Zhu Yongyuan

Red and Blue Light Generation in an LiTaO3 Crystal with a Double Grating Domain Structure

The Pd39Ni10Cu30P21 bulk metallic glass is isothermally relaxed under various pressures. The degree of the structural relaxation is evaluated in terms of the enthalpy recovery behaviours involved in the irreversible glass transition processes by using a temperature-modulated differential scanning calorimetry technique. A roughly Linear increase of the recovery enthalpy is observed within the experimental pressure range fi-om 2.67 to 4.45 GPa, which reflects the release of the frozen-in enthalpy in the as-quenched glass with increasing relaxation pressure. The pressure dependence of the timescale of the enthalpy recovery processes is also exhibited.

Single Pass Third-Harmonic Generation of 310 mW of 355 nm with an All-Solid-State Laser

A maximum of 310 mW average output power at 355 nm has been obtained by extracavity frequency tripling with a BBO crystal in a Q-switched Nd:YVO4 laser with 11.2 W of laser diode pump power. The single pass frequency conversion efficiency (infrared-to-ultraviolet) is 14.3%. The power stability of the ultraviolet laser is better than 1% in 30 min.

Observation of Optical Bistability in Two-Dimensional Volume Refractive Index Grating Thermally Fixed in LiNbO3:Fe Crystal

Experimental observation of optical bistability in a nonlinear two-dimensional volume refractive index grating is reported. The index grating in LiNbO3: 0.1 wt.% Fe photorefractive single crystal was fabricated by using hologram recording and subsequent thermal fixing techniques. Due to the thermal fixing, the stored 2D volume index grating shows no optical erasure during readout. An explanation of the nonlinear phenomena is also given in terms of the intensity-enhanced bulk photovoltaic effects in LiNbO3:Fe material.

Efficient Generation of Red and Blue Light in a Dual-Structure Periodically Poled LiTaO3 Crystal

We demonstrate the efficient generation of red light at 671 nm and blue light at 447 nm from a diode-pumped Q-switched 1342 nm Nd:YVO4 laser together with a periodically poled LiTaO3 (PPLT) crystal. The sample used in this experiment is a dual-structure PPLT crystal with the period of 14.9 μm for the second harmonic generation and that of 4.9 μm for the third harmonic generation. The red and blue light, with the respective average power of 752 mW and 153 mW were obtained in a single path under an average fundamental power of 1.74 W, corresponding to the conversion efficiencies of 43.2% and 8.8%, respectively. These results indicate that the dual-structure PPLT can be used to construct a compact and efficient all-solid-state red-and-blue dual-wavelength laser.

Strong Coupling of a Meta-Diatom to a Plasmonic Nanocavity

A strong coupling meta-diatom-plasmonic nanocavity is proposed and numerically investigated. When the meta-diatomic sizes are gradually increased, the meta-diatomic electric dipole and quadrupole resonances could strongly couple to those of the nanocavity. The characteristic anticrossing behaviors of three hybrid modes manifest the occurrence of the strong coupling from the transmission spectra, with Rabi-type splittings at about 40.8 meV and 128.4 meV for dipole interaction, and 11.8 meV and 72.7 meV for quadrupole interaction, respectively. We also present the coupling strength dependence on meta-atomic positions, in which one meta-atomic position is fixed and the other is changed. The average Rabi-type splittings of three polariton modes are used to evaluate the coupling strength of the meta-atomic position dependence. The corresponding Rabi-type oscillation in the time domain is also presented, which is obviously different from the one of a single meta-atom strongly coupling to a nanocavity.

(2+1)-Dimensional Envelope Solitons in Nonlinear Magnetic Metamaterials *

The dynamics of nonlinear magnetoinductive waves in a two-dimensional monoatomic lattice of Split ring resonators (SRRs) with Kerr nonlinear interaction between nearest neighbors is studied analytically. The soliton excitation genuine of the discreteness and nonlinearity in such a system based on an extended quasidiscreteness approach are obtained.

Plasmon-Assisted Phase-Matched Second- and Third-Harmonic Generation in Single-Negative Heterostructures

Dispersion relations of surface plasmon polaritons (SPPs) in sandwiched optical systems are studied. The system is actually a kind of SPP waveguides, with two kinds of single negative material (SNG) as core and cladding layers, respectively. Since both TM and TE polarized SPPs can be excited in the structure, the dispersion of SPPs becomes more abundant and leads to colorful nonlinear optical properties. The authors demonstrate the effective phase-matched second and third-harmonic generation (SHG, THG) assisted by the coupled SPPs. A cascaded second-order nonlinear process can also be achieved in the structure when the thickness of the core layer is properly selected, leading to the simultaneous SHG and THG. Further investigations show that much easier phase-matching can be fulfilled in the SNG waveguide array. Our results would be of potential use for surface-enhanced frequency conversion device such as light emitters or lasers.

Engineered ferroelectric superlattice materials and applications

The study of superlattice based on ferroelectric crystal has made a rapid progress since 1980s. The superlattice is composed of modulated domains on the micron scale controllable with modern techniques. A lot of new phenomena have been techniques for fabrication and characterization, and in exploring new physical effects for the nonlinear-optical applications.

Direct Observation of Domain-Inverted Regions in Proton-Exchanged LiNbO3 Using Transmission Electron Microscopy

Direct observation of the domain-inverted regions in LiNbO3 formed by proton exchange followed by heat treatment is performed by using transmission electron microscopy. A charged straight 180° twinning domain boundary was revealed and compared with winding domain boundaries in LiNbO3 grown by Czochralski method. Obtained results are significant to studying the mechanism of domain inversion and morphology of inversion domains.