The spectrum of the temporal traces obtained from a phase-sensitive optical time-domain reflectometer is theoretically and experimentally analysed, demonstrating its dependence on the incident optical pulse shape. Numerical simulations and theoretical results are validated experimentally, showing a good matching for rectangular optical pulses. The influence of the photodetector bandwidth on the...

We are investigating the concept of utilizing a small gamma ray scintillation camera to help identify and localize malignant breast tumors after a suspicious finding in a mammogram. We are exploring two different photodetector technologies for a small prototype camera development. The first uses a position sensitive photomultiplier (PSPMT) as the photodetector, the second, an array of silicon P...

A visible light communication (VLC) system using an organic bulk heterojunction photodetector (OPD) is presented. The system has been successfully proven indoors with an audio signal. The emitter consists of three commercial high-power white LEDs connected in parallel. The receiver is based on an organic photodetector having as active layer a blend of poly(3-hexylthiophene) (P3HT) and phenyl C6...

We report on a photodetector in which colloidal quantum dots directly bridge nanometer-spaced electrodes. Unlike in conventional quantum-dot thin film photodetectors, charge mobility no longer plays a role in our quantum-dot junctions as charge extraction requires only two individual tunnel events. We find an efficient photoconductive gain mechanism with external quantum efficiencies of 38 elec...

The local evanescent array coupled (LEAC) chip-scale sensor is demonstrated for rapid detection of benzene, toluene and xylenes (BTX) in water at sub-ppm concentrations with minimal sample preparation. BTX analytes are found to concentrate into the chip’s Teflon AF upper cladding sensing region, causing an increase in refractive index, which modulates evanescent coupling into the chip’s integra...

The metal-semiconductor-metal ultraviolet (UV) photodetector was fabricated on the Mg(0.47)Zn(0.53)O layer grown by radio-frequency magnetron cosputtering. The photodetector shows the peak response at 290 nm with a cutoff wavelength at 312 nm. It exhibits a very low dark current of about 3 pA at 5 V bias, and the UV-visible rejection ratio (R = 290 nm/R = 400 nm) is more than 4 orders of magnit...

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Solar cells and photodetectors are devices that convert an optical input into current. A solar cell is an example of a photovoltaic device, i.e, a device that generates voltage when exposed to light. The photovoltaic effect was discovered by Alexander-Edmond Becquerel in 1839, in a junction formed between an electrode (platinum) and an electrolyte (silver chloride). The first photovoltaic devic...