A broadband terahertz (THz) quasi-optical detector based on 3D-printed lens packaging has been pre & hybull; sented, covering two typical atmospheric windows at 220 GHz and 340 GHz. The detector consists of an antenna-coupled detector chip and a 3D-printed lens. The chip was packaged on a multi-layer dielectric laminate, with a Schottky diode directly integrated across the feeding terminals of the on-chip antenna. The on-chip integrated broadband planar bowtie antenna was printed on a quartz substrate within the operation frequency range of 201-360 GHz, functioning as a radiator and a radio frequency (RF) choke. Bandwidth enhancement is achieved using a pair of capacitively loaded loops (CLLs) without increasing the antenna size. High-impedance folded low-fre & hybull; quency (LF) leads are incorporated to suppress high-frequency signal leakage. A lightweight, low-cost 3D-print & hybull; ed lens combined with an embedded metallized reflector enables unidirectional radiation and improved mechanical robustness. The detector achieves a maximum voltage responsivity of 2200 V/W over 200-230 GHz and 1885 V/ W over 320-350 GHz. Measured radiation patterns agree well with simulations.
The fundamental concepts, operating principles, and recent advancements in integrated sensing and commu- nication (ISAC) are presented. A comprehensive review of multiband and large-frequency-ratio microwave/millimeterwave transmission lines, antennas, and passive components-primarily filters and couplers-that are currently suitable for ISAC application scenarios is provided. Various implementation strategies and fabrication techniques for these multi- band and high-frequency-ratio structures are comparatively analyzed. The technical characteristics, RF performance, and respective advantages and limitations of different design approaches are systematically summarized. This review of- fers a diverse and in-depth reference for the continued development of high-performance microwave/millimeter-wave front-end components tailored for ISAC applications.
Silicon-based phototransistor detectors, offering advantages such as high internal gain, cost-effective and compatibility with CMOS technology, are becoming one of the key devices for large-scale photon integration chip and have significant potential for applications in short-distance optical interconnecting. To relieve its inherent optimization contradiction between responsivity and bandwidth performance, a novel couple ridge waveguide SiGe/Si phototransistor was proposed, in which the carrier transport and the photon propagation were perpendicu & hybull; lar and demonstrate the independent optimization on absorption efficiency and operating speed. The optical propa & hybull; gation mode in the SiGe/Si ridge waveguide were analyzed between the single mode and the multiple mode. The geometric parameters of the ridge waveguide to achieve high absorption efficiency were optimized. The ridge waveguide SiGe/Si phototransistor were fabricated using technology compatible with CMOS process platform and achieved a responsivity of 6. 4 A/W with the dark current of 10 nA.
To achieve the detection of extremely weak signals from pyroelectric infrared detectors and to meet the demands of high-sensitivity applications, this paper proposes a dual-capacitor transimpedance amplifier (CTIA) readout structure featuring a variable array size. Additionally, a bandgap reference and a low dropout regulator (LDO) are designed as the bias circuit to provide voltage bias, in order to meet the requirements of low noise, low power consumption, large dynamic range and portability. The circuit is designed in TSMC 0. 18 mu m 1P6M CMOS process under a 3. 3V supply. For the layout implementation, advanced techniques, including dummy structures and guard rings, are employed to improve device matching, overall layout symmetry, as well as the noise immunity and electrical stability of the analog circuitry.
An improved multi-feature fusion scheme is proposed to address the edge signal loss problem inherent in existing clutter filtering methods for Ka-band millimeter-wave cloud radar. A recognition model is first constructed based on the temporal and vertical continuity of the reflectivity factor of echo signals to perform preliminary clutter identification. Subsequently, morphological binary dilation operations are introduced to generate candidate regions along cloud and fog edges, and neighborhood analysis techniques are employed to achieve precise determination of signal boundaries. The proposed algorithm is validated against co-located lidar observations. Results demonstrate that the scheme effectively suppresses clutter while preserving cloud and fog edge signals with substantially improved completeness, thereby resolving the edge signal loss problem associated with existing clutter filtering approaches and enhancing the overall data quality of millimeter-wave cloud radar.
