Optical Information Transmission Research Articles

Study of the Dispersion Compensation Double-Layer Diffractive Optical Components Based on Metasurface and Grating, and Their Application in Augmented Reality Displays.

We employed a double-layer coupled diffractive optical element, based on metasurfaces and diffraction gratings, which exhibits wavefront modulation and chromatic dispersion compensation. Utilizing this double-layer coupled diffractive optical element in the optical information transmission process of a diffractive waveguide allows for the transmission of color image information using a single-layer waveguide structure. Our results demonstrate that, under the conditions of a field of view of 47° × 47°, an entrance pupil size of 2.9 × 2.9 mm2, and an exit pupil extension size of 8.9 mm, the uniformity of the brightness for each monochromatic field reached 85%, while the uniformity of color transmission efficiency exceeded 95%.

Tunable Liquid Crystal Twisted‐Planar Fresnel Lens for Vortex Topology Determination

AbstractThe development of straightforward and effective methods to determine the topological charge of phase singular beams is crucial for broadening the applications of optical vortices. Here, a straightforward and elegant method for determining the topological charge of an optical vortex using an innovative switchable achromatic nematic liquid crystal Fresnel lens is proposed. The approach allows for the unambiguous determination of both the absolute value and the sign of the topological charge of a singular beam across a wide range of the visible spectrum, as demonstrated both experimentally and theoretically. The research outcomes are promising for applications in optical information transmission systems, cryptography, and quantum computing.

Design of waveguide with double layer diffractive optical elements for augmented reality displays

We investigated a diffraction optical waveguide structure with a double layer coupling configuration. This double layer-coupled diffraction optical waveguide structure modulates light information through wavefront modulation for propagation within the optical waveguide and then reproduces the light information through further wavefront modulation, thus achieving optical information transmission. Analysis indicates that the theoretical maximum field of view can reach 90° × 90°. With an actual field of view set to 53° × 53°, an entrance pupil size of 3.2 × 3.2 mm², an eye relief of 10 mm, and 50 pupil expansion, the system’s total energy transmission efficiency is 37%, with field of view uniformity at 91% and uniformity within the eye movement range reaching 97%.

Encryption-decryption scheme in a single-pixel system based on polarization and Laguerre-Gaussian mode modulation

Optical cryptosystems are crucial for ensuring the security of optical information transmission and storage. The indirect measurement mechanism of single-pixel imaging (SPI) offers a feasible implementation channel for optical cryptosystems. Illumination patterns are encryption keys projected onto the plaintext object, while the intensity collected by the single-pixel detector forms the ciphertext. However, the variations in the object's angular position during SPI measurement generally introduce certain inaccuracies in image reconstruction. And due to SPI's input-output linear mapping relationship, the plaintext is vulnerable to exposure. This proposes an encryption-decryption scheme in a single-pixel system based on polarization and Laguerre-Gaussian (LG) mode modulation. The inherent circular symmetry of LG mode makes the angular position of the object information that can be encrypted, while the intrinsic properties of the object can be represented by polarization. Our system characterizes various polarization parameters of samples serving as reliable plaintext with an error of less than 4.2%, including depolarization, diattenuation, and retardance. For encryption demonstration, LG modes are randomly divided into 5 groups, corresponding to an object at different rotational states. This, combined with 16 polarization modulations, constructs pattern-angle-polarization joint keys, enabling high-security encryption as well as high-fidelity decryption of the mask image, optical axis orientation, and retardance of the test sample. Experimental results demonstrate the effectiveness of our scheme in enhancing the security and information complexity of optical cryptography, offering valuable insights for optical communication and quantum information security.

Observation of off-axis solitary waves propagating along a specific trajectory in photorefractive crystals.

We report the propagation dynamics of swallowtail beams (SBs) within a photorefractive crystal. In the nonlinear regime, the self-accelerating and secondary self-focusing features of the swallowtail beams are influenced, and a solitary wave is generated. The main lobe energy of the swallowtail beams is guided to a specific inclined trajectory, leading to a stable solitary wave, and we control the output position of the solitary wave by changing the launch angle. Our results are supported by the corresponding experiments. In addition, we demonstrate that a Gaussian beam can be effectively guided in swallowtail optical waveguide structures. Our research represents an interesting interaction between the swallowtail beams and nonlinear medium, which may find potential applications in photonic integrated devices and optical information transmission.

