Size, Weight, And Power Consumption Research Articles

Room-Temperature (RT) Extended Short-Wave Infrared (e-SWIR) Avalanche Photodiode (APD) with a 2.6 µm Cutoff Wavelength.

Highly sensitive infrared photodetectors are needed in numerous sensing and imaging applications. In this paper, we report on extended short-wave infrared (e-SWIR) avalanche photodiodes (APDs) capable of operating at room temperature (RT). To extend the detection wavelength, the e-SWIR APD utilizes a higher indium (In) composition, specifically In0.3Ga0.7As0.25Sb0.75/GaSb heterostructures. The detection cut-off wavelength is successfully extended to 2.6 µm at RT, as verified by the Fourier Transform Infrared Spectrometer (FTIR) detection spectrum measurement at RT. The In0.3Ga0.7As0.25Sb0.75/GaSb heterostructures are lattice-matched to GaSb substrates, ensuring high material quality. The noise current at RT is analyzed and found to be the shot noise-limited at RT. The e-SWIR APD achieves a high multiplication gain of M~190 at a low bias of Vbias=- 2.5 V under illumination of a distributed feedback laser (DFB) with an emission wavelength of 2.3 µm. A high photoresponsivity of R>140 A/W is also achieved at the low bias of Vbias=-2.5 V. This type of highly sensitive e-SWIR APD, with a high internal gain capable of RT operation, provides enabling technology for e-SWIR sensing and imaging while significantly reducing size, weight, and power consumption (SWaP).

Infrared HOT Photodetectors: Status and Outlook.

At the current stage of long-wavelength infrared (LWIR) detector technology development, the only commercially available detectors that operate at room temperature are thermal detectors. However, the efficiency of thermal detectors is modest: they exhibit a slow response time and are not very useful for multispectral detection. On the other hand, in order to reach better performance (higher detectivity, better response speed, and multispectral response), infrared (IR) photon detectors are used, requiring cryogenic cooling. This is a major obstacle to the wider use of IR technology. For this reason, significant efforts have been taken to increase the operating temperature, such as size, weight and power consumption (SWaP) reductions, resulting in lower IR system costs. Currently, efforts are aimed at developing photon-based infrared detectors, with performance being limited by background radiation noise. These requirements are formalized in the Law 19 standard for P-i-N HgCdTe photodiodes. In addition to typical semiconductor materials such as HgCdTe and type-II AIIIBV superlattices, new generations of materials (two-dimensional (2D) materials and colloidal quantum dots (CQDs)) distinguished by the physical properties required for infrared detection are being considered for future high-operating-temperature (HOT) IR devices. Based on the dark current density, responsivity and detectivity considerations, an attempt is made to determine the development of a next-gen IR photodetector in the near future.

Hybrid Navigation Prototype for Small Aircraft Transportation Vehicles

The Small Aircraft Transportation (SAT) segment represented mainly by helicopters, piston fixed-wing aircraft, turboprop aircraft, and business jets requires a reliable source of navigation information with an appropriate price. This paper describes the research and development activity funded by Clean Sky 2 Cost Optimized Avionic Systems (COAST) development program targeting affordable hybrid navigation solutions. The affordability is driven by size, weight, and power consumption (SWAP) requirements. The desired level of accuracy, integrity, and availability is being achieved by a hybrid navigation solution based on GPS/INS fusion extended by other navigation sensors. The hybrid core of the systems uses GPS with SBAS augmentation to outperform standard tightly coupled GPS-based hybrid systems. The purpose of this article is to describe the current state, algorithmic structure, and hardware maturity of the navigation system prototype. The paper describes individual hardware components, points to the resulting prototype, and summarizes tests in a representative environment. The ultimate goal is to demonstrate the overall performance of the hybrid system based on a low-cost micro-electro-mechanical system (MEMS) Inertial Measurement Unit (IMU). The low-cost inertial sensor is one of the key components securing the affordability of the proposed system, so its testing plays important role. Another assumption considered in the system design was integration of standardly-used onboard sensors. For this purpose, the hardware prototype was tested in a demonstrative and outdoor environment. The results of this exercise are summarized in this paper.

