双光栅夹有机溶液构成的宽带光限幅器

Broadband Optical Limiter with an Organic Solution Sandwiched Between Two Gratings

提出一种新型的光限幅器件并给出初步的实验验证．该器件是将非线性有机溶液夹在两块不同的浮雕型透射光栅之间构成的．溶液的折射率与光栅材料匹配，器件对普通光透射率很高．但在强激光照射下，液体吸热汽化，折射率失配而显露光栅．入射光被前面的光栅全反射和散射，再经有机液体吸收、散射和自散焦，最后被后面的光栅消去零级衍射，使可见光波段的透射能量低于人眼损伤极限，从而有效地防护眼睛免受宽带脉冲激光的伤害．

A novel optical limiting device is proposed. The device consists of an organic solution sandwiched between two transmitted relief gratings with different grove sturcture. The refraction index of the liquid is matched with that of grating material. The device has a high transmittance under the common light. However, the strong laser will make the liquid to thermally vaporize, index mismatch, and two gratings appear. The incident light will be total reflected and scattered by the front grating, then it will be strongly absorbed, scattered and self focused by the organic solution. Finally, the rear grating will suppress the zero order diffraction, let the transmitted light energy lower than the damage threshold of human eyes. Therefore, the device provides an effective protection of eyes against the broadband pulsed laser damage.