Liquid microlens compound structure for enhanced sub-micron resolution imaging and accelerated reconfigurable deformation manipulation

The optical observation of sub-micron structures encounters significant challenges due to the inadequate spatial shape matching of optical devices and the limitations imposed by diffraction. These factors result in suboptimal imaging resolution and the introduction of defocus distortion. One approach to mitigating these limitations involves utilizing a liquid microlens (LML) assisted microscope, which offers real-time and localized control capabilities. However, the dynamic tuning of LML is subject to volatility and instability, adversely affecting sub-micron resolution imaging. To address this issue, a contour-following coating inspired by the natural cornea is applied to the droplet's surface, resulting in the formation of liquid microlens compound structures (LMLCS). Firstly, photoresist microholes are fabricated on the optical disc. Then, liquid self-assembly technology is used to fill glycerol in the microholes. At last, a conformal spreading method of UV-curable adhesive precursor film is developed to ensure the combination of the microlens bilayer structure. Through the application of optical information transmission theory, finite difference time domain (FDTD) method, and the principle of Abbe microscopic imaging, the imaging magnification process and sub-micron resolution characteristic of the LMLCS are revealed. Remarkably, the obtained focal width at half maximum (FWHM) of 1.54 μm is smaller than the theoretical value, enabling reconfigurable sub-micron resolution observation and 1.63 times imaging magnification of 226 nm grating lines under the optical microscope. Compared with unencapsulated LML, this compound structure exhibits better sub-micron resolution capability, greater imaging magnification, and faster adaptive dynamic response characteristics. Consequently, the LMLCS introduces exciting prospects for exploring optical sub-micron measurement and sensing devices with exceptional performance.

Pulsed‐Laser Deposition of Ge‐Doped BiTe Nanofilms and Their Application in Room‐Temperature Long‐Wave Infrared Photodetection

AbstractLong‐wave infrared photodetectors play an indispensable role in a variety of fields such as science, technology, engineering, and medicine. However, to date, most conventional long‐wave infrared photodetectors need to be operated under low temperature to meet the performance requirements. This can lead to a series of problems such as large device volume and high operating cost. Therefore, it is urgent to explore novel long‐wave photosensitive materials. In recent years, the development of nanotechnology has opened a new door for long‐wave infrared photodetection. Herein, pulsed‐laser deposition is successfully applied to the preparation of Ge‐doped BiTe (GBT) thin films. Importantly, the corresponding GBT photodetector exhibits excellent long‐wave infrared photosensitivity. Specifically, upon 10.5 µm illumination, the responsivity, external quantum efficiency, and detectivity reach 1.41 mA W−1, 0.017%, and 1.96 × 106 Jones, respectively. Moreover, a fast response rate with the rise/decay time down to 42.5/41.1 µs is realized. On this basis, the GBT photodetector is used as the receiving unit for optical signals to achieve proof‐of‐concept long‐wave optical information transmission application. On the whole, this study provides a new material platform for long‐wave optoelectronic sensing.

Nonlinear absorption conversion of epsilon-near-zero multilayer metamaterial at optical frequencies.

Modern all-optical logic switches demand selective, precise, and rapid transmission of optical information. In this study, we investigate an epsilon-near-zero (ENZ) metamaterial composed of silver (Ag) and magnesium fluoride (MgF2), which demonstrates a low conversion threshold, strong nonlinear response, and nonlinear absorption conversion. Particularly noteworthy is its highest nonlinear absorption (β≈-2 × 106 cm/GW) occurring at the ENZ point (695 nm) under deposited condition. This research marks the first discussion of nonlinear absorption conversion in the ENZ multilayer metamaterial. The deposited metamaterial sample exhibits saturation absorption (SA), attributed to ground state free electron bleaching, while annealed sample shows a transition from SA to reverse saturation absorption (RSA) due to a three-photon absorption effect. Annealing significantly reduces the laser power threshold required for this conversion process, indicating reduced risk of laser-induced damage. Furthermore, the wavelength shift of the largest RSA (γ≈1.93 × 104 cm3/GW2) in the annealed sample aligns with the expected redshift direction of the ENZ region (735 nm). Our metamaterial design achieves enhanced nonlinear absorption and low-power absorption conversion, which holds significant potential for applications in all-optical logic switches.

