Sean Mathai

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Three porphyrin systems have been characterised for use in two-photon fluorescence imaging of biological samples. We have determined the two-photon absorption cross sections (sigma(2)) of the di-cation, free-base and metallated forms of hematoporphyrin derivative (HpD), hematoporphyrin IX (Hp9) and a boronated protoporphyrin (BOPP) using the open-aperture(More)
The singlet oxygen formation quantum yield (Phi(Delta)) for solutions of the di-cation, free-base and metallated forms of hematoporphyrin derivative (HpD), hematoporphyrin IX (Hp9) and a boronated protoporphyrin (BOPP) are reported using the method of direct detection of the characteristic phosphorescence following polychromatic excitation. Values of(More)
Loboi Swamp is a 1AE5 km 2 freshwater wetland situated near the equator in the Kenya Rift Valley. The climate is semi-arid: precipitation is 700 mm year)1 , and evapotranspiration is 2500 mm year)1. Some of the wetland water is currently used for irrigation. An interdisciplinary study was conducted on the geology, hydrology, pedology and biology of the(More)
We present an electrothermally actuate scanner for board-to-board free-space optic systems capable of zero standby power. U-actuators, brakes, and lens frames are design and characterized with a vertical cavity su laser (VCSELs) for dynamic beam s demonstrate up to 170 µm displacement, speed of 350 µm/s. The mechanical brakes force of 1.6 mN with switching(More)
Balanced photodetectors are of great interest to analog fiber optic links because they can suppress laser relative intensity noise (RM) and amplified spontaneous emission noise (ASE) from erbium-doped fiber amplifiers (EDFA) [ 11. Because balanced photodetectors can achieve shot noise-limited link performance, the noise figure and spurious-free dynamic(More)
High power, high frequency photodetectors play a key role in determining the performance of analog and microwave fiber optic links. The high power photodetectors allows the use of high power laser sources in externally modulated links. This can significantly reduce the RF insertion loss, and increase the spurious free dynamic range and signal-to-noise ratio(More)
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