Vernier microcombs for high-frequency carrier envelope offset and repetition rate detection

Recent developments in Kerr microcombs may pave the way to a future with fully stabilized ultralow size, weight, and power consumption (SWaP) frequency combs. Nevertheless, Kerr microcombs are still hindered by a bandwidth/repetition rate trade-off. That is, the octave bandwidth needed for self-referencing is typically realized only with ∼THz repetition rates beyond the range of standard commercial photodetectors. The carrier envelope offset frequency is often likewise too high for detection. Dual-comb techniques for the measurement of THz repetition rates have made exciting progress, but the fCEO detection problem remains largely unaddressed. In this work, utilizing a Vernier dual-comb configuration, we demonstrate simultaneous detection of the electronically divided repetition rate and fCEO carrier envelope offset frequency of an octave-spanning microcomb. This, in turn, could help usher optical atomic clocks, low-noise microwave generators, and optical frequency synthesizers into various real-world applications.

High-resolution and a wide field-of-view eye-safe LiDAR based on a static unitary detector for low-SWaP applications.

High three-dimensional (3D) resolution for a wide field-of-view (FoV) is difficult in LiDARs because of the restrictions concerning size, weight, and power consumption (SWaP). Using a static unitary detector (STUD) approach, we developed a photodetector and a laser module for a LiDAR. Utilizing the fabricated photodetector and laser module, a LaserEye2 LiDAR prototype for low-SWaP applications was built using the STUD approach, which efficiently enables short-pulse detection with the increased FoV or large photosensitive area. The obtained 3D images demonstrated a diagonal FoV of > 31°, a frame rate of up to 15 Hz, and a spatial resolution of 320 × 240 pixels within a detection range of > 55 m. This prototype can be applied to drones to rapidly detect small or thin hazardous objects such as power lines.

Fully integrated hybrid microwave photonic receiver

Microwave photonic receivers are a promising candidate in breaking the bandwidth limitation of traditional radio-frequency (RF) receivers. To further balance the performance superiority with the requirements regarding size, weight, and power consumption (SWaP), the implementation of integrated microwave photonic microsystems has been considered an upgrade path. However, up to now, to the best of our knowledge, chip-scale fully integrated microwave photonic receivers have not been reported due to the limitation of material platforms. In this paper, we report a fully integrated hybrid microwave photonic receiver (FIH-MWPR) obtained by comprising the indium phosphide (InP) laser chip and the monolithic silicon-on-insulator (SOI) photonic circuit into the same substrate based on the low-coupling-loss micro-optics method. Benefiting from the integration of all optoelectronic components, the packaged FIH-MWPR exhibits a compact volume of 6 cm 3 and low power consumption of 1.2 W. The FIH-MWPR supports a wide operation bandwidth from 2 to 18 GHz. Furthermore, its RF-link performance to down-convert the RF signals to the intermediate frequency is experimentally characterized by measuring the link gain, the noise figure, and the spurious-free dynamic range metrics across the whole operation frequency band. Moreover, we have utilized it as a de-chirp receiver to process the broadband linear frequency-modulated (LFM) radar echo signals at different frequency bands (S-, C-, X-, and Ku-bands) and successfully demonstrated its high-resolution-ranging capability. To the best of our knowledge, this is the first realization of a chip-scale broadband fully integrated microwave photonic receiver, which is expected to be an important step in demonstrating the feasibility of all-integrated microwave photonic microsystems oriented to miniaturized application scenarios.

