Boaz Jessie Jackin

This study proposes an efficient ray-tracing method for hologram data computation to reconstruct three-dimensional images with realistic shading and occlusion. Local Fresnel zone plates are generated by modulating their amplitudes using luminance obtained from backward ray tracing. For each point light source, rays are traced at a constant sample count regardless of depth, and the resulting luminance data are mapped onto the hologram plane using bilinear interpolation. Optical reconstruction experiments demonstrate that limiting the number of rays shortens ray-tracing time while successfully reconstructing images with smooth shading and occlusion.

Understanding the energetic disorder in polymeric organic semiconductors is critical for optimizing their charge transport properties in photoconductive and optoelectronic devices. In this study, we systematically investigated the influence of molecular weight on the density of states (DOS) and photorefractive (PR) performance of poly(N‐vinylcarbazole) (PVCz)‐based composites. Photoelectron yield spectroscopy (PYS) revealed that the energetic disorder, characterized by the deviation of the DOS ( σ _DOS ), decreases with increasing PVCz molecular weight, despite the HOMO energy level remaining constant. Photorefractive performances showed that diffraction efficiency increases and response time decreases with increasing molecular weight, exhibiting a strong correlation with σ _DOS . Thermal and structural characterizations—including glass transition temperature ( T _g ), X‐ray diffraction (XRD), density ( ρ ), and fractional free volume (FFV)—demonstrated that σ _DOS is most strongly correlated with T _g (R ² = 0.931), suggesting that chain rigidity and packing density are key factors influencing energetic disorder. The Gaussian disorder model (GDM) was applied to estimate carrier mobility, further validating the DOS‐derived transport trends. This work establishes T _g as a practical and predictive proxy for σ _DOS , offering a simple and effective approach for evaluating energetic disorder in polymeric semiconductors. Our findings provide a framework for the rational design of PR materials and extend to broader applications in organic electronics.

Azobenzene-based hologram recording materials are well known for their rewritable and polarization-selective properties that enable polarization-multiplexed recording and high-density optical storage. High diffraction efficiency, longer retention time, and shorter response time are desirable for rewritable recording materials, but they always require a trade-off relationship. In this study, we show that by simply coating the Azobenzene-based film with multiple layers of a suitable material, these parameters can be improved simultaneously without compromise. Bilayer films and triple layer films were prepared by depositing a DNA–surfactant complex-based layer above and below the azobenzene-based poly(CACzE-MMA) copolymer layer. The hologram recording performance was evaluated in terms of the diffraction efficiency, photoresponse time, and retention behavior of the recorded gratings. Compared with monolayer copolymer films, the multilayer DNA–surfactant complex-based copolymer films exhibited enhanced diffraction efficiency and faster photoresponse. In particular, the bilayer and trilayer structures showed a marked improvement in retention time, indicating suppressed relaxation of refractive index modulation. This enhancement is attributed to molecular confinement at the DNA–surfactant complex and copolymer interfaces generated by the layered architecture. These results demonstrate that a DNA–surfactant complex-based layering approach is an effective strategy for improving hologram stability and highlight the potential of DNA–surfactant complex-derived matrices as effective alternatives to poly(methyl methacrylate) (PMMA) in holographic applications.

The miniaturization of silicon-based electronics is reaching its fundamental limitations, necessitating the search for alternative computational paradigms. One of the promising directions is to consider inherently nonlinear dynamic systems for computing operations, instead of the linear von Neumann system. This approach requires the system to exhibit rich and controllable nonlinear dynamic behavior that is highly suitable for modern machine learning operations. Here, what we believe is for the first time, we experimentally demonstrate controllable and sustainable nonlinear dynamic behavior exhibited by a simple photorefractive two-wave mixing setup (PR-TWM) without any external feedback. The novel idea used here is to apply a sinusoidal electric field across the photorefractive sample in the two-wave mixing (TWM) process. As a result, a period-doubling type of nonlinear dynamic behavior was observed, which was then systematically analyzed using phase-space plots, attractor dimension calculation, bifurcation plots, and Lyapunov exponent values. Our findings demonstrate a direct correlation between applied field strength and the attractor dimension, highlighting a controllable nonlinear dynamical behavior. Such a simple system with controllable complex nonlinear dynamic behavior has potential to be utilized in the field of nonlinear dynamics-based computing paradigms such as reservoir computing, neuromorphic computing, in-materio computing, analog computing, etc.

