Fushi Zhang

Improvement of volume holographic performance by plasmon-induced holographic absorption grating

We report on the enhanced holographic performance by employing a strong volume holographic absorption grating induced by localized surface plasmon resonance effect in a bulk gold nanoparticles doped photopolymer. The contributions of plasmon-induced volume holographic absorption grating is characterized through the Kogelniks coupled wave model and demonstrated experimentally by using two-beam interference technology. At the 0.05 vol. % concentration of the gold nanoparticles in the bulk photopolymer, 101.8% increase in the diffraction efficiency and more than four times suppression of the first side lobe in angular selectivity have been achieved.

Domain structure evolution and fatigue cracking of ⟨001⟩-oriented [Pb(Mg1∕3Nb2∕3)O3]0.67(PbTiO3)0.33 ferroelectric single crystals under cyclic electric loading

The authors report on the electrically induced fatigue cracking and phase transition behavior for ⟨001⟩-oriented [Pb(Mg1∕3Nb2∕3)O3]0.67(PbTiO3)0.33 (PMN-PT 67∕33) ferroelectric single crystals under cyclic electric field. For crystals with initial cracks, crack growth and deviation are associated with the transition from the rhombohedral to the tetragonal phase, even though the peak value of the applied cyclic electric field is below the coercive field (Ec). For crystals without initial cracks, numerous microcracks are developed in the crystal as a result of 71° domain switching.

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...

In-Situ Observation of Electrically Induced Fatigue Crack Growth for Ferroelectric Single Crystals

In-situ observation of electrically induced fatigue crack growth was carried out for ferroelectric single crystals under alternative electric field. Electrically-induced fatigue crack growth was observed both below and above the coercive field. The crack propagation behavior is a repeated process of a continuous increment followed by a sudden increase in the crack length. This jumped crack growth behavior was attributed to the variation of the crack boundary conditions under electric field cycling.

Three-dimensional display based on refreshable volume holograms in photochromic diarylethene polymer

Holographic display is a promising technique for three-dimensional (3D) display because it has the ability to reconstruct both the intensity and wavefront of a 3D object. Real-time holographic display has been demonstrated in photorefractive polymers. It is expected to carry out dynamic 3D display by recording holograms into a volume holographic polymer due to its high-density storage capacity, good multiplexing property. In this work an updatable 3D display based on volume holographic polymer of photochromic diarylethene is proposed. The photochromic diarylethene polymer is a promising rewritable recording material for holograms with high resolution, fatigue resistance and quick responding of erasure. The computer-generated holograms carrying with wavefronts of 3D objects are written to the diarylethene polymer, and the recorded holograms in the polymer can be easily erased when exposed in ultraviolet light. The 3D scenes can be reconstructed for the write/erase cycles.

Electric-Field Induced Fatigue Crack Growth in Ferroelectric Single Crystals

As one important class of the functional materials, ferroelectrics have been widely used as sensors, actuators, and transducers in smart structures. However, due to a strong electro-mechanical coupling, ferroelectrics suffer rather high stress under cyclic electric field. The low fracture toughness (lower than 1MPa·√m) and large switching strain render the reliability issue a bottleneck for the performance against crack propagation of ferroelectrics in smart structures. The importance for the reliability of ferroelectric materials gives a strong impetus for the studies on the crack propagation and the underlying mechanisms [1, 2, 3, 4, 5, 6, 7, 8, 9]. As fatigue crack growth in ferroelectric ceramics is often related with the grain boundary effects, a systematic study using single crystals is warranted for a better understanding of the electric-field-induced fatigue crack growth and its close relationship with the 90° domain switching.