Much progress has been made over the past several years in the development of high-speed photodiode detectors. A detection bandwidth of 105 GHz together with a responsivity of 0.1 A# have been reported for a metalsemiconductor-metal (MSM) photodiode.’ The most common approach to increasing the bandwidth in MSM photodiodes (at least up to 100 GHz) is to shorten the carrier transit time by reduci...

An automated, qualitative screening HPLC method for the identification of basic compounds in urine has been established. A 1-ml volume of urine was extracted by on-line extraction and separated on two coupled strong cation-exchange columns under isocratic conditions. The use of the photodiode-array detector (DAD, = 190370 nm) gave access to a library of > 2600 toxicologically relevant compounds...

We propose a design for a photon-counting detector that is capable of resolving multiphoton events. The basic element of the setup is a fiber loop, which traps the input field with the help of a fast electro-optic switch. A single weakly coupled avalanche photodiode is used to detect small portions of the signal field extracted from the loop. We analyze the response of the loop detector to an a...

This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The max...

We present a new type of compressive spectroscopy technique employing a liquid crystal (LC) phase retarder. A tunable LC cell is used in a manner compliant with the compressive sensing (CS) framework to significantly reduce the spectral scanning effort. The presented optical spectrometer consists of a single LC phase retarder combined with a single photo detector, where the LC phase retarder is...

Flavonoids are important polyphenolic secondary metabolites in plant. Citrus reticulata 'Chachi' fruit are rich in flavonoids and are being used as functional antioxidant ingredients for the treatment of atherosclerosis and cancer, etc. A high performance liquid chromatography-photodiode array detection system was used to analyze five flavonoids, namely, naringin, hesperidin, didymin, tangereti...

A newly fabricated Mcaolithic InGaAs Active Pixel Image Sensor’z is presented, and its readout characteristics are described. The sensor is fabricated fhrn InCfiAs epitaxirdly deposited on an InP substrate. It consists of an InGaAs photodiode connected to InP depletion-mode Junction field effect transistors (J-s) for signal buffering, selection and reset. The monolithic sensor eliminates the ne...

Current techniques used to image gene expression in vivo use invasive surgical procedures or harmful gamma rays to analyze tissue. Optical imaging of tissue is difficult because the majority of light is absorbed by tissue. In the near infrared (NIR) region, however, absorption of light decreases and it is possible to “see” through tissue. Though absorption is minimal in the near infrared region...

We describe how the National Institute of Standards and Technology obtains a scale of absolute spectral response from 406 nm to 920 nm. This scale of absolute spectral response is based solely on detector measurements traceable to the NIST High Accuracy Cryogenic Radiometer (HACR). Silicon photodiode light-trapping detectors are used to transfer optical power measurements from the HACR to a mon...

The absolute flux of a femtosecond vacuum-ultraviolet (VUV) photon source based on the high-order harmonic generation of a femtosecond Ti:sapphire laser and monochromatized with a grating monochromator is determined both on a shot-to-shot basis and averaged over seconds by a calibrated gas monitor detector. The average flux is compared with the average flux as determined with a calibrated GaAsP...