Junxue Chen

Preparation and photoluminescence of alumina membranes with ordered pore arrays

Porous alumina membranes with ordered pore arrays were prepared electrochemically from Al metal in C2H2O4 or H2SO4. Photoluminescence (PL) measurements show that a blue PL band occurs in the wavelength range of 400–600 nm. This band originates from singly ionized oxygen vacancies (F+ centers) in porous alumina membranes. Tentative reasons for the changes in intensity and peak position of the PL band with increasing heat-treatment temperature are discussed.

Surface plasmon resonance hydrogen sensor based on metallic grating with high sensitivity

High sensitivity is obtained at larger resonant incident angle if negative diffraction order of metallic grating is used to excite the surface plasmon. A highly sensitive grating-based surface plasmon resonance (SPR) sensor is designed for the hydrogen detection. A thin palladium (Pd) film deposited on the grating surface is used as transducer. The influences of grating period and the thickness of Pd on the performance of sensor are investigated using rigorous coupled-wave analysis (RCWA) method. The sensitivity as well as the width of the SPR curves and reflective amplitude is considered simultaneously for designing the grating-based SPR hydrogen sensor, and a set of optimized structural parameters is presented. The performance of grating-based SPR sensor is also compared with that of conventional prism-based SPR sensor.

PLASMONIC EIT-LIKE SWITCHING IN BRIGHT-DARK-BRIGHT PLASMON RESONATORS

In this paper we report the study of the electromagnetically induced transparency (EIT)-like transmission in the bright-dark-bright plasmon resonators. It is demonstrated that the interferences between the dark plasmons excited by two bright plasmon resonators can be controlled by the incident light polarization. The constructive interference strengthens the coupling between the bright and dark resonators, leading to a more prominent EIT-like transparency window of the metamaterial. In contrary, destructive interference suppresses the coupling between the bright and dark resonators, destroying the interference pathway that forms the EIT-like transmission. Based on this observation, the plasmonic EIT switching can be realized by changing the polarization of incident light. This phenomenon may find applications in optical switching and plasmon-based information processing.

Growth and polarization features of highly (100) oriented Pb(Zr0.53Ti0.47)O3 films on Si with ultrathin SiO2 buffer layer

Highly (100) oriented Pb(Zr0.53Ti0.47)O3 (PZT) films were prepared on Si substrates with ultrathin SiO2 buffer layer by pulsed laser deposition. Hysteresis measurements show that saturation polarization, remnant polarization and coercive field of the films reach 26 μC/cm2, 10 μC/cm2 and 70 kV/cm, respectively. The thickness of SiO2 buffer layer is found to play a significant role on phase purity and orientation of PZT as well as the prevention of interdiffusion. It is also found that the grain size and the interdiffusion between PZT and Si are the key factors for the ferroelectric properties of the films, which are discussed together with the synthesis condition in detail.

Optical bistability enhanced by highly localized bulk plasmon polariton modes in subwavelength metal-nonlinear dielectric multilayer structure

Optical bistability of subwavelength metal-nonlinear dielectric multilayer structure is numerically studied in this letter. It is found that very low intensity thresholds for optical bistability can be achieved due to the excitation of highly localized bulk plasmon polariton modes with TM polarized illumination. A bistability threshold of 6.9 MW/cm2 is obtained for BPP0 mode, which is much lower than the recently reported results based on the large local field enhancement at the band edge of metal-dielectric photonic band gap structure [A. Husakou and J. Herrmann, Phys. Rev. Lett. 99, 127402 (2007)].

ASYMMETRY IN THE HYSTERESIS LOOP OF PB(ZR0.53TI0.47)O3/SIO2/SI STRUCTURES

The integrated ferroelectric/semiconductor systems, Pb(Zr0.53Ti0.47)O3 (PZT)/SiO2/Si have been prepared and investigated. It was found that an asymmetry related to the conduction type of the substrate (Si) and the polarization direction of PZT exists in the polarization–voltage loops of the integrated system. According to the configuration and the characteristic of the integrated structure, we suggest that the space charge layer in Si and the tunneling process between Si and PZT during the polarization are the main causes for this asymmetry.

Optical bistability effect in plasmonic racetrack resonator with high extinction ratio

In this paper, optical bistability effect in an ultracompact plasmonic racetrack resonator with nonlinear optical Kerr medium is investigated both analytically and numerically. The properties of optical bistability and pump threshold are studied at 1.55 µm with various detuning parameters by an analytical model. The transmission switch from the upper branch to the lower branch with a pulse is also demonstrated by a finite-difference time-domain method. An extinction ratio of 97.8% and a switching time of 0.38 ps can be achieved with proper detuning parameter. Such a plasmonic resonator design provides a promising realization for highly effective optical modulators and switch.

Plasmonic racetrack resonator with high extinction ratio under critical coupling condition

In this paper, an ultracompact plasmonic racetrack resonator based on single mode metal-insulator-metal plasmonic gap waveguide with high coupling efficiency is investigated both analytically and numerically. The coupling properties of a plasmonic waveguide to a racetrack resonator at 1.55 μm wavelength are studied with various coupling lengths. An extinction ratio of −34.5 dB and a free-spectral range of 303 nm at the critical coupling point can be achieved. Such a plasmonic resonator design provides a promising realization for highly effective modulators and wide band filters.

Theoretical and experimental studies of surface plasmons excited at metal-uniaxial dielectric interface

In this letter, surface plasmons (SPs) excited at the metal-uniaxial dielectric interface are investigated both theoretically and experimentally. The dispersion relations of SPs are derived for the cases where the optical axis of uniaxial medium is parallel the interface or in the incident plane perpendicular to the interface. The theoretical predictions are verified by a Kretschmann–Raether [W. L. Barnes, A. Dereux, and T. W. Ebbesen, Nature (London) 424, 824 (2003)] configuration with azobenzene polymer as photoinduced uniaxial medium. The attenuated total reflection spectra clearly show that the dependence of the SPs propagation properties on the orientations of optical axis, which is consistent with the theoretical analysis. The results of this study provide a useful approach to modulate SPs through adjusting the azobenzene molecular orientation.

Bloch surface waves confined in one dimension with a single polymeric nanofibre

Polymeric fibres with small radii (such as ≤125 nm) are delicate to handle and should be laid down on a solid substrate to obtain practical devices. However, placing these nanofibres on commonly used glass substrates prevents them from guiding light. In this study, we numerically and experimentally demonstrate that when the nanofibre is placed on a suitable dielectric multilayer, it supports a guided mode, a Bloch surface wave (BSW) confined in one dimension. The physical origin of this new mode is discussed in comparison with the typical two-dimensional BSW mode. Polymeric nanofibres are easily fabricated to contain fluorophores, which make the dielectric nanofibre and multilayer configuration suitable for developing a large range of new nanometric scale devices, such as processor–memory interconnections, devices with sensitivity to target analytes, incident polarization and multi-colour BSW modes.