip metalens. An optical needle primary focus with a transverse length of 40 µm (≈80 λ, the longest value reported to date), a sub‐diffraction‐limited lateral spot, and a broad range of working wavelengths are achieved using the metalens. The metalens not only concentrate light power in the primary diffraction order by overcoming the constraint of momentum conservation but also maintains a constant phase modulation between distinct strips. The novel method for optical manipulation present here holds great promise for applications in biology, oncology, nanofabrication, energy harvesting, and optical information processing.

Investigation of metal-insulator-metal waveguides with elliptical-nanodisk resonator for high contrast ratio all-optical logic gates

Abstract This research focuses on the design and analysis of all-optical Exclusive OR(XOR), NOT, and OR logic gates based on metal-insulator-metal waveguides with elliptical-nanodisk resonators. The functionality of the proposed optical logic gates is determined by constructive and deconstructive signals which are applied to the input ports and control ports. To show the logic 0 (low) and logic 1 (high) output states, the limit of threshold transmission is 1.775 × 10−13 ∼0. The transmission (T) and contrast ratio (CR) are obtained to present the performance of the optical logic gates via the method of finite-difference time-domain. The maximum transmission is reached for the OR gate as 1.38 and the highest contrast ratio is 124.75 dB for the XOR and NOT logic gates. The designed logic devices are promising for improving more efficient optical signal information processing devices.

A fixed phase tunable directional coupler based on coupling tuning

The field of photonic integrated circuits has witnessed significant progress in recent years, with a growing demand for devices that offer high-performance reconfigurability. Due to the inability of conventional tunable directional couplers (TDCs) to maintain a fixed phase while tuning the reflectivity, Mach-Zehnder interferometers (MZIs) are employed as the primary building blocks for reflectivity tuning in constructing large-scale circuits. However, MZIs are prone to fabrication errors due to the need for perfect balanced directional couplers to achieve 0-1 reflectivity, which hinders their scalability. In this study, we introduce a design of a TDC based on coupling constant tuning in the thin film Lithium Niobate platform and present an optimized design. Our optimized TDC design enables arbitrary reflectivity tuning while ensuring a consistent phase across a wide range of operating wavelengths. Furthermore, it exhibits fewer bending sections than MZIs and is inherently resilient to fabrication errors in waveguide geometry and coupling length compared to both MZIs and conventional TDCs. Our work contributes to developing high-performance photonic integrated circuits with implications for various fields, including optical communication systems and quantum information processing.

Stabilizing and Guiding Rogue Waves in a Cold Atomic Gas

AbstractRogue waves (RWs) are mysterious nonlinear waves and have attracted much attention in recent years. However, they are usually unstable during propagation. Here, a scheme for stabilizing and guiding optical RWs in a cold atomic gas working under the condition of electromagnetically induced transparency is presented. It is shown that an external potential for probe laser field can be created by using an assisting laser field. If the assisting laser field has the form of Gaussian beam, the instability of the RWs can be largely suppressed. It is also shown that the RWs can be stabilized and guided to propagate along curved trajectories if the assisting laser field has the form of Airy beam. The results reported here contribute to the effort for stabilizing and manipulating RWs, which may have potential applications in optical transmission and information processing.

Broadband and widely tunable second harmonic generation in suspended thin-film LiNbO3 rib waveguides

