Multiband Detector Research Articles

Bayesian Implications for the Primordial Black Holes from NANOGrav’s Pulsar-Timing Data Using the Scalar-Induced Gravitational Waves

Assuming that the common-spectrum process in the NANOGrav 12.5-year dataset has an origin of scalar-induced gravitational waves, we study the enhancement of primordial curvature perturbations and the mass function of primordial black holes, by performing the Bayesian parameter inference for the first time. We obtain lower limits on the spectral amplitude, i.e., A≳10−2 at 95% confidence level, when assuming the power spectrum of primordial curvature perturbations to follow a log-normal distribution function with width σ. In the case of σ→0, we find that the primordial black holes with 2×10−4−10−2 solar mass are allowed to compose at least a fraction 10−6 of dark matter. Such a mass range is shifted to more massive regimes for larger values of σ, e.g., to a regime of 4×10−3−0.2 solar mass in the case of σ=1. We expect the planned gravitational-wave experiments to have their best sensitivity to A in the range of 10−4 to 10−7, depending on the experimental setups. With this level of sensitivity, we can search for primordial black holes throughout the entire parameter space, especially in the mass range of 10−16 to 10−11 solar masses, where they could account for all dark matter. In addition, the importance of multi-band detector networks is emphasized to accomplish our theoretical expectation.

Tunable Multiband Halide Perovskite Tandem Photodetectors with Switchable Response.

Photodetectors with multiple spectral response bands have shown promise to improve imaging and communications through the switchable detection of different photon energies. However, demonstrations to date have been limited to only two bands and lack capability for fast switching in situ. Here, we exploit the band gap tunability and capability of all-perovskite tandem solar cells to demonstrate a new device concept realizing four spectral bands of response from a single multijunction device, with fast, optically controlled switching between the bands. The response to monochromatic light is highly selective and narrowband without the need for additional filters and switches to broader response bands on applying bias light. Sensitive photodetection above 6 × 1011 Jones is demonstrated in all modes, with rapid switching response times of <250 ns. We demonstrate proof of principle on how the manipulation of the modular multiband detector response through light conditions enables diverse applications in optical communications with secure encryption.

Novel CMOS-based multi-band terahertz detector for passive imaging

The existing terahertz detectors based on complementary metal oxide semiconductor cannot meet the design requirements of passive terahertz focal plane imaging chips owing to the problems of excessive noise or high-power consumption. To overcome this limitation, this study innovatively proposes using the gate of an N-type metal oxide semiconductor (NMOS) as a matching impedance of a multi-band terahertz on-chip antenna. In this way, the conversion of incident radiation into heat is achieved, and it is concentrated above the NMOS channel. The temperature characteristics of the equivalent impedance of the NMOS in the cutoff region are used to measure the incident radiated power without the DC bias current. The principle and simulation results of the proposed detector are given by system modeling, multi-band terahertz on-chip antenna design, and detector design. The experimental results show that the noise equivalent power of the proposed detector is very close to 1 under liquid nitrogen cooling, which can meet the design requirements of passive terahertz focal plane imaging chips.

Multiband gravitational-wave parameter estimation: A study of future detectors

The first detection of a gravitational-wave signal of a coalescence of two black holes marked the beginning of the era of gravitational-wave astronomy, which opens exciting new possibilities in the fields of astronomy, astrophysics and cosmology. The currently operating detectors of the LIGO and Virgo collaborations are sensitive at relatively high frequencies, from 10 Hz up to about a kHz, and are able to detect gravitational waves emitted in a short time frame of less than a second (binary black holes) to minutes (binary neutron stars). Future missions like LISA will be sensitive in lower frequency ranges, which will make it possible to detect gravitational waves emitted long before these binaries merge. In this article, we investigate the possibilities for parameter estimation using the Fisher-matrix formalism with combined information from present and future detectors in different frequency bands. The detectors we consider are the LIGO/Virgo detectors, the Einstein Telescope (ET), the Laser Interferometer Space Antenna (LISA), and the first stage of the Deci- Hertz Interferometer Gravitational wave Observatory (B-DECIGO). The underlying models are constructed in time domain, which allows us to accurately model long-duration signal observations with multiband (or broadband) detector networks on parameter estimation. We assess the benefit of combining information from ground-based and space-borne detectors, and how choices of the orbit of B-DECIGO influence parameter estimates.

