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Fundamental performance limitations of infrared detectors
Published in Antoni Rogalski, Infrared and Terahertz Detectors, 2019
The minimum detectable signal power—or noise equivalent power (NEP)—is defined as the rms signal power incident upon the detector required to equal the rms thermal noise power. Hence, if the temperature fluctuation associated with GR is the only source of noise, εNEP=ΔPth=(16AεσkT5)1/2,
Fundamental Detector Performance Limits
Published in Antoni Rogalski, 2D Materials for Infrared and Terahertz Detectors, 2020
The minimum detectable signal power – or noise equivalent power (NEP) – is defined as the rms signal power incident upon the detector required to equal the rms thermal noise power. Hence, if the temperature fluctuation associated with GR is the only source of noise: εΝΕΡ=ΔPth=(16AεσkT5)1/2
Photodetector Fundamentals
Published in Joachim Piprek, Handbook of Optoelectronic Device Modeling and Simulation, 2017
The term noise refers to unwanted electrical signal that masks the signal to be detected. Several noise sources, such as thermal, shot, dark current, and flicker noise, are present in PDs and associated circuits and make it difficult to detect weak signals. The minimum detectable signal corresponds to an rms output signal equal to that generated by noise. The signal-to-noise ratio (SNR) is then unity. The noise equivalent power (NEP), a measure of the minimum detectable signal, is defined as the power of sinusoidally modulated monochromatic optical signal that generates the same rms output power in the ideal noise-free detector as the noise signal produced in a real detector.
Novel operating band design schemes for high-contrast passive terahertz security screening systems
Published in Journal of Modern Optics, 2021
Zhang Yongfeng, Zhang Shufang, Sun Xiaoling
Progress has also been made in the development of passive terahertz security screening systems. Table 1 depicts several passive terahertz security screening systems and their main system parameters [9–18]. It has been shown that the noise equivalent power (NEP) or noise equivalent temperature difference (NETD) of the low-temperature system [9–14] is significantly better than that of the room temperature system [15–18]. Current research focuses on reducing the noise of room temperature systems, thereby reducing costs by eliminating applicable cooling equipment. Fast-response developments mainly aim at meeting the needs of real-time imaging processing. The frame rates reported in [10, 11, 15, 17] have all reached more than 10 Hz. High-resolution systems are equipped with 1-K or larger pixel arrays. Terahertz imaging arrays based on integrated circuit technology are becoming a hot topic as they allow for single-chip integration of sensors and readout circuits.
Terahertz thermometry system to measure temperature in the thickness of a solid polymer*
Published in Quantitative InfraRed Thermography Journal, 2018
Cyndie Poulin, Meriam Triki, Karim Bousmaki, Alexandre Duhant, Hervé Louche, Bertrand Wattrisse
The set up was based on a mW compact source (Radiometer Physics GmbH) which emits at 165.78 GHz, corresponding to a 1.80 mm wavelength in air. The source frequency was generated through a radio frequency synthesiser (Rohde-Schwarz SMB 100A) with a ± 64 MHz frequency excursion. All used lenses are planoconvex and their focal length about 100 mm. The beam was first collimated through a L1 lens and then focused on the sample through a L2 lens. The beam was then collimated again through a L3 lens and finally focused on the detector through a L4 lens. The beam diameter focused on a sample was about 7.3 mm. The setup was designed to allow the removal of the THz detection unit in order to measure the surface temperature with an infrared camera. The T-Waves Technologies detector is based on a nano-transistor sensor whose responsivity is about 40 kV/W at 0.3 THz, NEP (noise equivalent power) of 50 pW/Hz (as formulated in [13]).
Autonomous underwater vehicles - challenging developments and technological maturity towards strategic swarm robotics systems
Published in Marine Georesources & Geotechnology, 2019
N. Vedachalam, R. Ramesh, V. Bala Naga Jyothi, V. Doss Prakash, G. A. Ramadass
Where ‘PT’ is the transmitted optical power in W, ‘θ’ is the divergence angle of the transmitted beam in degrees, ‘z’ is the optical link distance/range in meters, noise equivalent power (NEP) is the noise equivalent power for the operating bandwidth, ‘c’ is the attenuation coefficient of the underwater channel in m−1, ‘D’ is the receiver aperture area in m2, ‘’ is the beam angle from the line of sight in degrees, BW is the band width in MHz and BR is the bit rate in bits/sec.