This article demonstrates theoretical design of ultracompact all-optical AND, NAND, OR, and NOR gates with two-dimensional nonlinear photonic crystal slabs. Compound Ag-polymer film with a low refractive index and large third-order nonlinearity is adopted as our nonlinear material and photonic crystal cavities with a relatively high quality factor of about 2000 is designed on this polymer slab. Numerical simulations show that all-optical logic gates with low pump-power in the order of tens of MW/cm² can be achieved. These design results may provide very useful schemes and approaches for the realization of all-optical logic gates with low-cost, low-pump-power, high-contrast and ultrafast response-time.

In this article, a novel method of holographic imaging with Au nanoantenna array is presented. In order to obtain the plasmonic holographic plate for a preset letter “NANO”, the phase distribution of the hologram is firstly generated by the weighted Gerchberg-Saxton (GSW) algorithm, and then 16 kinds of V-shaped nanoantennas with different geometric parameters are designed to evenly cover the phase shift of 0 to 2π by finite-difference time-domain (FDTD) method. Through orienting these nanoantennas according to the phase distribution of the hologram, the plasmonic array hologram is obtained. Very good imaging quality is observed with our nanoantenna array hologram plate. This method can be used for holographic imaging of arbitrary shape, and may find potential applications in holographic memory, printing and holographic display.

An ultrafast all-optical switching with the response time on the order of 10 fs is demonstrated in a three-dimensional opal polystyrene nonlinear photonic crystal by means of precise femtosecond pump-probe technique. The switching is realized by the shift in the photonic band gap under external optical pumping of 8 fs Ti:sapphire pulse laser with a peak pump power of 20.6 GW/cm2. The good performance of optical switching is attributed to the very strong and fast Kerr nonlinear optical response of the polystyrene material.

Fibre surface-enhanced Raman scattering (SERS) probes have the advantages of flexibility, compactness, remote sensing capability and good repeatability in SERS detection and thus have a range of different applications. However, it is difficult to realize simple, low-cost and high-throughput preparations of fibre SERS probes with high sensitivity and desirable repeatability using the currently available fabrication techniques, which restricts their practical applications. We report here a simple, low-cost method using laser-induced self-assembly to realize the fast fabrication of fibre SERS probes with high sensitivity and excellent reproducibility. By lifting the fibre facet above a pre-synthesized nanoparticle colloid, a meniscus can be formed with the help of the surface tension of the liquid. Using irradiation from an induced laser guided by the fibre, localized thermal effects on the nanoparticles in the meniscus control the growth of the fibre probes and the electromagnetic interactions among the closely spaced nanoparticles assist the arrangement of nanoparticle clusters on the fibre facet. The prepared fibre probes showed a very high SERS sensitivity of 10⁻¹⁰ M for p-aminothiophenol using a portable commericial Raman spectrometer with a short integration time of 2 s. They also showed excellent repeatability with relative standard deviations <2.8% in the SERS peak intensities for different detections with the same probe and 7.8% for different fibre probes fabricated under the same conditions.