Nonlinear optical limiters with grating sandwich structure for eye protection

A novel optical limiting device by sandwiching a nonlinear liquid between t wo specially designed diffraction gratings is proposed and demonstrated. Un der low intensity of light, the device has a high transmittance because of index matching between the liquid and grating materials. Strong light beam can induce the nonlinear effects such as reverse saturable absorption, nonl inear scattering and self-defocusing to reduce the transmittance of device. On the other hand, the strong light beam can also change the index of the liquid to induce index mismatch and reactivate the gratings to diffract the output light away from the observed direction to protect eyes. In this pap er, the different gratings with suppressed zero-order diffraction and nonli near liquids are analyzed. The new device provides an effective protection of eyes against the ns-pulsed laser in the visible range.