Infrared focal plane digital readout circuit is one of the important development directions of infrared focal plane detection technology. Aiming at the requirements of high-speed, high-precision and multi-application scenarios of infrared focal plane, a new architecture of multi-mode incremental Sigma-Delta analog-to-digital converter (ADC) with 3-bit quantizer is designed. By integrating the data weighted average algorithm into the 3-bit quantizer, the influence of capacitor mismatch in the feedback loop is reduced, and the conversion speed and accuracy of ADC are improved; the multiplexer was embedded in the CIC digital extraction filter to realize ADC supporting different conversion speeds and output bits. Based on 180 nm CMOS process design, the design of multi-mode incremental Sigma-Delta ADC is com- pleted. The simulation results show that the conversion between conversion speed and output bits can be realized under multi-mode operation, and the ADC conversion speed increases from 12. 5 ksps to 100 ksps, and the output bits in- crease from 15 bits to 24 bits; at a conversion speed of 50 ksps, the effective number of bits of the post-simulation ADC reaches 13. 1 bits, and the current consumption of each column ofADC is only 90 mu A.
In high-electron-mobility transistor (HEMT) terahertz detectors, an excessively wide gate can generate oblique modes in the channel, resulting in weakened resonant detection signals and a broadened resonance peak. To address this issue, a side-gate HEMT (EdgeFET) structure was proposed. A resonant detection model for the side-gate device was established based on the hydrodynamic equations of the two-dimensional electron gas (2DEG) in conventional HEMT. A side-gate HEMT detector was fabricated, and terahertz resonant detection ex & hybull; periments were conducted at 77 K. The experimental results indicated that EdgeFET demonstrated distinct reso & hybull; nant responses at 77 K, with the resonant responsivity reaching 3. 7 times the maximum non-resonant responsivi & hybull; ty. The experimental data were fitted using the theoretical model to validate its accuracy. These results strongly confirm the effectiveness of EdgeFET in enhancing the resonant performance of the detector, providing a new technological approach for the development of next-generation high-performance terahertz detectors.
To address the requirements for ultra-low noise and zero-bias operation in MoS2-BP-MoS2 van der Waals pho- tovoltaic detectors, a readout circuit was designed based on a capacitive transimpedance amplifier (CTIA) incorporating chopper stabilization (CS) and correlated double sampling (CDS) techniques. The design employed a multi-node chop- per architecture operating at 40 kHz to suppress 1/f noise, while CDS was utilized to eliminate KTC noise and ripple. A unity-gain buffer provided dynamic bias control, achieving a bias error below 200 mu V. Experimental results demonstrat- ed an equivalent input noise current of 119. 35 fA, a total integrated noise reduction of 32. 83%, and a power consumption of 990 mu W in a 0. 35 mu m CMOS process. This work presents a high-precision, low-noise readout solution for twodimensional material photodetectors.
Understanding the distribution characteristics of atmospheric components and parameters at different altitudes plays a crucial role in deeply comprehending climate change and addressing climate issues. To meet the detection requirements for vertical profiles of multiple atmospheric components (H2O,CO2,CH4,N2O,O-3,CO, etc. ) and line-of-sight wind speed, this study designs an LEO-LEO infrared laser occultation (LIO) system. For payload design, the laser transmitter employs broadband frequency-locked laser source technology to generate highly stable infrared lasers. The receiver utilizes multi-grating spatial heterodyne spectroscopy (SHS), achieving wide spectral coverage (2-2. 5 mu m) and high spectral resolution (<= 0. 15 cm(-1)). For data application and orbit simulation, an Abel transform-based inversion method is proposed to synchronously retrieve atmospheric composition and parameter profiles in the Upper Troposphere and Lower Stratosphere (UTLS). Additionally, a simulated occultation orbit system demonstrates a daily occultation event frequency of up to 61 times, with optimized data acquisition processes for single events.