Monolithic resonant CMOS fully integrated triple-band THz thermal detector.

Multiband terahertz (THz) detectors have attractive prospects in the areas of THz sensing and imaging. This paper presents a monolithic resonant CMOS fully integrated triple-band THz thermal detector that is composed of a compact loop antenna and an optimized proportional to absolute temperature (PTAT) sensor, leading to an uncooled, compact, low-cost, easy-integration, and mass-production multiband detector. The principles of operation, theoretical calculation, and experimental validation are demonstrated in detail. Calculated responsivities are 34.9 V/W, 51.6 V/W, and 47.6 V/W at the operation frequencies of 0.91 THz, 2.58 THz, and 4.3 THz, respectively, for the natural atmospheric windows. Relatively better experimental results are obtained at 0.91 THz and 2.58 THz due to the scarcity of THz sources, showing maximum responsivities of 29.2 V/W and 46.5 V/W with minimum NEPs of 1.57 µW/Hz0.5 and 1.26 µW/Hz0.5, respectively. The presented triple-band thermal detector has the natural scalability to focal plane arrays, providing great potential for multiband THz sensing and imaging systems.

第二代静止轨道气象卫星用多波段红外探测器封装及性能

第二代静止轨道气象卫星用多波段红外探测器封装及性能

Invariant Target Detection in Multiband FM-Based Passive Bistatic Radar

FM-based passive bistatic radars (PBRs) exploiting a single broadcasted channel suffer from time-varying detection performance due to the time-varying program content of the transmitted signal as well as the propagation condition of that channel. To circumvent this matter, it is a viable idea to exploit multiple broadcasted channels from a single transmitter for detection. In this case, we formulate the problem of detecting a target in the presence of interference signals such as receiver noise, direct signal, multipath/clutter echoes and interfering targets as a composite hypothesis test. To address this, we derive a multiband uniformly most powerful invariant (UMPI) test as an optimal invariant detector. Closed-form expressions for calculating false alarm probability and detection probability for the target models of Swerling 0 and Swerling 1 are derived. A thorough performance assessment is also given, and the results show the robustness of the proposed multiband detector against the time-varying program content of FM radio channels. In addition to the reliable detection performance, a multiband PBR system offers advantages in terms of combined diversity gain and frequency diversity gain as compared with a single band PBR system. The former happens due to the joint exploitation of multiple broadcasted channels for detection, while the latter occurs when independent returns are received from one target over different frequency channels.

Design of resonant-cavity-enhanced multi-band photodetectors

A theoretical analysis to improve the quantum efficiency of detectors sensing in multiple spectral bands is presented. The effective coupling between the incoming light and multiple absorbing regions for simultaneously improving the multi-band absorption efficiency is obtained by using resonant-cavity structures. An optimized cavity with only a Au bottom reflector gives rise to an enhancement factor of 11 in absorption compared to the conventional detector without the cavity. Further improvement, by a factor of 26, can be attained with the aid of a dual-band Bragg reflector placed at the top. The resulting multi-band resonant-cavity detector increases the response in three out of four detection bands contributing to the spectral range from visible to long-wave infrared (IR). The optimized detector is capable of serving multiple purposes, such as regular IR detection for atmospheric windows, gas sensing, and for optical communications.

