Applications for short-wave infrared sensors continue to increase in commercial and military applications. Reducing pixel pitch decreases the size and cost expanding the ability to deploy sensors on smaller platforms including handheld and autonomous vehicles. Small pixel pitch cameras allow the user to shrink the lens thereby shrinking the total system size. Attollo Engineering will present the development of a VGA SWIR camera with 5 micron pixel pitch. Attollo will discuss designs of the components including detector, ROIC, and camera electronics. Attollo will show imagery and characteristics of the sensor.
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.
Attollo Engineering will present results of our research program developing extended SWIR sensors as well as the packaging and camera electronics surrounding it. The 640x512 sensor uses GaInAsSb for the active layer and has a cutoff wavelength of 2.5 m. 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 m 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.
Next-generation Infrared Focal Plane Arrays (IRFPAs) are demonstrating ever increasing frame rates, dynamic range,
and format size, while moving to smaller pitch arrays.1 These improvements in IRFPA performance and array format
have challenged the IRFPA test community to accurately and reliably test them in a Hardware-In-the-Loop environment
utilizing Infrared Scene Projector (IRSP) systems. The rapidly-evolving IR seeker and sensor technology has, in some
cases, surpassed the capabilities of existing IRSP technology.
To meet the demands of future IRFPA testing, Santa Barbara Infrared Inc. is developing an Infrared Light Emitting
Diode IRSP system. Design goals of the system include a peak radiance >2.0W/cm2/sr within the 3.0-5.0μm waveband,
maximum frame rates >240Hz, and >4million pixels within a form factor supported by pixel pitches ≤32μm. This paper
provides an overview of our current phase of development, system design considerations, and future development work.
In this paper we present first results from a backside illuminated CMOS image sensor that we fabricated on high resistivity silicon. Compared to conventional CMOS imagers, a thicker photosensitive membrane can be depleted when using silicon with low background doping concentration while maintaining low dark current and good MTF performance. The benefits of such a fully depleted silicon sensor are high quantum efficiency over a wide spectral range and a fast photo detector response. Combining these characteristics with the circuit complexity and manufacturing maturity available from a modern, mixed signal CMOS technology leads to a new type of sensor, with an unprecedented performance spectrum in a monolithic device. Our fully depleted, backside illuminated CMOS sensor was designed to operate at integration times down to 100nsec and frame rates up to 1000Hz. Noise in Integrate While Read (IWR) snapshot shutter operation for these conditions was simulated to be below 10e- at room temperature. 2×2 binning with a 4× increase in sensitivity and a maximum frame rate of 4000 Hz is supported. For application in hyperspectral imaging systems the full well capacity in each row can individually be programmed between 10ke-, 60ke- and 500ke-. On test structures we measured a room temperature dark current of 360pA/cm2 at a reverse bias of 3.3V. A peak quantum efficiency of 80% was measured with a single layer AR coating on the backside. Test images captured with the 50μm thick VGA imager between 30Hz and 90Hz frame rate show a strong response at NIR wavelengths.
FLIR Electro Optical Components will present our latest developments in large InGaAs focal plane arrays, which are
used for low light level imaging in the short wavelength infrared (SWIR) regime. FLIR will present imaging from their
latest small pitch (15 μm) focal plane arrays in VGA and High Definition (HD) formats. FLIR will present
characterization of the FPA including dark current measurements as well as the use of correlated double sampling to
reduce read noise. FLIR will show imagery as well as FPA-level characterization data.
We describe the factors that go into the component choices for a short wavelength (SWIR) imager, which include the
SWIR sensor, the lens, and the illuminator. We have shown the factors for reducing dark current, and shown that we can
achieve well below 1.5 nA/cm2 for 15 μm devices at 7°C. We have mated our InGaAs detector arrays to 640x512
readout integrated integrated circuits (ROICs) to make focal plane arrays (FPAs). In addition, we have fabricated high
definition 1920x1080 FPAs for wide field of view imaging. The resulting FPAs are capable of imaging photon fluxes
with wavelengths between 1 and 1.6 microns at low light levels. The dark current associated with these FPAs is
extremely low, exhibiting a mean dark current density of 0.26 nA/cm2 at 0°C. FLIR has also developed a high definition,
1920x1080, 15 um pitch SWIR sensor. In addition, FLIR has developed laser arrays that provide flat illumination in
scenes that are normally light-starved. The illuminators have 40% wall-plug efficiency and provide low-speckle
illumination, provide artifact-free imagery versus conventional laser illuminators.
We describe the factors that go into the component choices for a short wavelength IR (SWIR) imager, which include the SWIR sensor, the lens, and the illuminator. We have shown the factors for reducing dark current, and shown that we can achieve well below 1.5 nA/cm2 for 15 μm devices at 7 °C. In addition, we have mated our InGaAs detector arrays to 640×512 readout integrated integrated circuits to make focal plane arrays (FPAs). The resulting FPAs are capable of imaging photon fluxes with wavelengths between 1 and 1.6 μm at low light levels. The dark current associated with these FPAs is extremely low, exhibiting a mean dark current density of 0.26 nA/cm2 at 0 °C. Noise due to the readout can be reduced from 95 to 57 electrons by using off-chip correlated double sampling. In addition, Aerius has developed laser arrays that provide flat illumination in scenes that are normally light-starved. The illuminators have 40% wall-plug efficiency and provide low-speckle illumination, and provide artifact-free imagery versus conventional laser illuminators.
