Overall sensitivity-improvement performance metric for analysis, comparison and characterization of MWIR strained-layer super-lattice (SLS) photo-detectors enhanced with microsphere lenses of different material structures and sizes

In this paper we propose a technique and an objective performance metric, that we denote "area-metric", for the analysis and overall comparison and characterization of FTIR spectral response sensitivity-improvement performances of strained-layer superlattice (SLS) 3μm-5μm MWIR single photo detectors, enhanced with microsphere lenses of different dielectric material structures and sizes. In this work we use, analyzer, and compare eleven (11) detector FTIR spectral data collected with two different SLS detector sizes of 35μm and 40μm, and four different microsphere material structure types, namely, BTG (Barium Titanate Glass), SLG (Soda-Lime Glass), PS (Polysterene), and Sapphire, with sizes ranging from 90μm to 300μm. Based on the collected data considered in this work, it is shown that the size of the MWIR SLS detector has less effect on the microsphere-lens-enhanced detector overall spectral sensitivity improvement, than the microsphere lens structure type and size have. It is also shown, based on this overall performance area-metric that, in the 3μm-5μm spectral band, the sapphire material structure of size 300μm integrated on an SLS photo-detector of size 40μm outperforms the other considered ten (10) SLS MWIR photo-detectors enhanced with microspheres of different material structure types/sizes. The robustness to noise of the proposed overall performance metric is also shown here.