Song Zong

Enhanced diffraction efficiency of mixed volume gratings with nanorod dopants in polymeric nanocomposite

We propose a method to improve the holographic performance of a volume holographic material by the particle-shape dependence of doped nanoparticles. Previously reported methods are based on changing the doping concentration of dopants and the diameter of nanoparticles or modifying the surface of nanoparticles. When transverse surface plasmon resonance of optimized gold nanorods shifts near the recording wavelength, experiments confirmed that enhancement of diffraction efficiency by efficient dopants of gold nanorods is better than that of gold nanospheres. The enhancement effects under optimal mixing conditions occur with a crucial factor of maximum absorption intensity at the recording wavelength using the particle-shape dependence of doping nanorods. The gold nanorods with an average diameter of 10 ± 2.1 nm and an average length of 34 ± 5 nm are doped in Phenanthrenequinone-doped poly(methyl methacrylate) photopolymers. The diffraction efficiency of volume holographic grating in the photopolymer doped w...

Multilayer volume holographic optical memory with reduced crosstalk (Conference Presentation)

Holographic data storage is expected to realize capacity of terabytes as well as fast data-transfer rate of Gbits/sec on a disk format. This kind of performance will be a potential solution for next-generation storage of big data in diversities of applications such as cloud servers and ultra-high definition systems. In this work, we analyze and optimize the axial response of the holographic data storage, aiming at maximizing storage density while suppressing the inter-page crosstalk on the reconstructed data pages. The optical model of the three dimensional hologram recorded in the medium is presented. Based on the reconstructed data page model, inter-layer crosstalk is also analyzed by use of orthogonal reference patterns. The signal to noise ratio and bit error rate of the reconstructed data page are improved. Experiments are conducted to obtain the axial shift selectivity curves and verify the predicted storage density and capacity of a holographic optical disk.

Improvements of volume holographic grating in photopolymer doped with nanorods(Conference Presentation) (Withdrawal Notice)

Enhanced volume holographic refractive index grating by employing a strong volume holographic absorption grating induced by the periodic spatial distribution of gold nanoparticles due to the polymerization-driven multicomponent diffusion in a bulk gold nanoparticles doped photopolymer is noticeable. Till now most works are only focused on changing the concentration of nanoparticles and the radius of sphere nanoparticles. We propose an approach to improve the volume holographic grating by changing the size and shape of doped nanoparticles. The difference between nanorods and nanospheres is analyzed by the finite difference time domain(FDTD) method and the holographic kinetic model. The simulation results indicate that the nanorods has stronger localized surface plasmon resonance effect. The size and the aspect ratio of gold nanorods are optimized for the best absorption at a certain wavelength of recording light. The experiment results verify that the nanoparticles can be designed to achieve higher diffraction efficiency in a mixed volume holographic grating.

Characteristics of gold nanorods in volume holographic nanocomposites

Gold nanorod has generated great research interests due to its tunable surface plasmon resonance (SPR). The mechanism of the SPR effect on the enhancements of optical performance for the volume holographic polymer is investigated. The resonance wavelength is dependent on the aspect ratio of the nanorod. Theoretical model for the localized surface plasmon resonance effect are developed and simulated for the interactions between the photopolymer components and nanorods in the gold nanorod doped volume holographic photopolymer. The experimental evaluation of the material suggests a novel candidate for potential applications in high-density optical data storage and high-resolution holographic display.

Complex wavefront modulation and holographic display using single spatial light modulator

A holographic display method based on complex wavefront modulation using single spatial light modulator is proposed. The holographic display is achieved from complex wavefront encoded by double phase hologram. The modulated beam by single phase-only spatial light modulator passes through a 4f optical system to synthesize the expected complex modulated wavefront on the output plane, with a low-pass filter in the Fourier plane. The performance of holographic display is also improved by complex wavefront modulation, compared with the holographic display based on phase-only wavefront modulation. The proposed encoding and display technique is theoretically demonstrated, as well as validated in numerical simulations.

Temperature tolerance analysis on the volume holographic data storage (Conference Presentation)

Publishers Note: This conference presentation was withdrawn 15 January 2018 per author request.

Layer-oriented computer-generated holograms for three-dimensional display

Depth cues and full-parallax are crucial issues in the calculation of computer-generated holograms (CGHs) for perfect holographic three-dimensional (3-D) display. In order to accelerate the speed of generating CGHs and improve the display quality, three layer-oriented methods are investigated in this paper. The first method is based on angularspectrum, which can provide accurate depth cues. The second method is based on inverse Fresnel diffraction layered holographic stereogram to provide accurate depth information as well as correct occlusion effect. The third method is proposed to generate zoomable 3-D CGHs using layer-based shifted Fresnel diffraction. Numerical simulations and optical experiments have demonstrated that the proposed methods can reconstruct quality 3-D images.

Zoomable three-dimensional computer-generated holographic display based on shifted Fresnel diffraction

We present a technique for generating zoomable three-dimensional (3-D) computer-generated holograms (CGHs) using layer-based shifted Fresnel diffraction. The 3-D scene is sliced into multiple parallel layers according to the depth information. Shifted Fresnel diffraction is implemented in calculating the propagations from different layers to the hologram plane with adjustable sampling rates. The proposed method provides an efficient way for zooming 3-D CGHs without optical zoom module. Optical experiments have been performed, which demonstrate the proposed method can reconstruct quality 3-D images with different scale factors.

Resampling masks for phase-shifting digital holography

Holographic imaging is degraded severely by the speckle or incoherent noise. In this work, resampling mask method based on phase-shifting digital holography is proposed to reduce the reconstruction noise. The zero-order and the conjugate term of the hologram can be eliminated with four-step phase-shifting digital holography (PSDH). The complex amplitude of the object after propagation can be calculated by the phase-shifting algorithm. A phase-only spatial light modulator is used to realize PSDH in the experiment. The complex amplitude is encoded into several parts by resampling masks. A high quality reconstruction image with low noise is achieved through the superposition of the individually reconstruction of coded complex amplitudes. The experiment data go well with the asymptotic function. This method can be used for digital holographic imaging of the biological samples and microstructures. Experimental results prove the feasibility of this proposed method.

Noise reduction for compressive digital one-shot in-line holographic tomography

Digital holography can reconstruct 3-D data cube from a 2-D hologram for the tomographic imaging. Digital one-shot inline holography (DOIH) maintains the maximal space-bandwidth product compared with off-axis holography and keeps both amplitude and phase in the interference pattern. DOIH often suffers from intrinsic defects such as twin-image interruption and squared noise. In this work, compressive sensing is applied in the tomographic reconstruction to overcome the defects. The designed algorithm based on compressive DOIH demonstrates the feasibility in removing the squared noise from a single 2-D in-line hologram.