IR and visible wideband protection filter

Imaging and detection systems are susceptible to detector saturation or permanent damage caused by powerful light sources or high power lasers. We propose and demonstrate a passive, solid-state threshold-triggered optical protection filter. At input power below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. As opposed to fixed spectral filters, which permanently block only specific wavelengths, the wideband filter is clear at all wavelengths until it is hit by damaging light. When high incident optical power impinges on the wideband filter at a certain spot, this spot becomes permanently opaque. The wideband protection filter is fast enough to block nanosecond laser pulses.