Analysis of transmission jitter in amplitude-type optically addressed spatial light modulators

Achieving spatiotemporal control of light at subwavelength and subcycle scales is an important milestone in the development of new photonic materials for signal processing, pulse shaping and ultrafast imaging. Spatiotemporal light modulation currently relies on electronic interband and intraband transitions that yield pronounced refractive index changes but typically suffer from slow, picosecond response times due to carrier relaxation. Here we show that by leveraging resonant light-matter interactions in a high-quality factor metasurface it is possible to use the optical Kerr effect, a weaker but subfemtosecond optoelectronic polarization effect, to achieve ultrafast, reconfigurable light modulation. By the subwavelength all-optical tuning of the refractive index of the dielectric metasurface unit cells with a spatially structured pump beam, we experimentally demonstrate pulse-limited beam steering with a 74-fs response time at angles up to ±13° in the near-infrared, where the deflection angles are programmable by the pump pattern. The steering originates from the Kerr effect, with a background contribution arising from a slower two-photon-excited free carrier absorption. Additionally, we observe pump self-modulation and self-diffraction, linear frequency conversion, and demonstrate arbitrary subpicosecond spatial light modulation in two dimensions.

Two-dimensional transition metal dichalcogenides are promising candidates for nonlinear photonics applications, offering strong nonlinear susceptibility and compatibility with integrated platforms. Although considerable effort has been devoted to manipulating second harmonic generation in these materials, the dynamic control of nonlinear wavefronts remains largely unexplored. Metasurfaces have enabled significant progress in nonlinear beam engineering, yet their practical implementation is limited by low conversion efficiencies and restricted design flexibility. In this work, we employ feedback-based wavefront shaping using spatial light modulators to enhance SHG from pyramid-like WS2 multilayer structures by over three orders of magnitude in selected spatial regions. This approach allows us to program nonlinear holograms and dynamically shape the SHG signal through phase-only modulation, opening new possibilities for nonlinear imaging, optical information processing, and data communication.

3D image display is essential for next-generation volumetric imaging; however, dense depth multiplexing for 3D image projection remains challenging because diffraction-induced cross-talk rapidly increases as the axial image planes get closer. Here, we introduce a 3D display system comprising a digital encoder and a diffractive decoder, which simultaneously projects different images onto multiple target axial planes with high axial resolution. By leveraging multi-layer diffractive wavefront decoding and deep learning-based end-to-end optimization, the system achieves high-fidelity depth-resolved 3D image projection in a snapshot, enabling axial plane separations on the order of a wavelength. The digital encoder leverages a Fourier encoder network to capture multi-scale spatial and frequency-domain features from input images, integrates axial position encoding, and generates a unified phase representation that simultaneously encodes all images to be axially projected in a single snapshot through a jointly-optimized diffractive decoder. We characterized the impact of diffractive decoder depth, output diffraction efficiency, spatial light modulator resolution, and axial encoding density, revealing trade-offs that govern axial separation and 3D image projection quality. We further demonstrated the capability to display volumetric images containing 28 axial slices, as well as the ability to dynamically reconfigure the axial locations of the image planes, performed on demand. Finally, we experimentally validated a two-plane optical prototype using a single-layer physical decoder, demonstrating close agreement between the measured results and the target images. These results establish the diffractive 3D display system as a compact and scalable framework for depth-resolved snapshot 3D image projection, with potential applications in holographic displays, AR/VR interfaces, and volumetric optical computing.

Perfect optical vortices (POVs) are annular beams designed such that their radii are, in principle, independent of topological charge, making them attractive for structured illumination and optical manipulation. We present a systematic experimental and numerical study of POVs generated using a phase-only spatial light modulator and investigate how controlled angular anisotropy reshapes their structure across a wide range of charges. Three distinct regimes are identified. In the absence of anisotropy, charge-invariant annuli persist only for moderate charges, while higher charges exhibit multi-ring, Bessel-like structure accompanied by a gradual increase in effective radius. At moderate anisotropy, these multi-ring profiles consolidate into single opened annuli with tunable azimuthal asymmetry. In this regime, speckle cross-correlation remains structured even for widely separated charges that exhibit weak correlations under isotropic encoding. At extreme anisotropy, annular intensity profiles converge across all charges, forming pseudo-POVs that remain annular in intensity but exhibit pronounced redistribution of OAM-dependent signatures and a collapse of charge-dependent cross-correlation signatures within the sensitivity of intensity-only measurements. Non-interferometric speckle analysis supports these findings. Autocorrelation rules out trivial ellipticity as the origin of radius convergence, while cross-correlation reveals sensitivity to charge ordering at low anisotropy and an effective loss of charge distinguishability within intensity-only diagnostics at extreme anisotropy. Together, these results clarify the robustness limits of POVs under angular deformation and establish angular anisotropy as a practical control parameter for engineering and diagnosing annular vortex beams.

