QWIP: still the best solution for high-end applications in LWIR

Abstract

Quantum well infrared photodetector (QWIP) technology is an excellent solution for tactical applications due to the unmatched image uniformity, stability, and pixel operability (typically <99.9%). IRnova have a high-volume production of QWIP detectors in both QVGA and VGA formats since 1999. In 2017 a VGA format QWIP with 15 μm pitch was released, which has demonstrated excellent sensitivity (expressed as noise equivalent temperature difference (NETD)) of 30 mK at F/2 and 100 Hz frame rate. QWIPs also enable compact designs for polarimetric imaging by implementing polarization-sensitive lamellar gratings directly onto the detector pixels. Such polarimetric LWIR detectors (peak absorption at 8.5 μm) have been fabricated at IRnova as both QVGA and VGA format FPAs on 30 and 15 μm pitch, respectively. Polarimetric imaging with these detectors is demonstrated in this work, showing polarimetric contrast as high as 57±5 % for the QVGA format detectors, while the VGA format arrays provide enhanced spatial resolution at the expense of a lower polarization contrast (≈21±2 %). Finally, to meet the demand of highly sensitive and reliable HD LWIR detectors, a 1280×1024 QWIP detector on 10 μm pitch is the next targeted format of IRnova’s QWIP sensors. In this work, the anticipated performance of such detectors will be presented based on the simulation result using the in-house developed tools. The modelling takes into account the relevant ROIC parameters, as well as scaling of the detector performance with pixel size.