The demand for high-sensitivity short-wave infrared (SWIR) detection technology is urgent in frontier fields such as lidar and quantum communication. Heterojunction phototransistor (HPT), benefiting from its internal gain mechanism, provides an effective solution for breaking the physical limit of conventional PIN photodetector in sensitivity. This paper focuses on the base-size effect of InP/GaAsSb/InGaAs HPTs with type-II barrier structure. Devices with two different base structures were fabricated by controlling the etching process. Measurement results show that maintaining an intact base structure significantly improves device performance: at a bias voltage of-2 V, the responsivity and internal current gain reach 141 A/W and 160, respectively-superior to those of devices with etched bases. Temperature-dependent analysis and size-effect studies further reveal that the dark current of the intact-base device is dominated by diffusion mechanisms and exhibits better dimensional stability, whereas the etched-base device suffers from pronounced generation-recombination current and surface leakage current caused by sidewall defects. Under low-temperature and weak-light conditions, carrier trapping by these defects leads to severe degradation of photo response. This study clarifies the critical influence of base structural design on HPT performance and provides valuable theoretical and experimental guidance for optimizing high-performance SWIR detectors.
Surface-microstructured silicon exhibits unique optical properties, demonstrating promising potential for applications in photoelectric sensors, solar cells, and related fields. To further explore the optoelectronic modulation effects based on its surface architecture, this study presents a novel heterojunction photodetector constructed by integrat- ing MXenes (Ti3C2Tx) with microstructured silicon substrate through spin-coating and other fabrication techniques. Comparative studies were conducted on commercial silicon, microstructured silicon, and Ti3C2Tx/microstructured silicon devices under varying wavelengths and optical power densities. The current-voltage (I-V) characteristics and photoresponse performance reveal that the Ti3C2Tx/microstructured silicon photodetector exhibits significantly superior external quantum efficiency (EQE) and responsivity across a broad spectral range of 200-1750 nm compared to commercial silicon and microstructured silicon detectors. Notably, in the near-infrared region (1100-1800 nm), the device demonstrates exceptional performance, achieving EQE exceeding 1000% and responsivity greater than 10 A/W. In contrast, commercial silicon photodetector in the same spectral range shows EQE below 10% and responsivity no higher than 0. 3 A/W, while microstructured silicon photodetector exhibits EQE of below 15% and responsivity limited to 0. 08 A/W. Further dynamic response and bias-dependent analyses indicate that the Ti3C2Tx coating, owing to its high conductivity and the built-in electric field formed at the heterojunction with microstructured silicon, significantly enhances detection capability from the NIR to MIR. Additionally, the response time is remarkably reduced from 38 ns to 20 ns. This heterojunction holds great promise for high-speed photodetection in optical communications, LIDAR, photoelectric sensing, and other advanced optoelectronic applications.
Terahertz (THz) detectors, which play a pivotal role in photoelectric conversion, are essential compo & hybull; nents in modern information society. Through chemical vapor deposition (CVD), large-area PtTe2 thin films were synthesized, allowing for the fabrication of THz detectors with varying channel lengths. Characterization re & hybull; sults demonstrate that the device response is linearly dependent on both bias voltage and incident power, while the responsivity is inversely proportional to channel length and operational frequency. These findings align with theo & hybull; retical calculations based on the electromagnetic induced well (EIW) mechanism. Notably, EIW-based devices exhibit a rapid response time of approximately 7. 6 mu s, with a noise equivalent power (NEP) below 7. 9 & times;10-15 W/ Hz0. 5 and a specific detectivity (D*) exceeding 9 & times;1010 cm & centerdot;Hz0.5/W under limited bias conditions. These perfor & hybull; mance metrics surpass those of previously reported semimetallic PtTe2-based detectors.
