SBIR-STTR Award

For this SBIR program, we propose to demonstrate a solid state short-wave infrared (SWIR) detector technology with true single photon sensitivity with a cutoff wavelength of at least 2.2 um suitable for integration into large-format focal plane arrays (FPAs). Array pixel designs will include self-quenching negative feedback avalanche diode (NFAD) structures with demonstrated single photon response consisting of avalanche pulses providing effective gains of 10^5 to 10^6 charges. These NFAD avalanche pulses also provide extremely reproducible quantized charge packets characterized by charge excess noise of ~1.08. Extended wavelength response to 2.2 um will be achieved using a novel Type II superlattice absorber that is lattice-matched to InP. The ability to realize this extended wavelength response with an absorber lattice-matched to InP provides high material quality (i.e., low dark count rate) and facilitates the incorporation of best-in-class device design elements already proven for our InP-based single photon detectors operating in Geiger mode, such as the NFAD structures. This approach also ensures a rapid integration of these novel 2.2 um pixel designs into large-format arrays that leverage our past success in realizing high-performance arrays of Geiger-mode avalanche diodes as large as 128 x 32.

Benefit:
High performance imaging technology is well-established at visible and near-infrared wavelengths as well as at mid-wave and long-wave infrared regions of the optical spectrum. However, at present there is a notable absence of high-gain, low-light level, large-format sensor technology that is capable of covering the short-wave infrared (SWIR) spectral band between 1 and 2.5 um. In general, there is a fundamental drive in the defense community for the broadest possible situational awareness provided by the availability of sensing technologies over the widest possible range of imaging wavelengths, and filling the current gap in the SWIR band is a priority. Although unity gain (p-i-n) and low gain (linear mode avalanche diode) SWIR detectors exist, these have not been able to address the looming technological obsolesence of legacy low-light level imaging solutions (e.g., vacuum tube-based image intensifiers). Improved, out-of-band low-light level sensors have the potential for dramatic impact in night vision applications, particularly in the defense arena, but also for users in other fields such as law enforcement, border control, and homeland security. The new capabilities to be provided by these sensors for true single photon sensitivity through most of the SWIR band (to 2.2 um) will also benefit various commercial applications within the areas of industrial process control, manufacturing quality assurance, and medical diagnostics.

Keywords:
Short-wave infrared, Short-wave infrared, indium phosphide, superlattice, negative feedback, Avalanche photodiode, Low light level imaging, single photon detector, focal plane array

Princeton Lightwave proposes to develop a solid state short-wavelength infrared (SWIR) detector technology with true single photon sensitivity and a cutoff wavelength beyond 2.2 um. Both single photon avalanche diodes (SPADs) and negative feedback avalanche diodes (NFADs) will be fabricated. These detectors can be readily integrated into large-format focal plane arrays (FPAs), and array format of 32 x 32, 128 x 32 and 128 x 128 will be fabricated. Both active and passive imaging capability of these array devices will be demonstrated. Extended wavelength response to 2.2 um and beyond will be achieved using a novel type II superlattice absorbers grown on InP substrates. Planar-geometry diffused-junction device structure will be adopted for fabricating these devices, which will lead to low dark count rate and long term device stability. To carry out the proposed development work, we will leverage our past success in manufacturing industry best-in-class InP based SPADs and NFADs and the realization of high-performance arrays of Geiger-mode avalanche diodes as large as 128 x 32. The detector technology to be developed will provide a unique solution to many applications that require single photon level sensitivity across the full SWIR spectral band.

Benefit:
High performance imaging technology is well-established at visible and near-infrared wavelengths as well as at mid-wave and long-wave infrared regions of the optical spectrum. However, at present there is a notable absence of high-gain, low-light level, large-format sensor technology that is capable of covering the short-wave infrared (SWIR) spectral band between 1 and 2.5 um. In general, there is a fundamental drive in the defense community for the broadest possible situational awareness provided by the availability of sensing technologies over the widest possible range of imaging wavelengths, and filling the current gap in the SWIR band is a priority. Although unity gain (p-i-n) and low gain (linear mode avalanche diode) SWIR detectors exist, these have not been able to address the looming technological obsolescence of legacy low-light level imaging solutions (e.g., vacuum tube-based image intensifiers). Improved, out-of-band low-light level sensors have the potential for dramatic impact in night vision applications, particularly in the defense arena, but also for users in other fields such as law enforcement, border control, and homeland security. The new capabilities to be provided by these sensors for true single photon sensitivity through the full SWIR band will also benefit various commercial applications within the areas of industrial process control, manufacturing quality assurance, vehicle navigation, and medical diagnostics.

Keywords:
indium phosphide, Short-wave infrared, negative feedback, Avalanche photodiode, superlattice, focal plane array, Low light level imaging, single photon detector