表面プラズモンの伝搬損失をレーザー光で制御可能

We report a new aspect of surface plasmon polaritons excited on a nonmetallic material pumped with intense femtosecond laser pulses.

[速報] 非金属表面に高強度のフェムト秒レーザーパルスを照射したときに励起される表面プラズモン・ポラリトン（SPP）について、金属表面で励起されるSPPでは見られなかった新しい現象【レーザーパルスエネルギー密度の増加によってプラズモン減衰が減少すること】について報告しました。今後、レーザーパラメータによって自在に非金属表面でのSPPの伝搬をコントロールできるようになることが期待されます。

https://doi.org/10.7567/1347-4065/ab13db

Reduced damping of surface plasmon polaritons on silicon with intense femtosecond laser pulse

Abstract: Using intense p-polarized 100-femtosecond laser pulses, the reflectivity of a silicon grating was measured in air as a function of the incident angle. The angular dependent reflectivity was observed to abruptly decrease to create a sharp dip at a specific incident angle, representing the surface plasmon resonance (SPR) induced on the grating. We have found that the sharpness of the dip increases with increasing the laser fluence. The experimental results show that the increase in the laser fluence produces a higher density of free electrons in the surface and decreases the plasmon damping to enhance the SPR. The calculated reflectivity reproduces well the increase in the dip sharpness with increasing the electron density in the silicon grating surface.

2019.04