InGaAs/AlGaAs multiple quantum wells used for 4.3 μm mid-wavelength infrared quantum well infrared detectors were grown by molecular beam epitaxy. In composition loss was observed and quantitatively studied by high-resolution X-ray diffraction technology. By this In composition loss effect, the energy band engineering on the photo-response wavelength is not easily achieved. A thin AlGaAs barrie...

In this paper we describe a free-space optics (FSO) based mobile sensor network that is not subject to RF interference common to wireless sensor networks. FSO-based mobile sensor networks can potentially be used in applications where security of communication, including freedom from susceptibility to jamming, is important. The design of nodes containing multiple transceivers each composed of an...

In the beginning of this century, a new type of detector, superconducting nanowire single photon detector (SNSPD or SSPD) joined the family of superconducting sensors and detectors. Soon, it has been turning to be one of the most important players in this family since it surpasses the semiconducting single photon detectors (APD: avalanche photodiode and PMT: photo multiplier tube) with many adv...

A photonic instantaneous frequency measurement system capable of measuring both RF frequency and power simultaneously, is conceived and practically demonstrated. This system employs an RF photonic Hilbert transformer together with low-cost, low-frequency photo-detectors to obtain two orthogonal DC measurements. This system exhibits a frequency range of 1-10 GHz. Wider frequency range can be ach...

Minimum achievable temperature of ~110 K is measured in a 5% doped Yb:YLF crystal at λ = 1020 nm, corresponding to E4-E5 resonance of Stark manifold. This measurement is in excellent agreement with the laser cooling model and was made possible by employing a novel and sensitive implementation of differential luminescence thermometry using balanced photo-detectors.

When photon-counting detectors are calibrated in the presence of a background signal, deadtime effects can be significant and must be carefully accounted for to achieve high accuracy. We present a method for separating the correlated signal from the background signal that appropriately handles deadtime effects. This method includes consideration of pulse timing and afterpulsing issues that aris...

The forward proton spectrometer is part of the H1 detector at the HERA collider. Protons with energies above 500 GeV and polar angles below 1 mrad can be detected by this spectrometer. The main detector components are scintillating fiber detectors read out by position-sensitive photo-multipliers. These detectors are housed in so-called Roman Pots which allow them to be moved close to the circul...

Terahertz (THz) radiation, often referred to the frequency range from 0.1 to 10 THz, is the focus of an active and fast growing research community. However, this frequency range located in the electromagnetic spectrum between the microwave band and infrared band, was known as the “THz-gap” until the late 1980's. A lack of available coherent sources and detectors rendered this frequency range in...

In this paper, a closed-form symbol error rate (SER) for space-time block code (STBC) in free space optic (FSO) systems is derived. Then the asymptotic performance analysis presents the insight values, the diversity order and the SNR gain. We show that the SNR gain worsens as the number of lasers and photo detectors increases.

Single crystal of Thallium doped cesium Iodide –Scintillator crystal was grown using vertical Bridgeman technique. The grown crystal was included for cutting and polishing for the characterization purpose and this crystal was studied by optical transmission properties, photo luminescence and thermally luminescence characteristics. Gamma-ray detectors were fabricated using the grown crystal that...