Holographic Multiplexing Research Articles

Orthogonality of polarization superposition based on polarization holography.

We propose a polarization superposition orthogonal theory based on tensor polarization holography. Based on this theory, the holographic multiplexing capability can be improved measurably. The orthogonality of polarization waves is characterized by the null reconstruction in polarization holography, achieved through the superposition of multiple basic polarization reference waves. This paper analyzes the orthogonality of linear polarization wave superposition and circular polarization wave superposition using the tensor polarization holography theory. Using the polarized holography multiplexing technique, we experimentally verify the orthogonality of polarization wave superposition. Our experimental results align with the theoretical analysis, indicating potential applications in polarization encoding and decoding by this theory, thereby diversifying optical encryption technology Additionally, we demonstrate that polarization superposition orthogonality holds significant promise for optical control technology.

Holographic encryption with power-exponent helicon-conical optical vortices

We present a holographic encryption technique that combines the orbital angular momentum (OAM) multiplexing method with power-exponent helico-conical (PEHC) optical vortices. By incorporating the power exponent and normalization factor of the PEHC beam's phase into the selective modulation of OAM modes, we unlock their potential as encoding degrees of freedom in holographic multiplexing. Through the integration of these parameters with the topological charge, we develop an approach to OAM multiplexing for encryption, increasing both the storage capacity of holographic information and data security. To validate our proposed method, we conducted numerical simulations and optical experiments, which confirmed the promising potential of utilizing the adopted noncanonical vortices as an efficient and reliable strategy for achieving holographic encryption.

Enhanced Performance of Visible Light Communication Using Three-Dimensional Spatial Multi-User Holographic Multiplexing

Enhanced Performance of Visible Light Communication Using Three-Dimensional Spatial Multi-User Holographic Multiplexing

Three-dimensional spatial orbital angular momentum holography

The degree of freedom of orbital angular momentum of light has been used as a new information carrier in optical holographic information processing technology. However, current research on orbital angular momentum holography mainly focuses on two-dimensional orbital angular momentum holography, where the reconstructed two-dimensional holographic image is located in a certain plane in three-dimensional space. How to further implement three-dimensional spatial orbital angular momentum holographic technology and use it to increase the information capacity of holographic communication is still a blank. Here, we implement three-dimensional spatial orbital angular momentum holographic technology based on the degrees of freedom of orbital angular momentum and the positional degrees of freedom of reconstructed two-dimensional images in three-dimensional space. In other words, in the three-dimensional spatial orbital angular momentum holography, the acquisition of the target object image requires not only the correct orbital angular momentum state used for decoding, but also the correct spatial position where the object’s image is detected. In addition, we further investigate the three-dimensional spatial orbit angular momentum holographic multiplexing technology and point out that this multiplexing technology can be used for information encryption. Compared with traditional two-dimensional orbital angular momentum holography, three-dimensional spatial orbital angular momentum holography uses an additional degree of freedom. Therefore, the encryption scheme based on three-dimensional spatial orbital angular momentum holographic technology can further improve the security level of information. Our simulation results and experimental results have verified the feasibility of three-dimensional spatial orbit angular momentum holographic technology and three-dimensional spatial orbit angular momentum holographic encryption technology.

High-capacity and multi-dimensional orbital angular momentum multiplexing holography.

Optical holography has been investigated for enhancing information capacity and encryption. Here, the multi-vortex geometric orbital angular momentum (MVG-OAM) multiplexing holography is proposed and experimentally implemented, which encodes information into MVG beams with different central OAM, sub-beam OAM, and coherent-state phase. The orthogonality of the above three parameters are analyzed, respectively, which point out the feasibility of using them for holographic multiplexing. A three-dimensional multiplexing holography is realized by combining these three parameters, which offers potential applications for information storage, optical encryption, and display.

