Shortwave Infrared InGaAs Detectors On-Chip Integrated with Subwavelength Polarization Gratings

Abstract

Shortwave infrared polarization imaging can increase the contrast of the target to the background to improve the detection system’s recognition ability. The division of focal plane polarization indium gallium arsenide (InGaAs) focal plane array (FPA) detector is the ideal choice due to the advantages of compact structure, real-time imaging, and high stability. However, because of the mismatch between nanostructures and photosensitive pixels as well as the crosstalk among the different polarization directions, the currently reported extinction ratio (ER) of superpixel-polarization-integrated detectors cannot meet the needs of high-quality imaging. In this paper, a 1024 × 4 InGaAs FPA detector on-chip integrated with a linear polarization grating (LPG) was realized and tested. The detector displayed good performance throughout the 0.9–1.7 um band, and the ERs at 1064 nm, 1310 nm and 1550 nm reached up to 22:1, 29:1 and 46:1, respectively. For the crosstalk investigation, the optical simulation of the grating-integrated InGaAs pixel was carried out, and the limitation of the ER was calculated. The result showed that the scattering of incident light in the InP substrate led to the crosstalk. Moreover, the deviation of the actual grating morphology from the designed structure caused a further reduction in the ER.

A Super-Resolution Reconstruction Method for Infrared Polarization Images with Sparse Representation of Over-Complete Basis Sets

“…The infrared focal plane polarization detector has garnered significant interest as the central component of infrared polarization imaging. It consists of multiple groups of micro-linear polarization units and infrared detectors [10]. The micro-linear polarization units are arranged in an ordered structure on the surface of the infrared detector, with each group containing four pixels.…”

Modeling of Subwavelength Gratings: Near-Field Behavior

“…These structures offer a cost-effective and compact solution, with potential in manipulating the polarization properties of emitted radiation [7]. They can also enhance the performance of InGaAs infrared polarization imaging [8]. The incorporation of double SWGs has demonstrated promise in creating ultranarrow resonances in the optical response of systems, leading to gain factors of up to 10 5 [9].…”