Ultra-robust informational metasurfaces based on spatial coherence structures engineering

Optical information transmission is vital in modern optics and photonics due to its concurrent and multi-dimensional nature, leading to tremendous applications such as optical microscopy, holography, and optical sensing. Conventional optical information transmission technologies suffer from bulky optical setup and information loss/crosstalk when meeting scatterers or obstacles in the light path. Here, we theoretically propose and experimentally realize the simultaneous manipulation of the coherence lengths and coherence structures of the light beams with the disordered metasurfaces. The ultra-robust optical information transmission and self-reconstruction can be realized by the generated partially coherent beam with modulated coherence structure even 93% of light is recklessly obstructed during light transmission, which brings new light to robust optical information transmission with a single metasurface. Our method provides a generic principle for the generalized coherence manipulation on the photonic platform and displays a variety of functionalities advancing capabilities in optical information transmission such as meta-holography and imaging in disordered and perturbative media.

Creation and manipulation of optical Meron topologies in tightly focused electromagnetic field

The optical topology, which serves as a stable spatial electromagnetic structure, offers a new dimension for applications in the field of optical information processing, transmission, and storage. In recent years, there has been an increasing focus on these spatially structured light fields. By reversing the radiation of orthogonal dipole pairs, we propose an approach to generate Meron topologies within the focused light field while also investigating the evolution of the Meron structure along the longitudinal axis. Through introducing a dipole placed along the z-axis, we achieve precise positioning and fine adjustment of the topological center. The stability of Meron under a high numerical aperture objective lens (NA = 0.95) can be effectively demonstrated.

Optical Information Transmission and Multimode Fluorescence Anticounterfeiting of Ca2-xMgxGe7O16:Mn2.

Multimode emission of Mn2+ for multimode fluorescence anticounterfeiting is achieved by cation site and interstitial occupancy in Ca2-xMgxGe7O16. The rings in Ca2-xMgxGe7O16 have a significant distortion for Mn2+ ions to enter the ring interstitials with a luminescence center at 665 nm, which is supported by XRD refinement results and first-principles calculations. The interstitial Mn2+ ion has good thermal stability with an activation energy of 0.36 eV. Surprisingly, these two luminescence centers, the cation site Mn and the interstitial Mn, have an obvious afterglow, and the disappearing afterglow will reappear by heating or irradiating with the 980 nm laser. The afterglow is significantly enhanced, as MnO2 is used as the manganese source, which is explained in detail by the thermal luminescence spectrum. Finally, Ca2-xMgxGe7O16:Mn2+ fully demonstrates its excellent prospects in fluorescent anticounterfeiting, information encryption, and optical information storage.

High-fidelity multi-channel optical information transmission through scattering media.

High-fidelity optical information transmission through strongly scattering media is challenging, but is crucial for the applications such as the free-space optical communication in a haze or fog. Binarizing optical information can somehow suppress the disruptions caused by light scattering. However, this method gives a compromised communication throughput. Here, we propose high-fidelity multiplexing anti-scattering transmission (MAST). MAST encodes multiple bits into a complex-valued pattern, loads the complex-valued pattern to an optical field through modulation, and finally employs a scattering matrix-assisted retrieval technique to reconstruct the original information from the speckle patterns. In our demonstration, we multiplexed three channels and MAST achieved a high-fidelity transmission of 3072 (= 1024× 3) bits data per transmission and average transmission error as small as 0.06%.

