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.

This paper describes a facile method of preparing cubic Au nanoframes with open structures via the galvanic replacement reaction between Ag nanocubes and AuCl₂ ⁻. A mechanistic study of the reaction revealed that the formation of Au nanoframes relies on the diffusion of both Au and Ag atoms. The effect of the edge length and ridge thickness of the nanoframes on the localized surface plasmon resonance peak was explored by a combination of discrete dipole approximation calculations and single nanoparticle spectroscopy. With their hollow and open structures, the Au nanoframes represent a novel class of substrates for applications including surface plasmonics and surface-enhanced Raman scattering.