Spatially multiple-dimensional orbital angular momentum multiplexed holography for information encryption

Optical orbital angular momentum (OAM) holography provides a critical method for holographic information storage systems and experimentally demonstrates the feasibility of holographic multiplexation. Herein, the elliptic perfect optical vortex orbital angular momentum (EPOV-OAM) multiplexed holography is proposed and experimentally implemented. The mode selectivity of the ellipticity and rotation angle are investigated, respectively, which demonstrates that those parameters can be used as additional encoded degrees of freedom for the holographic multiplexing. The combination of the topological charge (TC), scaling factor, rotation angle, ellipticity can provide a four-dimensional multiplexed holography for information encryption. Furthermore, the minimum interval of TC for holographic multiplexing could reach 0.01. The method proposed here can enhance the information capacity and the security level of the holographic optical encryption systems.

Orbital angular momentum holographic multicasting for switchable and secure wireless optical communication links.

The physical dimension of orbital angular momentum (OAM) states of light has been successfully implemented as information carrier in wireless optical communication (WOC) links. However, the current OAM data coding strategies in WOC are mainly limited to the temporal domain, rarely involving the degree of freedom of spatial domain to transmit an image directly. Here, we apply OAM holographic multiplexing technology for spatial information encoding in WOC links. Further, we demonstrate the new concept of OAM holographic multicasting, wherein a beam-steering grating has been utilized for information decoding. To distribute the OAM multiplexing information appropriately in the receiving terminal, the beam-steering grating with controllable topological charges and amplitude weighting coefficients of each diffraction order in the spatial frequency domain has been designed. An iterative algorithm has been introduced to obtain the intensity uniformity >98% at target diffraction orders. As such, this scheme experimentally allows four separate users to receive independent images, which can be switched by modulating the topological charges of the beam-steering gratings at each diffraction order. In addition, this leads to a beam-steering grating-encrypted WOC links, wherein the information can only be decoded by the grating phase with 7 pre-set spatial frequency components. Our results mark a new parallel decoding paradigm of OAM multiplexing holography, which opens up the door for future high-capacity and high-security all-optical holographic communications.

Multiparameter encrypted orbital angular momentum multiplexed holography based on multiramp helicoconical beams

Optical orbital angular momentum (OAM) multiplexed holography has been implemented as an effective method for information encryption and storage. Multiramp helicoconical-OAM multiplexed holography is proposed and experimentally implemented. The mode selectivity of the multiramp mixed screw-edge dislocations, constant parameter K, and normalized factor are investigated, respectively, which demonstrates that those parameters can be used as additional coding degrees of freedom for holographic multiplexing. The combination of the topological charge and the other three parameters can provide a four-dimensional multiplexed holography and can enhance information capacity.

Recent Advances and Prospects of Optical Metasurfaces

As an artificial planar composite medium, optical metasurfaces exhibit powerful multidimensional optical modulations at the subwavelength scale. With the aid of intelligent algorithms, versatile wavefront engineering and holographic multiplexing based on optical metasurfaces are being intensively developed. Micronano manufacturing technology provides indispensable support for proof-of-concept and mass production. With the support of these advanced technologies, optical metasurfaces have been developed for a wide range of applications and their compactness, versatility, and compatibility have been fully demonstrated. In this Perspective, we summarize recent advances. In addition, we discuss the challenges and prospects of optical metasurfaces.

High Bandwidth‐Utilization Digital Holographic Multiplexing: An Approach Using Kramers–Kronig Relations

Holographic Multiplexing In article number 2100273, Zhengzhong Huang and Liangcai Cao introduce Kramers–Kronig relation into the off-axis holographic multiplexing technology to realize the maximum spatial bandwidth utilization of single multiplexed hologram. This helps to improve the iterative-free and constraint-free performance of a quantitative optical system, enlarging and empowering applications in high-throughput, large-scale studies of computational microscopy and biological tissue analysis.