UWB Fastly–Tunable 0.5–50 GHz RF Transmitter Based on Integrated Photonics

Currently, due to the 6G revolution, applications ranging from communication to sensing are experiencing an increasing and urgent need of software-defined ultra-wideband (UWB) and tunable radio frequency (RF) apparatuses with low size, weight, and power consumption (SWaP). Unfortunately, the coexistence of ultra-wideband and software-defined operation, tunability and low SWaP represents a big issue in the current RF technologies. Recently, photonic techniques have been demonstrated to support achieving the desired features when applied in RF UWB transmitters, introducing extremely wide operation and instantaneous bandwidth, tunable filtering, tunable photonics-based microwave mixing with very high port-to-port isolation, and intrinsic immunity to electromagnetic interferences. Moreover, the recent advances in photonics integration also allow to obtain very compact devices. In this article, to the best of our knowledge, the first example of a complete tunable software-defined RF transmitter with low footprint (i.e., on photonic chip) is presented exceeding the state-of-the-art for the extremely large tunability range of 0.5–50 GHz without any parallelization of narrower-band components and with fast tuning (<200 μs). This first implementation represents a breakthrough in microwave photonics.

Multitasking and Cascadable Microwave Photonic Signal Processing Topologies with Silicon Photonic Technologies

ABSTRACT Microwave photonics (MWPs) is an emerging interdisciplinary field, where photonics technologies are adopted to facilitate the generation, transmission, detection, and processing of signals at radio-wave, microwave, and millimeter-wave frequencies. Recently, the integrated photonic technology has demonstrated its capability to miniaturize photonic circuits on a single chip, which paves the way for next-generation integrated MWP signal processing systems having reduced size, weight, and power consumption (SWaP) specifications. In particular, by means of incorporating complementary metal-oxide-semiconductor (CMOS) electronic, optical, and optoelectronic components on a single integrated chip, silicon photonic circuits have brought new architectures and functionalities for MWP signal processing. This accelerates the evolution of MWPs from a single-use microwave signal processor toward a multitasking and cascadable MWP system, which is readily adaptable for a wide variety of uses and applications. In this review article, we provide an overview of the fundamental principle of the MWP signal processing topology. Developments in the microwave filtering technologies are reviewed with a focus on the integrated microwave filtering enhanced by optical phase equalization. We also review the recent progress and give an outlook for the future trend in MWP signal topologies, exploring the realization of multitasking and cascadable microwave signal processing systems based on silicon photonics.

Size, weight, and power reduction of mercury cadmium telluride infrared detection modules

Application requirements driving present IR technology development activities are improved capability to detect and identify a threat as well as the need to reduce size weight and power consumption (SWaP) of thermal sights. In addition to the development of 3rd Gen IR modules providing dual-band or dual-color capability, AIM is focused on IR FPAs with reduced pitch and high operating temperature for SWaP reduction. State-of-the-art MCT technology allows AIM the production of mid-wave infrared (MWIR) detectors operating at temperatures exceeding 120 K without any need to sacrifice the 5-μm cut-off wavelength. These FPAs allow manufacturing of low cost IR modules with minimum size, weight, and power for state-of-the-art high performance IR systems. AIM has realized full TV format MCT 640×512 mid-wave and long-wave IR detection modules with a 15-μm pitch to meet the requirements of critical military applications like thermal weapon sights or thermal imagers in unmanned aerial vehicles applications. In typical configurations like an F/4.6 cold shield for the 640×512 MWIR module an noise equivalent temperature difference (NETD) <25 mK @ 5 ms integration time is achieved, while the long-wavelength infrared (LWIR) modules achieve an NETD <38 mK @ F/2 and 180 μs integration time. For the LWIR modules, FPAs with a cut-off up to 10 μm have been realized. The modules are available either with different integral rotary cooler configurations for portable applications that require minimum cooling power or a new split linear cooler providing long lifetime with a mean time to failure (MTTF) > 20000, e.g., for warning sensors in 24/7 operation. The modules are available with optional image processing electronics providing nonuniformity correction and further image processing for a complete IR imaging solution. The latest results and performance of those modules and their applications are presented.