白色光励起表面プラズモンセンサの感度向上に関する基礎研究(学内特別研究および国外研修,学内特別研究費報告書)白色光励起表面プラズモンセンサの感度向上に関する基礎研究(学内特別研究および国外研修,学内特別研究費報告書) Study on improving a surface plasmon sensor in white light excitation(Researches and Overseas Activities,Research Reports)
Surface plasmon polaritons are collective oscillation of the free electron on the metal surface, which can be excited by optical waves. The excitation is affected by media on the surface, and the affection is applied for sensors. When the surface plasmon polaritons are excited, the optical waves are confined on the surface, thus it is expected that the sensitivity of the sensor becomes higher. We are developing the sensor having both sensitivity and simplicity to observe the medium. The scheme of the sensor is the following. The surface plasmon polaritons are excited by white light. The light of color fulfilling the excitation condition with the medium excites surface plasmon polaritons. We observe a color of the excited surface plasmon polaritons and measure the concentration of the medium. The color is observed through the light waves, which is converted from surface plasmon polaritons. The rough surface of the metal converts surface plasmon polaritons, which is non-radiative, to propagative light waves. The rough surface not only converts them but also disturbs the excitation of the surface plasmon polaritons. The disturbance widens the spectral width of the surface plasmon polaritons, and sensitivity become worth worse. We have researched about the relationship between the spectral width and the roughness of the surface for the work to improve the sensor sensitivity.