Single-Shot High-Throughput Phase Imaging with Multibeam Array Interferometric Microscopy

High-throughput microscopic imaging is highly desirable in biomedical applications. Advances in computational microscopy have achieved high space-bandwidth products and even permitted gigapixel imaging in a stepwise fashion, yet temporal resolution remains challenging for investigating live-sample dynamics. Here, we report multibeam array interferometric microscopy (MAIM) for a single-shot high space-bandwidth product. The MAIM method overcomes the limitations of conventional digital holographic microscopy, providing complex field reconstruction with a maximum 5-fold field of view (FOV) increase in a single camera acquisition, while maintaining sub-nanometer optical path-length stability. This is achieved by integrating common-path holographic microscopy, multibeam interference technology, and holographic multiplexing technology. The temporal resolving power of MAIM is significantly higher than that of computational illumination microscopy. MAIM has major advantages over previous holographic multiplexing techniques in that it integrates more wavefronts and offers high temporal stability. The fundamentals of MAIM are analyzed theoretically. As a demonstration, we build MAIM prototypes to increase the FOV by factors of 5, 4, and 3, respectively. We present proof-of-concept MAIM imaging results of both natural and artificial samples and show biomedical applications such as monitoring sub-cellular dynamical phenomena in flowing live erythrocytes in vitro and label-free microrefractometry imaging of unstained cancer tissue slices. MAIM gives rise to (ultra)fast or long-term (time-lapse) imaging of nanoscale dynamics of unstained live samples in vitro with a high throughput.

Thermally Reconfigurable Hologram Fabricated by Spatially Modulated Femtosecond Pulses on a Heat-Shrinkable Shape Memory Polymer for Holographic Multiplexing.

Optical security involving the use of light to achieve distinctive vision effects has become a widely used approach for anticounterfeiting. Holographic multiplexing has attracted considerable interest in multiplexing security due to its high degree of freedom for manipulating the optical parameters of incident laser beams. However, the complex and time-consuming fabrication process of metasurface-based holograms and the sophisticated nature of holographic imaging systems have hindered the practical application of holographic multiplexing in anticounterfeiting. Combining holography with shape memory polymers to construct reconfigurable holograms provides a simple and efficient way for holographic multiplexing. This paper proposes a reconfigurable four-level amplitude hologram fabricated on a heat-shrinkable shape memory polymer using spatially modulated femtosecond laser pulses. Simply by triggering the shape recovery of the polymer through heating, the amplitude modulation of light by the hologram is reconfigured through the shrinking of processed microcrater pixels with three diameters, which enables variation to be achieved in reconstructed holographic images. Examples of holographic multiplexing and data encryption are used to validate the proposed method. The proposed economic and simple approach for holographic multiplexing provides an integrated and single-material solution to packaging and optical security, which has extensive potential in anticounterfeiting and optical encryption.

Dual-encryption freedom via a monolayer-nanotextured Janus metasurface in the broadband visible.

As an emerging category of two-faced 2D architecture, the Janus metasurface aims to explore another universal optical property, that is, the wavevector direction (k-direction), and to enable the asymmetric transmission between the opposite directional incidences. It exhibits significant potential in creating versatile multiplexing metasurfaces and an optical isolator in optical communication applications. However, most previous asymmetric functionality shows merely one-way functionality with the other-way simply muted or demands multilayered nanostructure fabrication and alignment. Hence, it remains a great challenge to make a monolayer-nanotextured Janus metasurface with dual-encryption freedom and conquering the difficulty for multilayer alignment and practical operation bandwidth. In this work, we have proposed and experimentally demonstrated a new strategy of a dual-encryption Janus metasurface design with a simple monolayer-nanotextured metasurface coupled with a commercialized film of the half-wave plate. Utilizing the hybridization from two independent geometrical dimensions of rectangular-antennas, our approach ingeniously transforms the polarization-multiplexing into the dual-directional channels. A series of calculations and experimental results demonstrate that our asymmetric approach simultaneously constructs completely independent imaging encryptions for both forward and backward directions. Additionally, our proposed approach becomes a practical scheme with broadband visible-frequency operation and great simplicity in design and nanofabrication. We believe the universal scheme could facilitate to increase the information encoding capacity and holographic multiplexing channels by expanding the illumination wavevector to the full-space (+/-), and it paves the route toward the potential applications in on-chip integration, telecommunications, encryption, information processing, and communication.