Physical conversion and superposition of optical skyrmion topologies

Optical skyrmions are quasiparticles with nontrivial topological textures that have significant potential in optical information processing, transmission, and storage. Here, we theoretically and experimentally achieve the conversion of optical skyrmions among Néel, Bloch, intermediate skyrmions, and bimerons by polarization devices, where the fusion and annihilation of optical skyrmions are demonstrated accordingly. By analyzing the polarization pattern in Poincaré beams, we reveal the skyrmion topology dependence on the device, which provides a pathway for the study of skyrmion interactions. A vectorial optical field generator is implemented to realize the conversion and superposition experimentally, and the results are in good agreement with the theoretical predictions. These results enhance our comprehension of optical topological quasiparticles, which could have a significant impact on the transfer, storage, and communication of optical information.

Giant nonlocal Kerr nonlinearity and polaritonic solitons in a Rydberg-dressed Bose-Einstein condensate.

We present a scheme to generate nonlocal optical Kerr nonlinearity and polaritonic solitons via matter-wave superradiance in a Rydberg-dressed Bose-Einstein condensate (BEC). We show that the polariton spectrum of the scattered field generated by the superradiance is changed significantly due to the existence of the long-range Rydberg-Rydberg interaction between atoms, i.e. it has a roton-maxon form; moreover, the BEC structure factor displays a strong dependence on the Rydberg-dressing, which can be tuned in a controllable way. We also show that such a Rydberg-dressed BEC system can support a giant nonlocal optical Kerr nonlinearity, and hence allow the formation and stable propagation of polaritonic solitons, which have ultraslow propagation velocity and ultralow generation power. The results reported here are useful to understand the unique properties of Rydberg-dressing in BECs and have potential applications in optical information processing and transmission.

Two-Dimensional Quasi-Periodic Diffraction Properties of the Scalar and Vector Optical Fields

As is known, quasi-periodicity attracts great attention in many scientific regions. For instance, the discovery of the quasicrystal was rewarded the Nobel Prize in 2011, leading to a series of its applications. However, in the area of manipulating optical fields, the two-dimensional quasi-periodicity is rarely considered. Here, we study the two-dimensional quasi-periodic diffraction properties of the scalar and vector optical fields based on the Penrose tiling, which is one of the most representative kinds of two-dimensional quasi-periodic patterns. We propose type-A and type-B Penrose tiling masks (PTMs) with phase modulation, and further show the diffraction properties of the optical fields passing through these masks. The intensity of the diffraction field holds a tenfold symmetry. It is proved that the iteration number n of the PTM shows the “weeding” function in the diffraction field, and this property is useful in filtering, shaping, and manipulating diffraction fields. Meanwhile, we also find that the diffraction patterns have the label of the Golden ratio, which can be applied in areas such as optical encryption and information transmission.

Light wave propagation and diffraction inhibition in three-dimensional photonic quasicrystal lattices

We have investigated the linear propagation of light wave in three-dimensional photonic quasicrystal lattices by numerical simulation. The diffraction characteristics of the light waves in the longitudinal non-modulated, in-phase modulated and out-of-phase modulated quasicrystal lattices have been compared and discussed. We have demonstrated the diffraction inhibition of light wave in three-dimensional photonic quasicrystals. Linear transverse light localization has been realized in the longitudinal out-of-phase modulated three-dimensional quasicrystal lattices by adjusting the structural parameters appropriately. Furthermore, the results also show that the longitudinal out-of-phase modulated photonic quasicrystals are easier to produce diffraction inhibition than the longitudinal out-of-phase modulated periodic lattices under low transverse refractive index contrast. Distortionless dot image transmission has numerically demonstrated in out-of-phase modulated photonic quasicrystals array. It provides a new way for distortion-free image transmission, which has promising applications in optical information transmission and all-optical signal processing.