This research proposed a novel multiple-image encryption scheme using ultrafast light springs. The encryption process begins with the random phase encoding of input images, followed by multiplication with distinct orbital angular momentum (OAM) modes. The modulated signals are then processed using a 4-f ultrashort pulse shaper. The dynamic optical amplitude and phase control of the signal was achieved via a liquid crystal-based spatial light modulator (SLM). The resulting light springs, characterized by helical phase and intensity profiles, are generated through the superposition of multiple laser frequency components. The integration of a double random phase encoding (DRPE) with tailored pulse-shaping operations has further converted the encrypted images to ultrashort pulse springs. This approach extends the temporal characteristics of OAM multiplexing encryption, significantly enhancing the system's encryption capability, key space, and security. The performance of the proposed system is evaluated using multiple security metrics including key sensitive analysis, entropy analysis, correlation analysis, and resistance to attacks. The systematic evaluation demonstrated robustness of this encryption technique and highlighted its potential applications for optical image encryption and real-time secure communication.

With the expanding clinical applications of optical coherence tomography, the inherent tradeoff between high transverse resolution and insufficient depth of focus has become increasingly pronounced. Improved lateral resolution drastically reduces the usable focal depth, compromising consistent image quality across the axial imaging range. To address this core limitation, we propose a liquid crystal metalens incorporating geometric phase corrected by an inverse-quartic axicon phase. Then, the proposed metalens was fabricated by a polarization-exposure system based on a spatial light modulator, where the calculated phase was transformed into the polarization-sensitive geometric phase. The experimental results demonstrate that the developed metalens achieves a 0.5 mm focal depth with left-handed circularly polarized illumination at an incident wavelength of 1550 nm. Within this axial range, the measured focal spots maintain a full-width at half-maximum of around 9 µm. Therefore, the proposed metalens has both high lateral resolution and a large depth of focus, providing a practical solution for optical coherence tomography systems and demonstrating great promise for compact endoscopic imaging platforms.

Fresnel incoherent correlation holography (FINCH) is a powerful technique for three-dimensional (3D) imaging under spatially incoherent illumination, traditionally implemented using liquid crystal spatial light modulators (LC-SLMs). In this work, we report what we believe to be the first experimental full-field FINCH implementation that uses a digital micromirror device (DMD) as the wavefront modulation element. Unlike phase-only LC-SLMs, DMDs provide binary amplitude modulation, which introduces additional challenges in wavefront encoding and hologram formation. These challenges are addressed using a Lee hologram-based encoding scheme combined with Fourier-domain spatial filtering to generate two correlated object wavefronts required for FINCH. A complete DMD-FINCH system is developed, integrating optical design, mask generation, and numerical reconstruction. The system is experimentally demonstrated using a single-point, standard test objects and multi-point objects located at different depths under pseudo-incoherent illumination generated by a laser and rotating diffuser. The reconstructed results confirm the 3D imaging capability of FINCH with a DMD-based implementation. The proposed approach establishes DMDs as a viable and cost-effective alternative to LC-SLMs for FINCH, enabling high-speed, accessible, and programmable 3D holographic imaging.

The Ince-Gaussian modes form a complete set of solutions to the paraxial wave equation parametrized by an ellipticity parameter ε, enabling a continuous transition between Laguerre- and Hermite-Gaussian modes. While each fixed ε defines an orthogonal basis, modes associated with different ellipticities are not mutually orthogonal, and no explicit transformation between such bases has been reported. Here, we derive the first explicit finite analytical expression to transform between Ince-Gaussian bases of arbitrary ellipticity, enabling direct and experimentally accessible mapping between non-orthogonal structured-light representations. We further demonstrate an experimental implementation using spatial light modulators to perform ellipticity-resolved modal decomposition. This framework introduces ellipticity as a controllable degree of freedom for structured light engineering, enabling new strategies for mode conversion, encoding, and high-dimensional optical information processing.

Engineering optical resilience against atmospheric turbulence is essential for robust free-space photonic technologies. Here, we demonstrate that dual partially coherent Bessel-Vortex beams-with engineered topological charge pairing-exhibit unprecedented control over turbulence-induced scintillation beyond what is achievable with single beams or partial coherence alone. Using a spatial light modulator, we generate single and dual partially coherent Bessel-Vortex beams and propagate them through a laboratory turbulence chamber calibrated to Kolmogorov statistics ([Formula: see text]) over a 0.15m path, corresponding to a 1km atmospheric propagation with equivalent turbulence strength [Formula: see text]. A key technical innovation of this work is the simultaneous encoding of both the Bessel-Vortex phase profile and the Kolmogorov-distributed random phase onto a single hologram displayed on the SLM-enabling real-time generation of partially coherent structured beams without additional optical components. We find that dual-beam configurations with co-signed topological charges show monotonically increasing resilience with charge difference, whereas counter-signed pairs display a pronounced non-monotonic response with minimal resistance at Δm = 8. Most strikingly, beams with equal-magnitude opposite charges (|m₁| = |m₂|) exhibit monotonic degradation in resilience up to order 14-a behavior absent in single-vortex systems. These results establish dual topological charge pairing as a previously unexplored design parameter for turbulence-resilient optical systems, with direct implications for free-space optical communication, quantum information transfer, and high-precision optical manipulation.