Stepwise Dual‐Fabry–Pérot Nanocavity for Grayscale Imaging Encryption/Concealment with Holographic Multiplexing

AbstractMetal–insulator–metal (MIM) nanocavity, as a lossy Fabry–Pérot (FP) scheme, has been widely studied for color filter and perfect absorber functionality, which can be integrated into functional photonic devices. However, such triple‐layered MIM still lacks the ability to induce multiple intensity levels for meticulous grayscale imaging because of strong spectral sensitivity to cavity thickness variation. Moreover, the MIM stack remains unexplored to multiplex a near‐field nanoprinting and holographic imaging because it is challenging to break the mutual dependence relation between the intensity and phase shift. Herein, a new film stack of dual‐Fabry–Pérot (DFP) nanocavity is proposed to create triple‐fold freedom in light modulations: intensity, phase shift and operation wavelength, which can be respectively modulated by the top/bottom/total cavity length. By spatially arranging the stepwise nanocavities, the designed DFP pattern can show multiplexing dual‐channel imaging, which encrypts/conceals a grayscale nanoprinting image and simultaneously projects a far‐field holographic image. Such DFP strategy allows for new possibility of independent light modulation and creates new dimensional degree of freedom for thin‐film nanocavity. The proposed functional DFP strategy enriches the subwavelength building block design for metasurfaces and thin‐film stacks, which would promisingly empower advanced applications in information multiplexing, imaging encryption/concealing, and many other related fields.

Electrically tunable diffuser for holographic multiplexing storage

A polymer-dispersed liquid crystal (PDLC) device is fabricated to serve as a diffuser for random phase encoding of reference beams in holographic storage system. By tuning the applied voltage on the PDLC device, three individual random phase reference waves which are orthogonal to each other can be generated. Therefore, holographic multiplexing scheme can be performed using voltage modulation on the PDLC diffuser. In addition, shift multiplexing technique still can be performed in the storage system. When compared with conventional shift multiplexing, using electrically tunable PDLC diffuser offers additional multiplexing mechanism in the presented technique. Using the proposed PDLC diffuser, the multiplexing numbers can be enhanced three times owing to voltage modulation. A holographic storage system implemented using shift multiplexing and voltage modulation on PDLC diffuser is demonstrated.

Incoherent color digital holography with computational coherent superposition for fluorescence imaging [Invited

We present color fluorescence imaging using an incoherent digital holographic technique in which holographic multiplexing of multiple wavelengths is exploited. Self-interference incoherent digital holography with a single-path in-line configuration and the computational coherent superposition scheme are adopted to obtain color holographic three-dimensional information of self-luminous objects with a monochrome image sensor and no mechanical scanning. We perform not only simultaneous color three-dimensional sensing of multiple self-luminous objects but also color fluorescence imaging of stained biological samples. Color fluorescence imaging with an improved point spread function is also demonstrated experimentally by adopting a Fresnel incoherent correlation holography system.

Off-axis digital holographic multiplexing for rapid wavefront acquisition and processing

Off-axis holographic multiplexing involves capturing several complex wavefronts, each encoded into off-axis holograms with different interference fringe orientations, simultaneously, with a single camera acquisition. Thus, the multiplexed off-axis hologram can capture several wavefronts at once, where each one encodes different information from the sample, using the same number of pixels typically required for acquiring a single conventional off-axis hologram encoding only one sample wavefront. This gives rise to many possible applications, with focus on acquisition of dynamic samples, with hundreds of scientific papers already published in the last decade. These include field-of-view multiplexing, depth-of-field multiplexing, angular perspective multiplexing for tomographic phase microscopy for 3-D refractive index imaging, multiple wavelength multiplexing for multiwavelength phase unwrapping or for spectroscopy, performing super-resolution holographic imaging with synthetic aperture with simultaneous acquisition, holographic imaging of ultrafast events by encoding different temporal events into the parallel channels using laser pulses, measuring the Jones matrix and the birefringence of the sample from a single multiplexed hologram, and measuring several fluorescent microscopy channels and quantitative phase profiles together, among others. Each of the multiplexing techniques opens new perspectives for applying holography to efficiently measure challenging biological and metrological samples. Furthermore, even if the multiplexing is done digitally, off-axis holographic multiplexing is useful for rapid processing of the wavefront, for holographic compression, and for visualization purposes. Although each of these applications typically requires a different optical system or processing, they all share the same theoretical background. We therefore review the theory, various optical systems, applications, and perspectives of the field of off-axis holographic multiplexing, with the goal of stimulating its further development.