A broadband terahertz (THz) detector chip supporting both direct detection and heterodyne detection modes is designed and fabricated using a 180 nm CMOS process. The detector consists of a loop antenna, a differential detection circuit based on NMOS transistors, and an impedance matching network, with a chip area of 200 & times;200 pmt. Based on the bidirectional radiation characteristic of the loop antenna, a layout scheme that places the radio frequency (RF) signal and local oscillator (LO) signal on opposite sides of the detector is proposed. This scheme eliminates the need for a beam splitter for signal coupling, thereby avoiding signal attenuation. The LO signal is generated by an external independent THz source, which offers advantages in frequency stability and output power compared with on-chip integrated LO sources. To suppress the surface wave loss of the silicon substrate, a high-resistivity silicon lens with a diameter of 12 mm and a thickness of 8 mm is integrated on the backside of the chip. The measured results demonstrate that the detector operates over a broadband frequency range of 75-325 GHz. The noise equivalent power (NEP) under heterodyne detection is more than three orders of magnitude better than that under direct detection. The detector achieves its optimal performance at 220 GHz, with a heterodyne NEP of 6. 26 fW/Hz and a direct detection NEP of 18. 42 pW/Hz(1/2).
Due to the influence of materials and processes, infrared images generally suffer from the problem of blind pixels. For infrared images from new Blocked Impurity Band (BIB) detectors, there are still issues such as limited dynamic range and significant non-uniformity. Conventional blind pixel detection and compensation methods are not fully applicable to BIB detector images. To address this issue, this paper enumerates the pros and cons of common methods for detecting and compensating blind pixels in infrared images and conducts experimental processing on actual measured BIB images one by one. However, the results indicate that the distribution of blind pixels is highly non-uniform, with a relatively high proportion of clustered blind pixels. Therefore, this paper proposes an improved blind pixel detection method and a blind pixel compensation method, and implements the algorithms using an FPGA-based hardware system platform. The analysis shows that the uniformity of blind pixel distribution and the proportion of clustered blind pixels have been optimized after the improvement, leading to a tangible enhancement in their economic viability for application.
Blocked Impurity Band (BIB) detectors have significant application potential in fields such as infrared astronomical space observation. However, studies on their temperature-dependent mechanisms remain limited. In this work, a planar p-i-n structured BIB infrared detector based on high-purity germanium was fabricated using a near-surface processing technique. The device exhibited excellent electrical and photoresponse performance under cryogenic conditions. At 3. 3K, the reverse bias current was as low as 15 pA, and good response was maintained below 15K. The blackbody detectivity reached up to 3.5 & times; 10(12)cm & centerdot;Hz(1/2)& centerdot;W-1, but decreased with increasing temperature. A current model incorporating photoexcitation, thermal excitation, and impact ionization processes was employed to simulate the experimental results. The analysis revealed that the primary mechanism for performance degradation at elevated temperatures is the significant shrinkage of the depletion region, which reduces carrier collection efficiency. This study provides both theoretical and experimental support for the structural design and performance optimization of BIB detectors for low-temperature infrared detection.
Infrared detectors are indispensable in the civilian, military, and aerospace fields, and their future develop- ment is of great strategic significance. This paper reviews the history and current status of infrared detectors, focusing on traditional photon-type infrared detectors such as mercury cadmium telluride (HgCdTe), indium gallium arsenide (InGaAs), antimonides, quantum wells (QWs) and silicon-based blocked impurity band (BIB) detectors. It also covers novel detectors, including colloidal quantum dots (CQDs), two-dimensional (2D) material detectors, electro- magnetic induced well (EIW) effect detectors, and ferroelectric polarization-regulated infrared detectors. Additional- ly, it discusses the applications of new technologies in infrared detection, such as event-based dynamic vision sens- ing, computational imaging, absorption enhanced micro/nanostructures, and three-dimensional (3D) integration. Fi- nally, it explores future development trends of infrared detectors.
