Research Papers

Research plays a vital role in fueling our competitive engine at Attollo Engineering. We recognize its importance and emphasize its value. Below, you will find a selection of our most recent publications, showcasing our dedication to advancing knowledge.

Small pixel pitch, high-definition MWIR, and dual band SWIR/MWIR imaging sensors for SWaP constrained applications

Author: Andrew Hood, Edward Huang, Kai Yang, Dustin Hibberd, Vince Loung, et al

Published in: SPIE Digital Library

Date: 13 June 2023

Abstract: Unmanned airborne and dismounted soldier capability requirements continue to push for reduced size, weight, and power (SWaP) and high sensitivity infrared (IR) imaging in applications that were not previously practical. In response to these needs, Attollo Engineering has developed a 1280×1024, 5 µm pixel pitch cooled mid wavelength infrared (MWIR) sensor that pushes the envelope in pixel pitch in addition to a 1280×1024, 10 µm pixel sensor dual band sensor with additional sensitivity in the short wavelength infrared (SWIR) in order to exploit SWIR phenomenology including laser see spot functionality. Both of these sensors offer MWIR sensing capabilities but are also able to leverage aspects of Attollo’s detector design to enable SWIR sensing to varying degrees. This class of small pixel cooled, single and dual band IR sensor technology represents advancements in all aspects of the sensor’s design and development, and we will discuss the innovations made at Attollo to enable this capability including epitaxial detector design based on III V compound semiconductors, detector array and focal plane array fabrication, design of a low noise, dual band CTIA/DI readout integrated circuit (ROIC), vacuum dewar packaging, and electronics and firmware design. In this paper we will present on the status of high definition small pixel pitch MWIR and dual band SWIR/MWIR imaging technology at Attollo as it relates to these sensors including design and measurement data and imaging.

Small pixel MWIR sensors for low SWaP applications

Author: Ed Huang, Jeremy Thomas, Dustin Hibberd, Vince Luong, Randall Lott, et al

Published in: SPIE Digital Library

Date: 21 April 2021

Abstract: Small pixel pitch sensors offer opportunities for imaging system SWaP reduction that open up a variety of SWaP constrained applications that were not previously feasible. Furthermore, small pixel digital sensors provide advantages in the form of additional SWaP reduction, noise immunity, and simplified interfacing requirements. With these motivations in mind, Attollo Engineering has developed a 640×512, 5µm pixel pitch, high operating temperature MWIR sensor based on III V compound semiconductor detector materials. We have adapted our 5µm pixel pitch SWIR processes for MWIR detector materials and have been able to achieve 99.5+% operability MWIR FPAs with BLIP performance operating at 130K. Additionally, we have developed a compact camera core with an integrated cooler and full featured camera electronics. The global shutter camera is capable of frame rates of up to 220 Hz or smaller windows in excess of 1 kHz and integration times as low as 100 nanoseconds. Attollo will discuss characteristics of this sensor and other related technologies.

Low-Capacitance InGaAs Detectors for High-Speed, Wide Field of View Sensing Applications

Author: Jon Geske, Andrew Hood, Jeremy Thomas, Michael MacDougal

Published in: SPIE Digital Library

Date: 7 May 2019

Abstract: Attollo has developed large area low capacitance InGaAs detectors to meet the needs of LiDAR systems following the roadmap of technology development at the near Infrared (NIR) wavelengths of 850/905/940 nm with the eventual transition to eye-safe wavelengths near 1550 nm. Attollo InGaAs offers large photodetector areas while still meeting the bandwidth limitations of the amplified detection system. Large area photodetectors enable a large system Field of View (FOV) with a simpler and larger diameter lens and also provide lower input-referred noise from optimized transimpedance amplifier systems. Attollo will present results on InGaAs detectors achieving capacitance densities 3x lower than state-of-the-art with 16 pF/mm2. Attollo will present LiDAR receiver modeling data utilizing these detectors and will quantify the advantages of low capacitance in LIDAR applications as it relates to system bandwidth and amplifier input referred noise performance of the system.

Thermoelectrically-cooled extended-SWIR FPAs using unipolar barrier detectors 

Author: Michael MacDougal, Andrew Hood, Jeremy Thomas

Published in: SPIE Digital Library

Date: 9 May 2018

Abstract: Attollo Engineering will present results of our research program developing extended SWIR sensors as well as the packaging and camera electronics surrounding it. The 640×512 sensor uses GaInAsSb for the active layer and has a cutoff wavelength of 2.5 um. The unipolar barrier structure enables a higher operating temperature by substantially reducing dark current caused by G-R mechanisms and surface leakage. The material is grown on GaSb and is made up of GaInAsSb absorber and contact layers separated by an AlGaSb barrier. We will present dark current and imaging results from the sensor fabrication at different temperatures. The detector array was hybridized to a 15 um pixel pitch ROIC that has a direct injection unit cell. The hybridized sensor was packaged into a custom 4-stage thermoelectrically cooled package. The package was particularly designed to minimize the heat load and maximize the thermal conduction. We will present the trades that went into designing the package and the internals of the package. The cooler stabilized the sensor temperature at 200K. The electronics used to drive the package have the ability to change biases and timing on the fly using software controls. Attollo designed these electronics to be a low-cost solution for demonstrating sensors in many different modes. We will show information regarding each stage of integration and show the results of the imaging using the eSWIR sensor and supporting equipment.

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