Multiwavelength three-dimensional microscopy with spatially incoherent light, based on computational coherent superposition.

In this Letter, we propose spatially incoherent multiwavelength three-dimensional (3D) microscopy that exploits holographic multiplexing and is based on computational coherent superposition (CCS). The proposed microscopy generates spatially incoherent wavelength-multiplexed self-interference holograms with a multiband-pass filter and spatially and temporally incoherent light diffracted from specimens. Selective extractions of 3D spatial information at multiple wavelengths from the holograms are realized using the CCS scheme. We constructed fully mechanical-motion-free holographic multiwavelength 3D microscopy systems and conducted experiments to demonstrate the microscopy.

Four‐Wave Mixing Holographic Multiplexing Based on Nonlinear Metasurfaces

AbstractMetasurfaces are utilized to realize computer‐generated holograms (CGHs), with excellent wavefront shaping ability and ultrasmall footprint. To increase the information capacity of metasurface holograms, smart multiplexing techniques together with suitable designs are highly demanded. However, so far only a few approaches to achieve nonlinear metasurfaces holographic multiplexing based on CGHs are proposed, due to limited freedoms of multiplexing and proper metasurfaces' design. The nonlinear interaction of light with the metasurface can generate new frequencies compared to the input laser beam, which is promising to realize spectral and spatial multifunctional wavefront manipulation. Here, a four‐wave mixing (FWM) holographic multiplexing technique is numerically proposed using a nonlinear metasurface composed of a nanoapertures array. It is demonstrated that the complex amplitude modulation by such a metasurface through the FWM process can be utilized for amplitude‐only CGHs, which can process significantly independent information at different nonlinear frequencies in the optical regime. Utilizing the spatial and spectral multiplexing of nonlinear metasurfaces holography, they can be found applications for multidimensional holographic displays and can provide enhanced security for optical data storage. These results show that nonlinear metasurfaces are promising for applications of arbitrary frequency conversion and optical encryption and anticounterfeiting designs.

Silicon Metasurfaces for Third Harmonic Geometric Phase Manipulation and Multiplexed Holography.

Nonlinear wavefront control is a crucial requirement in realizing nonlinear optical applications with metasurfaces. Numerous aspects of nonlinear frequency conversion and wavefront control have been demonstrated for plasmonic metasurfaces. However, several disadvantages limit their applicability in nonlinear nanophotonics, including high dissipative loss and low optical damage threshold. In contrast, it has been shown that metasurfaces made of high-index dielectrics can provide strong nonlinear responses. Regardless of the recent progress in nonlinear optical processes using all-dielectric nanostructures and metasurfaces, much less advancement has been made in realizing a full wavefront control directly with the generation process. Here, we demonstrate the nonlinear wavefront control for the third-harmonic generation with a silicon metasurface. We use a Pancharatnam-Berry phase approach to encode phase gradients and holographic images on nanostructured silicon metasurfaces. We experimentally demonstrate the polarization-dependent wavefront control and the reconstruction of an encoded hologram at the third-harmonic wavelength with high fidelity. Further, we show that holographic multiplexing is possible by utilizing the polarization states of the third harmonic generation. Our approach eases design and fabrication processes and paves the way to an easy to use toolbox for nonlinear optical wavefront control with all-dielectric metasurfaces.