Modulate scattered light field with Point Guard Algorithm

Speed and quality of wavefront shaping (WFS) are considered to be two major challenges in anti-scattering optical information transmission. Confronted with this, a novel optimization approach, namely Point Guard algorithm (PGA), is proposed based on the movement strategies of Point Guard (PG) in professional basketball association. The PGA manipulates the optical interference by encoding the digital micromirror device (DMD). The performance of the PGA can only be affected by one parameter (boundary value, BV), and the strategy of self-adaptive updating is adopted for this parameter to accelerate the speed of searching optimal pattern. Compared with the most popular WFS method genetic algorithm (GA), the PGA improves the speed and peak-to-background ratio (PBR) of single-point focusing by a factor of 10.49 and 4.05 within 500 iterations. We also accomplish 7-point focusing and form a bright and uniform Z-shape pattern in a short optimization period. Furthermore, it is demonstrated that the PGA can quickly reconstruct the visible image information through the scattering medium. With the ability to uniquely identify its target area, the reconstructed image ensures the secure optical communication. We also experimentally demonstrate that the PGA can parallel reconstruct three images in a short optimization period without obvious cross-talk. This new method has good potential in applications such as optogenetics, optical trapping and optical information transmission in complex environment.

Multicolored Displays with Selective Visible‐Infrared Spectral Modulation for Optical Information Transmission

AbstractPolyaniline (PANI) can achieve reversible optical modulation in visible and infrared (IR) bands under the action of voltage. However, PANI‐based electrochromic devices cannot cope with the dual detection of visible and IR light to realize the transmission of information due to the linkage restriction between the spectral modulation in the visible and IR region. Here, IR low‐absorptive inorganic pigments as colorants and IR high‐transparent polymer as a binder are utilized to prepare colored films with high transparency. A camouflage layer against visible light detection is constructed on the surface of IR electrochromic devices, and the information transmission is realized in the IR band by controlling the thermal radiation characteristics. Furthermore, thermochromic microcapsules (TMs) that change color under external thermal stimuli are introduced to fabricate a thermochromic and IR transparent functional layer, which is attached to the surface of IR electrochromic devices and endows the devices with separate spectral modulation ability in the visible and IR region. Multicolored displays are fabricated by arraying various devices. Moreover, visual patterns are prepared on the surface of IR electrochromic devices by dispensing technology. This configuration endows the device with a promising potential for anti‐counterfeiting, optical security, and related applications.

Anti-scattering optical information transmission based on iterative wavefront shaping in perturbation environment

Improving the quality of wavefront shaping (WFS) is a major problem of anti-scattering optical information transmission in the perturbation environment. To tackle this issue, we propose a simple and robust method, named Point Guard algorithm (PGA), to manipulate the optical interference by encoding the digital micromirror device (DMD). The PGA method is inspired by the movement strategies of Point Guard (PG) in professional basketball association. Compared with the most popular method genetic algorithm (GA), the proposed PGA method has a stronger anti-perturbation capacity. In the experiment, the scattering medium consists of ground glass and polystyrene microspheres (PS) suspended in deionized water, and the movement of microspheres is used to cause a perturbation. It is found that PGA still has a better modulation quality when the suspension is too thick to see the ballistic light. PGA puts a new perspective in applications such as optogenetics and biomedical imaging in complex environment.

Design Strategies and Applications of Dimensional Optical Field Manipulation Based on Metasurfaces.

Recent rapid progress in metasurfaces is underpinned by the physics of local and nonlocal resonances and the modes coupling among them, leading to tremendous applications such as optical switching, information transmission, and sensing. In this review paper, we provide an overview of the recent advances in a broad range of dimensional optical field manipulation based on metasurfaces categorized into different classes based on design strategies. We start from the near-field optical resonances of artificial nanostructures and discuss the far-field optical wave manipulation based on fundamental mechanisms such as mode generation and mode coupling. We summarize the recent advances in optical field manipulation based on metasurfaces in different optical dimensions such as phase and polarization and discuss newly-developed dimensions, such as the orbital angular momentum and the coherence dimensions resulting from phase modulation. Then, we review the recent achievements of multiplexing and multifunctional metasurfaces empowered by multidimensional optical field manipulation for optical information transmission and integrated applications. Finally, we conclude with a few perspectives on emerging trends, possible directions, and existing challenges in this fast-developing field. This article is protected by copyright. All rights reserved.