Not quite as simple as that. Terahertz != Short Wave Infrared != Midwave Infrared != Longwave Infrared ("thermal"). These all require different photosensitive e

Not quite as simple as that. Terahertz != Short Wave Infrared != Midwave Infrared != Longwave Infrared ("thermal"). These all require different photosensitive elements in your detector. They also have extremely different atmospheric absorptions. [1] These particular sensors might indeed be passive, but it would limit their range and SNR. Be wary of manufacturers simply selling the emitter as a second SKU to garner the label passive on their detectors. [1] I work at a company making SWIR/MWIR imagers.