Broadband Optical Attenuator via Amplified Free Carrier Absorption

The blinding or disabling of focal plane arrays (FPAs) can greatly impair situational awareness for the warfighter. Some passive technologies, such as filters, can selectively remove certain wavelengths if those wavelengths are known to be threats, but there exists a need for a technology that can 1) attenuate 99.9% of high intensity light in a localized region within the viewing area, 2) perform this task at a wavelength that is also of interest to the viewer/camera, and 3) perform this task when the threat wavelength is unknown or tunable. To that end, PSI has developed a technology that uses a novel approach to optical limiting that uses amplified free carriers to attenuate more than 99.9% of a high power incident pulse. An individual device can protect against unknown threats across a broad bandwidth (e.g. the full visible) and the concept can be designed to operate in the visible, near infrared and short wave infrared bands, while exhibiting high transmission in the absence of high-intensity threats.