A super-pixel QWIP focal plane array for imaging multiple waveband temperature sensor

The multi-waveband temperature sensor (MWTS) array, in which each super-pixel (2 × 2 pixel cell) operates at four distinct thermal infrared (IR) wavebands is being developed. Using this high spatial resolution, four-band thermal IR band detector array, accurate temperature measurements on the surface of an object can be made without prior knowledge of its exact emissivity. This multi-band detector involves intersubband transition in III–V semiconductor-based quantum layered structures. Each detector stack absorbs photons within the specified wavelength band while allowing the transmission of photons in other spectral bands, thus efficiently permitting multi-band detection. This produces multiple, spectrally resolved images of the scene that are recorded simultaneously in a single snapshot on the FPA. From the multispectral images and calibration information about the system, computational algorithms are used to evaluate the temperature on the surface of a target.

Monolithically integrated near-infrared and mid-infrared detector array for spectral imaging

A multi-band focal plane array sensitive in near-infrared (near-IR) and mid-wavelength infrared (MWIR) is been developed by monolithically integrating a near-infrared (1–1.5μm) p–i–n photodiode with a mid-infrared (3–5μm) QWIP. This multiband detector involves both intersubband and interband transitions in III–V semiconductor layer structures. Each detector stack absorbs photons within the specified wavelength band, while allowing the transmission of photons in other spectral bands, thus efficiently permitting multiband detection. Monolithically grown material characterization data and individual detector test results ensure the high quality of material suitable for near-infrared/QWIP dual-band focal plane array.

Multi-band and broad-band infrared detectors based on III–V materials for spectral imaging instruments

Quantum well infrared photodetector technology has shown remarkable success by realizing large-format focal plane arrays in both broad-bands and in multi-bands. The spectral response of these detectors based on the III–V material system are tailorable within the mid and long wavelength IR bands (∼3–25 μm) and possibly beyond. Multi-band and broad-band detector arrays have been developed by vertically integrating stacks of multi quantum wells tailored for response in different wavelengths bands. Each detector stack absorbs photons within the specified wavelength band while allowing the transmission other photons, thus efficiently permitting multiband detection. Flexibility in many design parameters of these detectors allows for tuning and tailoring the spectral shape according to application requirements, specifically for spectral imaging instruments.

Multi-band Terahertz Imaging System Design

AbstractDeveloping visualization devices in far infrared reveals tremendous advantages and focused the research of space agencies, defense and security as well many other private companies oriented to science. The THz wave emitters and receivers are less developed, compared to its neighboring bands (microwave and optical). During the past decade, THz waves have been used to characterize the composition and properties of solid, liquid and gas phase materials to identify their molecular structures. At the base of this development stays the possibility of achieving microstructures from conductive or super-conductive materials able to select by resonant criteria the emerging photons and drive into specialized detection devices. The problem to be solved is the ratio S/N because the energy of a single 1THz photon is 4.1 meV equivalent to a 47K temperature.A group of such highly selective micro-antenna can be grouped into a unit cell - called elementary multi-band detector. The development of resonant structures for frequency selectivity and directivity reasons coupled with the electrical field amplification and detection in low noise quantum transistors. Such an electronic system might be integrated in a modular structure and by multiplicity to create spatial sensors and phased arrays.

On adaptive multiband signal detection with GLR algorithm

An adaptive multiband detector based on the principle of the generalized likelihood ratio test (GLR) is presented. Its detection performance is studied and compared with that of the corresponding single-band GLR detector. The multiband detector is shown to significantly outperform the single-band under the chosen system constraint, especially when the amount of data available from a single frequency band is severely limited by the environment. >

Detection of 1-of-M orthogonal signals: asymptotic equivalence of likelihood ratio and multiband models

A closed-form solution for the optimal detection of 1-of-M orthogonal signals is presented for low signal energy. The solution is obtained for the Poisson case and applies as well in the Gaussian equal-variance case. Detectability, d', is given by S/(MB)((1/2)), where S is the signal energy (in photons) and B is the background. This result is obtained by demonstrating that the decision rule of the likelihood ratio (optimal) detector is identical to that of the multiband detector, which sums photon counts for all M signal loci.