Accessing diverse polarization states across the Poincaré sphere via electrical control is highly desirable in optical communications, bio-imaging and quantum information processing, where fast continuous switching, compactness, and ease of integration into photonikic circuits are essential. Layered anisotropic 2D materials enable polarization modulation in a fast and compact manner, thereby overcoming the speed and size limitations of liquid-crystal based spatial light modulators and electro-optic Pockels cell modulators. Here, we report a Fabry-Perot cavity that integrates two cross-aligned black phosphorus layers, with each layer being independently gated to access the inherently two-dimensional range of polarization states across the Poincaré sphere surface. Our heterostructure design predicts electronic access to 86% of the Poincaré sphere at its S-band operating wavelength. We experimentally validate the design by fabricating and testing such a device in reflection, where we demonstrate independent, two-parameter electronic control of the output polarization.

Abstract In the present work, we propose a novel programmable quadriwave lateral shearing interferometry (pQLSI) system using a binary multiplexed phase grating, realized on a spatial light modulator for wavefront sensing. The multiplexed grating pattern is constructed to generate and position all four beams within a single quadrant of the Fourier plane, effectively eliminating the constraints due to zeroth-order component. By tailoring the frequency of the grating pattern, the shear between the quadriwave can be precisely controlled, allowing for optimal shear and the acquisition of high-density two-dimensional (2D) interferograms. The intensity of all four beams is uniformized and the impact of unwanted diffraction orders is minimized by performing an adaptive beam correction. Sensitivity is further enhanced by leveraging higher-order diffraction orders to increase intensity modulation. These advancements result in highly resolved wavefront profiles and improved estimation of both low and higher-order aberrations. Simulation and experimental results validate the feasibility and effectiveness of the proposed pQLSI system.

Spatial light modulators have a wide range of applications in beam generation, wavefront shaping, and holographic display. Due to the finite pixel size, spatial light modulators struggle to achieve a large field of view and high-efficiency modulation in compact optical systems. Metasurfaces have ultrathin profiles and subwavelength spatial sampling capabilities, offering a novel pathway to overcome this problem. This work proposes a hybrid control architecture that enhances scanning range and viewing angle without increasing system volume, where the metasurface is integrated inside a spatial light modulator. The static metasurface performs fine spatial encoding to extend the maximum spatial frequency while the spatial light modulator dynamically refreshes the phase of low-frequency components. By jointly designing the metasurface and the phase retrieval algorithm, single-order diffraction with high fidelity can be achieved. This strategy offers a compact solution for real-time and large field of view modulation, with potential applications in wide-field imaging, glasses-free 3D displays, and human-machine interaction.

Dynamic control of light, particularly beam steering, is essential for applications, such as optical communications, LiDAR, and advanced imaging. Optical metasurfaces composed of subwavelength nanostructures provide a powerful platform for ultrathin wavefront engineering. Here, we demonstrate a compact near-infrared beam-steering device based on CMOS-driven liquid-crystal metasurfaces. From the combination of the Mie resonances of silicon nanoantennas with Fabry-Perot cavity-induced phase accumulation, the device enables continuous phase modulation approaching 2π. Enabled by a CMOS backplane with independently addressable electrodes, the device achieves an ultracompact pixel pitch of 0.8 μm and integrates 2500 independently addressable one-dimensional (1D) electrode arrays. As a result, electrically controlled 1D beam steering with a field of view of up to 24° is achieved. The diffraction efficiency reaches ∼40% at small angles and remains above 18% at the maximum deflection. This scalable, CMOS-compatible architecture provides a promising route toward next-generation spatial light modulators for near-infrared photonics.

Laser-excited volumetric displays render 3D volumetric images by focusing ultrashort laser pulses, whose intense electric fields ionize molecules to generate emission voxels. The image visibility and scale depend on the efficiency of laser excitation. However, generating emission voxels, particularly in the air, requires high pulse energy, making it essential to develop efficient voxel generation techniques to achieve images that can be experienced by users under typical lighting conditions. In this study, we propose a method using an optical pulse shaping system to adjust the temporal profile of femtosecond laser pulses for efficient voxel generation. A genetic algorithm was used to optimize the phase modulation pattern applied to the spatial light modulator, thereby exploring the optimal pulse shape to enhance voxel emission. As a result, a 1.82-fold enhancement in the emission intensity was achieved compared to the unshaped pulse condition.