We present a novel, to the best of our knowledge, method for generating vector-vortex beams through linear polarization multiplexing of intensity and polarization holograms. Utilizing the rewritable properties of an azo-carbazole polymer film, we experimentally demonstrate the simultaneous generation of two distinct vector-vortex beams from the first-order diffraction of the single hologram using a triple-exposure recording technique. This approach enables the selective generation of vector-vortex beams by utilizing different reconstruction effects like FRE, ORE, or NRE and by simply adjusting the polarization state of the reading beam. This method significantly simplifies the generation of multiple vector-vortex beams and offers promising potential for applications in optical communication and encryption.

The photorefractive (PR) performances, photoconductivity, and transient dynamics of photocurrent are investigated for poly[ N , N ’‐bis(4‐butylphenyl)‐ N , N ’‐bis(phenyl)‐benzidine] (poly‐TPD)‐based PR composites. Plasticizer and sensitizer are benzyl butyl phthalate (BBP) and [6,6]‐phenyl C ₆₁ butyric acid‐methyl ester (PCBM), respectively. Five different types of amino‐styrene‐based NLO dyes are compared from compatibility and PR performance points of view. The proper choice of NLO dye is 4‐azacycloheptylbenzylidene malononitrile (7‐DCST). The electric field E and the illumination wavelength dependences of the diffraction efficiency η and the response time τ _η are investigated. η of 6.85% with τ _η of 3.8 ms and optical gain of 42.3 cm ⁻¹ are measured at 532 nm with E = 80 V µm ⁻¹ for poly‐TPD/7‐DCST/BBP/PCBM. The saturation space‐charge field, the effective number density of traps, the space‐charge field, and the PR phase shift are evaluated. The time for trapping directly evaluated from the photoconductivity is significantly related to τ _η . The simulation of the transient dynamics of photocurrent reproduced well the shallow trapping at earlier time regions, followed by the deep trapping at later times, which is well correlated to the growth of η . The origin of the shallow and deep traps is discussed.

Optical vortices, carried by light beams, are of significant interest due to their intrinsic properties, such as orbital angular momentum and unbounded topological charge, making them valuable for numerous applications. However, conventional methods for generating and detecting these beams often rely on bulky optical setups or complex material fabrication. In this paper, we present a simple and efficient approach for the simultaneous detection of multiple vortex beams. By digitally printing computer-generated holograms on an azo-carbazole polymer film, we generate multiple collinearly superposed optical vortex beams of arbitrary topological charge. Then, we detect the individual topological charges from the superposed beam by employing a second computer-generated hologram. The second hologram diffracts each individual vortex beam to a predefined spatial position, and the individual topological charges can be determined by detecting these positions. We show the simultaneous detection of up to three vortex beams using a straightforward and compact arrangement. This technique offers an accessible solution for potential use in optical encryption, storage, and communication technologies.

Polarization holography has emerged as a promising technique for high-density data storage, security, and optical communication applications.

Optical vortices, carried by light beams, are of significant interest due to their intrinsic properties, such as orbital angular momentum and unbounded topological charge, making them valuable for numerous applications. However, conventional methods for generating and detecting these beams often rely on bulky optical setups or complex material fabrication. In this paper, we present a simple and efficient approach for the simultaneous detection of multiple vortex beams. By digitally printing computer-generated holograms on an azo-carbazole polymer film, we generate multiple collinearly superposed optical vortex beams of arbitrary topological charge. Then, we detect the individual topological charges from the superposed beam by employing a second computer-generated hologram. The second hologram diffracts each individual vortex beam to a pre-defined spatial position, and the individual topological charges can be determined by detecting these positions. We show the simultaneous detection of up to three vortex beams using a straightforward and compact arrangement. This technique offers an accessible solution for potential use in optical encryption, storage, and communication technologies.