Haifeng Shao

Silicon mode multi/demultiplexer based on multimode grating-assisted couplers

A simple and low-crosstalk 1 × 4 silicon mode (de)multiplexer based on multimode grating-assisted-couplers is proposed. Mode transitions can be flexibly controlled by designing the grating period at the phase-matching condition. Due to the contra-directional coupling, precise control of the coupling strength and the coupling length are not needed in the system. Calculation results show that the insertion loss and the 3 dB bandwidths of the device are 0.2 dB and 3.7 nm, 0.34 dB and 7.6 nm, and 0.21 dB and 11.8 nm for the channels which (de)multiplex to the 1st, 2nd, and 3rd modes of the bus waveguide, respectively.

The cooperative effect of calcium ions and tartrate ions on the corrosion inhibition of pure aluminum in an alkaline solution

Abstract The cooperative effect of calcium ion and tartrate ion on the corrosion inhibition of pure aluminum in an alkaline solution was investigated by hydrogen collection, electrochemical methods and XPS. The results of electrochemical experiments showed that the inhibition of calcium ion was enhanced by the addition of tartrate ion, while tartrate ion itself has only a little inhibition effect. Analysis by XPS, it was found that calcium and tartrate ions did not contribute to the formation of the surface film on aluminum. This fact indicates that these two ions act as interface inhibitor rather than inter-phase one. The cooperative effect of the two ions might be due to formation of complex, which makes it easier for Ca2+ to adsorb on the aluminum surface.

Electrochemical impedance spectroscopy analysis on the electrochemical dissolution of aluminum in an alkaline solution

The process of electrochemical dissolution of aluminum in an alkaline solution was investigated by electrochemical impedance spectroscopy (EIS). A model based on its reaction mechanism was proposed. The kinetic parameters including rate constants of each step and covering densities of intermediates were obtained. The EIS was well analyzed by this model.

Performance influence of FCA and nonlinear FCD to the Mach-Zehnder-Interference based silicon DPSK generation

Silicon unique modulation mechanism based on free-carrier dispersion (FCD) effect determines that there is operation and performance difference from LiNbO(3) modulator when achieving various optical modulation formats. In this paper, the influence of nonlinear FCD and free carrier absorption (FCA) effect on the return-to-zero (RZ)-DPSK generation scheme is numerically analyzed. Silicon waveguide with p-n diode is adopted and the reverse bias is the key factor which should be chosen carefully. Performance analysis includes two parts: the property of the generated optical signal and the dispersion penalty which is related to chirp. The simulation results show that the output phase of the optical RZ-DPSK signal has undesirable distortion and the power has considerable loss. Furthermore, the simulation of modulator with 20 dB extinction ratio is also performed for relative analysis. The poor extinction ratio will further impact the characteristic. Even the push-pull operation is utilized, there is a residual chirp resulting from FCA and nonlinear FCD effect. This kind of chirp is characterized by the dispersion penalty.