Raman spectroscopy enables label-free identification of biological tissues, but its clinical application remains limited due to low-throughput measurements. Here, we developed a spatially multiplexed random-access Raman probe that enables simultaneous spectral acquisition from arbitrarily selected locations in vivo. Parallel acquisition of up to 1718 spectra in a single exposure has been enabled by using a custom fiber bundle in combination with a spatial light modulator. In vivo measurement of a peripheral nerve in the abdominal cavity of an anesthetized canine demonstrated the feasibility of the developed system for intraoperative tissue identification within 5 s. We further performed discriminant analysis of multipoint spectra from nerve and non-nerve regions in rats, which achieved 92.5% accuracy and sensitivity for nerve discrimination. The developed system provides a basis for efficient and accurate navigation in surgery.

We propose a dual-path holographic laser rendering system capable of creating centimeter-scale volumetric graphics directly in physical space. The proposed system employs two synchronized optical paths, each consisting of a femtosecond laser combined with a liquid-crystal spatial light modulator, a three-dimensional beam scanning module composed of galvanometer mirrors and a varifocal lens, and an Xe-filled rendering volume. Our dual-path rendering approach, in which each optical path independently forms and cooperatively renders volumetric graphics, has been experimentally demonstrated to produce centimeter-scale volumetric graphics and animations with significantly improved brightness and voxel density. Furthermore, we developed a prototype system and successfully demonstrated it to the general public at SIGGRAPH 2024, providing interactive volumetric graphics with sufficient brightness under normal room lighting conditions, user safety, and intuitive user interaction. These comprehensive design considerations and demonstration outcomes represent a significant step toward the practical realization of laser-excited volumetric displays.

We demonstrate a single-layer, feed-forward free-space optical neural network (ONN) for image classification using a mass-producible micro electromechanical system (MEMS)-based phase light modulator (PLM) to achieve an unprecedented reduction in in-situ model-free training time. Compared to liquid-crystal-based spatial light modulators (LC-SLMs), PLMs have much higher switching speed at lower costs, which is preferable for practical applications. However, the naturally low phase resolution and non-uniform phase quantization of a PLM present challenges in ONN optimization. We demonstrate with an evolutionary strategy that utilizing a discrete distribution offers many benefits over a continuous distribution, which is often used in systems based on LC-SLMs. Compared to a policy with a normal distribution, perturbation with a categorical distribution is less susceptible to the impact of phase quantization, and it follows the behavior of the natural gradient for better convergence as its exploration can be shaped to more efficiently traverse the action-space. Thus, despite the non-uniformity of phase quantization intrinsic to the PLM, our testbed achieved comparable performance to the reported ONN based on LC-SLMs of the same dataset size, but with approximately 10-fold reduction of in-situ training time. This increased speed is critically important for many practical applications, especially for systems in uncontrolled environments. We systemically investigated the impact of phase quantization levels on ONN performance. We show that the exploration of discrete categorical policy is less affected by the number of phase levels, maintaining good performance under coarse quantization. In contrast, the ONN performance of a continuous normal policy can be severely penalized with the reduction of quantization levels because of the reduced exploration and slower convergence.

This study examines the influence of relative motion-induced angular deviations on fiber coupling and communication performance in high-speed coherent free-space optical systems. Simulations reveal that higher-order modes experience a steeper drop in coupling efficiency than the fundamental mode as the incident angle grows. Using a spatial light modulator (SLM) and fast steering mirror (FSM) to generate higher-order linearly polarized (LP) modes and emulate angular tilt, the coupling behavior was experimentally validated. Within 0-1.2 mrad deflection, the LP01 mode's bit error rate (BER) increased from 4.978 × 10-13 to 1.302 × 10-6, accompanied by an error vector magnitude (EVM) rise from 8.65% to 10.73%. In comparison, the LP31 and LP03 modes reached EVMs of 11.89% and 16.92%, respectively, underscoring their heightened sensitivity to angular misalignment. These findings underscore the critical role of mode selection and tolerance design in high-capacity spatial optical receivers under angular mismatch.

We propose a protocol for efficient synthesis of vector-twisted beams with higher-order Poincaré polarization states via the random vector-mode decomposition method, where the polarization state and twist phase information are encoded into the deterministic and random complex amplitude parts of vector modes, respectively. Further, a compact vector-twisted beam generation system involving a phase-only spatial light modulator and a common-path interferometer is established. Multiple types of vector-twisted beams are successfully synthesized, and their propagation properties, including intensity, polarization state, and degree of polarization, are investigated in detail. Our results reveal that the twist phase can induce the local spin angular momentum splitting or redistribution and resist the coherence-induced depolarization during beam propagation, offering what we believe to be a new degree of freedom to modulate polarization in random vector beams.