Aerius Photonics will present their latest developments in large InGaAs focal plane arrays, which are used for low light
level imaging in the short wavelength infrared (SWIR) regime. Aerius will present imaging in both 1280x1024 and
640x512 formats. Aerius will present characterization of the FPA including dark current measurements. Aerius will
also show the results of development of SWIR FPAs for high temperaures, including imagery and dark current data.
Finally, Aerius will show results of using the SWIR camera with Aerius' SWIR illuminators using VCSEL technology.
Short wavelength IR imaging using InGaAs-based FPAs is shown. Aerius demonstrates low dark current in InGaAs
detector arrays with 15 μm pixel pitch. The same material is mated with a 640x 512 CTIA-based readout integrated
circuit. The resulting FPA is capable of imaging photon fluxes with wavelengths between 1 and 1.6 microns at low light
levels. The mean dark current density on the FPAs is extremely low at 0.64 nA/cm2 at 10°C. Noise due to the readout
can be reduced from 95 to 57 electrons by using off-chip correlated double sampling (CDS). In addition, Aerius has
developed laser arrays that provide flat illumination in scenes that are normally light-starved. The illuminators have
40% wall-plug efficiency and provide speckle-free illumination, provide artifact-free imagery versus conventional laser
Recent advances in Vertical-cavity Surface-emitting Laser (VCSEL) efficiency and packaging have opened up
alternative applications for VCSELs that leverage their inherent advantages over light emitting diodes and edge-emitting
lasers (EELs), such as low-divergence symmetric emission, wavelength stability, and inherent 2-D array fabrication.
Improvements in reproducible highly efficient VCSELs have allowed VCSELs to be considered for high power and high
brightness applications. In this talk, Aerius will discuss recent advances with Aerius' VCSELs and application of these
VCSELs to miniature optical sensors such as rangefinders and illuminators.
Aerius Photonics has developed large InGaAs arrays (1K x 1K and greater) with low dark currents for use
in night vision applications in the SWIR regime. Aerius will present results of experiments to reduce the
dark current density of their InGaAs detector arrays. By varying device designs and passivations, Aerius
has achieved a dark current density below 1.0 nA/cm2 at 280K on small-pixel, detector arrays. Data is
shown for both test structures and focal plane arrays. In addition, data from cryogenically cooled InGaAs
arrays will be shown for astronomy applications.
The next generation of low-cost smart munitions will be capable of autonomously detecting and identifying targets aided partly by the ability to image targets with compact and robust scanning rangefinder and LADAR capabilities. These imaging systems will utilize arrays of high performance, low-cost semiconductor diode lasers capable of achieving high peak powers in pulses ranging from 5 to 25 nanoseconds in duration. Aerius Photonics is developing high-power Vertical-Cavity Surface-Emitting Lasers (VCSELs) to meet the needs of these smart munitions applications. The authors will report the results of Aerius' development program in which peak pulsed powers exceeding 60 Watts were demonstrated from single VCSEL emitters. These compact packaged emitters achieved pulse energies in excess of 1.5 micro-joules with multi kilo-hertz pulse repetition frequencies. The progress of the ongoing effort toward extending this performance to arrays of VCSEL emitters and toward further improving laser slope efficiency will be reported.
Standards activities for the next generation of Ethernet, 10 Gigabit Ethernet, are underway. Vertical Cavity Surface Emitting Lasers (VCSELs) offer significant advantages for realizing cost-effective, high speed optical data links. The progress towards achieving 10 Gb/s VCSEL-based links is reviewed.
Vertical cavity surface emitting lasers (VCSELs) operating near 1310 or 1550 nm have been the subject of intensive research by multiple groups for several years. In the past year at Gore, we have demonstrated the first 1300 nm VCSELs which operate with useful power, high modulation rate, and low voltage over the commercial temperature range of 0 - 70 degree(s)C. These results have been achieved using a new structure in which an 850 nm VCSEL optical pump is integrated with the 1300 nm VCSEL. Electrical drive is applied to the 850 nm pump, and 1300 nm light is emitted from the integrated structure. This approach has resulted in over a milliwatt of single transverse mode power at room temperature, and several hundred microwatts of single transverse mode power at 70 degree(s)C. In addition, these devices demonstrate multi-gigabit modulation and excellent coupling efficiency to single-mode fiber.
Low threshold current single quantum well InGaAs/GaAs lasers are fabricated by metalorganic chemical vapor deposition on a nonplanar substrate. By taking advantage of the growth rate and doping differences on different crystal facets during the growth, an almost- buried heterostructure laser is made by a single growth step. Threshold currents as low as 1.0 mA under pulsed operation and 1.2 mA under continuous-wave operation are obtained for uncoated lasers at room-temperature. The lasers showed high external quantum efficiency (80%). High reflection coated laser (95%/95%) has a cw threshold current as low as 0.28 mA.