An optical fiber sensor network for ultrasonic measurement based on wavelength division multiplexing (WDM) and time division multiplexing (TDM) technology is presented. Each of the sensor probes is an optical fiber extrinsic Fabry-Perot interferometer (EFPI) which is composed of the fiber’s end face and the aluminum thin diaphragm. The sensors are arranged in different wavelength domains formed...

Diffuse optical imaging is highly versatile and has a very broad range of applications in biology and medicine. It covers diffuse optical tomography, fluorescence diffuse optical tomography, bioluminescence, and a number of other new imaging methods. These methods of diffuse optical imaging have diversified instrument configurations but share the same core physical principle - light propagation...

Direct-detection (DD) optical fiber frequency division multiple access (FDMA) is a simple and practical alternative to optical heterodyne FDMA. Previous works on estimating the performance of DD optical FDMA networks have usually focused only on the (linear) crosstalk degradation, typically relying on simplifying approximations such as the dominance of the adjacent channel interference [1], [4]...

We investigate the saturation effect, which describes the violation of the linearity between the measured photoacoustic amplitude and the object's optical absorption coefficient in functional photoacoustic imaging when the optical absorption in the object increases. We model the optical energy deposition and photoacoustic signal generation and detection in a semi-infinite optical absorbing obje...

zno and zno: mn nanocrystals synthesized via reverse micelle method. the structural properties nanocrystals were investigated by xrd and transmission electron microscopy (tem). the xrd results indicate that the synthesized nanocrystals had a pure wurtzite (hexagonal phase) structure. the various optical properties of these nanocrystals such as optical band gap energy, refractive index, dielectr...

Investigations of complex nanostructured materials used in modern technologies require special experimental techniques able to provide information on the structure and electronic properties of materials with a spatial resolution down to the nanometer scale. We tried to address these needs through the combination of x-ray absorption spectroscopy (XAS) using synchrotron radiation microbeams with ...

A new type of optical rotation (OR) detector based on the phase retardation of the first-order diffraction beam has been constructed. The proposed detector responded to only OR properties by eliminating the circular dichroism (CD) effect. Thus, it could measure the optical rotatory dispersion curves in the Cotton band. Although the optical system requires the incident beam in which the phase re...

Time of flight laser range finding, scanning video imaging and deep space communications are three applications requiring very low noise optical receivers in order to achieve detection of fast and weak optical signal. Avalanche photodiode is the detector of choice for its high quantum efficiency, compact size and reduced electronics complexity. Optimal operating condition in terms of gain and t...

A theory for the signal-to-noise ratio (SNR) of optical direct-detection receivers employing return-to-zero (RZ) coding (and possibly optical preamplification) is developed. The results are valid for both signal-independent noise limited and signaldependent noise limited receivers, as well as for arbitrary optical pulse shapes and receive filter characteristics. Even if the same receiver bandwi...