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 Fe<sub>3</sub>O<sub>4</sub> 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.
We have demonstrated efficient three-photon excitation in a number of nonlinear organic materials developed
at our center or in cooperation with other research groups. The three-photon absorption (3PA) properties of
these materials are studied using a femtosecond Ti:sapphire oscillator-amplifier laser system associated with an
optical-parametric amplifier. Considering the transverse intensity distribution of the incident beam during
measurements, the 3PA induced nonlinear transmission of the incident beam with a Gaussian transverse spatial
profile is derived. Some of the 3PA-active materials are highly fluorescent while some others are
nonfluorescent. In one of these materials, vibrational resonance enhanced broadband multiphoton absorption
was founded. These materials can be used in optical power limiting and stabilization, frequency-upconversion
imaging and microscopy etc. Some recent experiments of three-photon pumped power limiting and stabilization
are briefly presented.
In this paper, we show a kind of wavelength selective elements for optical communications using linearly chirped moire fiber gratings. According to the coupled-mode theory, the spectral characteristics of linearly chirped moire fiber gratings are studied. By choosing the grating length, the induced refractive index change, and the linear chirp coefficient, various optical transmission filters based on linearly chirped moire fiber gratings can be achieved. These filters are very useful for add/drop operations in wavelength-division-multiplexed (WDM) systems. A novel scheme of optical add-drop multiplexer (OADM) configuration based on linearly chirped moire fiber grating filter is proposed for flexible multiple wavelengths add-drop in WDM systems.