A compact electro-optical “NOR” logic gate device based on silicon-on-insulator (SOI) platform is proposed and investigated theoretically. By introducing a hook-type waveguide, the signal could be coupled between the bus and hook-type waveguide to form an optical circuit and realize NOR logic gate. We can easily realize the NOR logical function by the voltage applied on the coupling components. The numerical simulation shows that a high coupling efficiency of more than 99% is obtained at the wavelength of 1550 nm, and the footprint of our device is smaller than 90 μm2. In addition, the response time of the proposed NOR logic gate is 3 ns with a switching voltage of 1.8 V. Moreover, it is demonstrated that such NOR logic gate device could obtain an extinction ratio of 21.8 dB. Thus, it has great potential to achieve high speed response, low power consumption, and small footprint, which fulfill the demands of next-generation on-chip computer multiplex processors.
Substrate-based tuning of plasmon resonances on gold nanoparticles (NP) is a versatile method of achieving plasmon
resonances at a desired wavelength, and offers reliable nanogap sizes and large field enhancement factors. The
reproducibility and relative simplicity of these structures makes them promising candidates for frequency-optimized
sensing substrates. The underlying principle in resonance tuning of such a structure is the coupling between a metal
nanoparticle and the substrate, which leads to a resonance shift and a polarization dependent scattering response. In this
work, we experimentally investigate the optical scattering spectra of isolated 60 nm diameter gold nanoparticles on
aluminum oxide (Al2O3) coated gold films with various oxide thicknesses. Dark-field scattering images and scattering
spectra of gold particles reveal two distinct resonance modes. The experimental results are compared with numerical
simulations, revealing the magnitude and phase relationships between the effective dipoles of the gold particle and the
gold substrate. The numerical approach is described in detail, and enables the prediction of the resonance responses of a
particle-on-film structure using methods that are available in many available electromagnetics simulation packages. The
simulated scattering spectra match the experimentally observed data remarkably well, demonstrating the usefulness of
the presented approach to researchers in the field.
A Fiber-optic liquid-level sensor based on etched fiber Bragg grating (FBG) cladding mode resonance is proposed and
demonstrated both theoretically and experimentally. The theoretical model of the FBG cladding mode liquid-level sensor
is built under a three-layer step-index fiber geometry. Response of cladding mode resonance spectra to the variation of
ambient liquid level are studied and simulated numerically with couple mode theory and transmission matrix method. In
the experiments, a chemical etching method is adopted to diminish the fiber cladding diameter and increase the
sensitivity of cladding mode resonances to the ambient refractive index change. Dependences of FBG cladding mode
resonance spectra on the liquid-level variation are measured and the experiments data match the model well.
For the high absorption loss of the Electro-optic (EO) polymers, there are only a few reports on polymeric EO switches.
This paper presents a new design and fabrication method of the polymer 1×2 Mach-Zehnder Interference (MZI) switch
operating at 1550nm. The switch is consists of two vertically coupled waveguides located at different levels. And it will
be easier to fabricate by traditional technology. The finite difference Beam Propagation Method (BPM) has been used to
analyze the device propagation characteristics. The result indicated that the propagation loss of this Three-dimensional
(3-D) switch is decreased 2dB by that of the ordinary two-dimensional (2-D) switch. And this kind of structure has high
potential for the application of low-loss optical modulator and attenuator.
Optical probes are now routinely used in a remarkable number of imaging applications in the life sciences and medicine. We report the design, synthesis and characterization of a novel nanoprobe for biological applications based on surface enhanced Raman scattering (SERS). Specifically, the nanoprobe consists of magnetic Fe3O4 nanoparticles immobilized with silver nanoparticles and SERS tags. An efficient cellular uptake has been confirmed with confocal laser scanning microscopy. The nanoprobe retains its excellent SERS signals when incorporated into a cell. Besides, the probe also delivers spatially localized chemical information from its biological environments. The multi-functional probe is likely to be useful to develop new tools for targeted molecular probing of cells and provide a new way to monitor the complex changes at cellular level.
A highly sensitive liquid-level sensor based on etched fiber Bragg grating is proposed and demonstrated. The fiber Bragg
grating is etched to enhance the sensitivity to the refractive index of liquid, when a portion of etched fiber Bragg grating
is immersed in the liquid, the original single transmission dip splits into two transmission dips because of the fiber Bragg
grating spectrum is affected by the fraction of the length of the etched fiber Bragg grating that is surrounded by the liquid.
By measuring the transmission dips variations, the liquid level can be measured. The experiments show that for a liquid
level variation of 24mm, the transmission dip difference changes about 32dB. Also in the linear region, a high liquid
level sensitivity of 2.56dB/mm is achieved.