To address the need for infrared polarization detection in high-speed aerial targets, this paper presents a prag- matic method for calculating and simulating the infrared polarization characteristics of these targets. Based on a hybrid radiation polarization model, an infrared degree of linear polarization (DoLP) calculation framework for aerial targets and an instantiating method for typical materials are developed. This model framework considers thermal emission, so- lar and environmental radiation reflections, and atmospheric transport effects. The deviations between the calculated and measured DoLP values for the material samples are less than 10%. Using the high-speed SR-72 reconnaissance air- craft as an example, the simulation process is based on the reflection/radiance vector data generated by the polarization calculation model of the target material. The real-time simulation of the SR-72 target's infrared polarization characteris- tics is implemented with the Unity3D engine, and the image frame rate reaches 35 frames per second. The DoLP images of the SR-72 were simulated under varying conditions, including flight speed, detection band (MWIR/LWIR), and so- lar illumination. The variations in its polarization characteristics were subsequently analyzed. This study provides a data foundation and simulation support for infrared polarization detection and related assessment applications of aerial tar- gets.
Unmanned aerial vehicle (UAV) detection holds significant value in both civilian and military domains; how- ever, conventional infrared detection systems remain vulnerable to background clutter interference. Infrared polariza- tion imaging technology offers a novel solution by integrating polarization data with infrared imaging. However, the dif- ferences between polarization and infrared images introduce new problems to target extraction. Therefore, we propose a new detection algorithm based on a scale-adaptive local extreme measure (ALEM). The algorithm introduces an en- hanced SUSAN operator to quickly extract regions of interest (ROIs) while estimating potential target scales within these regions. Then, we present the ALEM algorithm, which is specifically designed to exploit the unique characteris- tics of polarization images. The algorithm effectively measures contrast by analyzing pixel neighborhood features within polarization images. Experimental results based on a real-world polarization image dataset demonstrate that: the signalto-noise ratio gain of the algorithm is increased by 2. 7 times, the background suppression factor is increased by 8. 6 times, and it can run at 20 fps. It exhibits excellent detection performance, robustness, and the capability for real-time detection.
Mid-wavelength infrared (MWIR) imaging technology plays a crucial role in aerospace, medical diag & hybull; nostics, and autonomous driving. Van der Waals material black phosphorus (BP) exhibits exceptionally high car & hybull; rier mobility and an ideal direct bandgap, making it a proven candidate for high-performance room-temperature MWIR sensing. However, the stringent growth conditions and anisotropic growth characteristics restrict the devel & hybull; opment of BP optoelectronic devices to small-scale laboratory demonstrations. Therefore, there is an urgent need to develop large-scale, uniform, and high-performance BP photodetector arrays. This study employed a room temperature preparation technique to deposit a large-area, uniform, low-oxidation BP ink film onto thin-film tran & hybull; sistors, resulting in the development of a 64 & times; 64 high-performance MWIR snapshot photodetector array. The room temperature ink preparation process effectively prevents the oxidation of BP during fabrication, achieving an oxidation loss as low as 1. 12%. In addition, a gradient centrifugation strategy was employed to optimize the later & hybull; al size and thickness distribution of the nanosheets in the BP ink, thereby facilitating the transport of charge carri & hybull; ers. The BP ink film array demonstrated a high photoresponsivity of 4. 52 mA/W in the MWIR range, with pixel light response non-uniformity as low as 10. 1%. This study presents a new approach for advancing large-scale MWIR imaging technology.
A long wave cadmium telluride mercury 1024 & times;768(10 mu m) focal plane detector assembly was prepared by ar- senic ion implantation p-on-n planar junction technology. The cutoff wavelength of the device is 9. 61 mu m at 77 K . The basic performance of the detector assembly was characterized under half well filling level condition, and the results showed that the non-uniformity of the responsivity was 4. 15%, the average NETD was 28. 5mK, and the operability was 99. 81%. A dedicated metal micro-structure was designed and prepared on the surface of a LW MCT 1024 & times;768(10 mu m) focal plane detector chip set, and the crosstalk between pixels was characterized and analyzed. The results showed that device crosstalk was 12. 3%, and the MTF was 0. 35. Finally, imaging demonstrations of outdoor scene and indoor person were conducted with the detector assembly, both of which showed good imaging effect.