Our study demonstrates second harmonic generation (SHG) in a high confinement LiNbO3 rib waveguide through type-I birefringence phase matching of fundamental modes. The combination of micro-waveguide dispersion and material birefringence reveals unique SHG characteristics that complement the performance of standard LiNbO3 on insulator (LNOI) components. Dual-pump wavelength phase matching in the near-infrared and mid-infrared regions is shown in a given waveguide. These two wavelengths can be positioned in the 1.1–3.5 μm range or converge near 1.5 μm by adjusting the core waveguide size or through temperature tuning. A 25 °C temperature change enables a broad pump tunability band of 300 nm, ranging from 1350 to 1650 nm, with a conversion efficiency exceeding 40 %/W/cm2 within a single waveguide. A temperature tuning range of up to 900 nm is foreseen by tailoring the waveguide core size. In addition, a broadband response of 150 nm within the telecom window is demonstrated experimentally. The nonlinear waveguide, etched in a thin film membrane, is combined with titanium-indiffused waveguides to form a monolithic LiNbO3 component. This configuration provides low coupling losses of 0.8 dB and single-mode operation. It paves the way for a new generation of versatile and cost-effective frequency conversion components with wide-band spectral responses suitable for optical communications, environmental sensing, and quantum information processing.

Characteristics study of a dual-wavelength polarization filter based on gold-filled square lattice photonic crystal fiber

This study proposes a polarization filter based on gold-filled photonic crystal fiber (PCF) with a square lattice structure. Utilizing the finite element method (FEM), the filtering characteristics of the model were numerically simulated. The dispersion relation and loss characteristics of this structure were analyzed, and the optimal structural parameters were obtained through structural adjustments. Furthermore, the performance of the filter was evaluated under a 2% variation in manufacturing tolerances for gold film thickness (), air hole spacing (), and air hole diameters () and (). Results indicated that at the 1310 nm and 1550 nm communication windows, the confinement losses of the filter were 1354.6 dB/cm and 869.04 dB/cm, respectively, while the losses for the -polarization were merely 16.97 dB/cm and 0.98 dB/cm. When the filter length was set to 0.5 mm, the maximum extinction ratios (ERs) for the two windows reached 588.2 dB and 370.6 dB, and the filter bandwidth extended to 640 nm. Moreover, the characteristics of the filter under manufacturing tolerances were computed, revealing that the filter’s performance remained stable and feasible despite manufacturing errors. The proposed rectangular gold-coated PCF is anticipated to have broad applications in optical fiber communication and optical information processing.

Dissimilar soliton molecule formed by dissipative pulses in a single-mode mode-locked fiber laser.

Soliton molecules, or also known as optical bound states, are the most representative example of solitons' particle nature and have given birth to diverse light-matter analogies. Despite detailed research on regular bound states, the soliton molecule synthesis of dissimilar pulses has rarely been reported. Here, soliton molecules formed by dissimilar dissipative solitons are demonstrated in a single-mode mode-locked fiber laser, with an in-depth analysis of their evolution dynamics. This novel bound state features pulse trapping between two ultrafast vector pulses with distinct pulse properties including energy, duration, and chirp, leading to unique temporal and spectral profiles. This laser provides an optimal platform for studying complex interactions between different types of dissipative solitons. The findings here can provide new degrees of freedom for the generation of optical soliton molecules and can fuel applications in optical information processing, metrology, and spectroscopy.

Superluminal propagation of birefringence modes in surface plasmon polaritons through hybrid metallic nanoparticles and chiral systems

We have theoretically investigated the enhancement of superluminal birefringence modes of surface plasmon polaritons (SPPs) at the interface of a chiral quantum dot (QD) nanostructure and a metallic nanoparticle (MNP) hybrid system. This configuration facilitates the generation of SPP birefringence modes when illuminated by incident light. The resonances of SPPs within the hybrid nanostructure are determined through analytical calculations using Maxwell’s equations under specific boundary conditions. Additionally, we model the dynamics of the chiral quantum dots system using the density matrix approach, considering it as a four-level configuration interacting with weak probe, magnetic, and strong coupling fields. Our findings indicate that electron tunneling strength and the intensity of the control field significantly influence the birefringence modes of superluminal SPPs. Furthermore, the observation of negative group index and advanced time in the birefringence beams of SPPs provides evidence for the enhanced superluminal birefringence modes. This research has substantial implications across diverse areas such as optical information processing, temporal cloaking, quantum communication, and the advancement of computer chip speed.