即時高靈敏度捕捉感測單粒子之混合式光子/電漿子微盤共振腔設計

Abstract

本研究提出了一個藉由通道波導耦合激發的微小化混合式光子/表面電漿子微盤，受益於混合式表面電漿模態與耳語廊模態，此結構對於奈米粒子的操控有很大的潛力，藉由微盤共振腔與表面電漿子的共振特性，高度侷域近場可提高光學鉗制力並降低耗能。模擬顯示，穩定捕捉單顆100奈米的聚苯乙烯粒子僅需20.6毫瓦的波導閥值能量，我們也分析了使粒子位置作轉換的機制，藉由調變入射光於結構共振波長或非共振波長可使粒子傳輸於通道波導或微盤共振腔，此外結構對於單顆粒子也有高靈敏的感測應用，當結構捕捉單顆1微米聚苯乙烯粒子時可造成5%的通道出口能量變化。在實驗方面，我們率先提出此混和式電漿子微盤與波導整合的製程方法，並且利用研磨拋光系統，提出並成功將1200微米長的通道波導入口與出口可以出現在玻璃基板邊緣的方法，未來期望此系統可被實際應用於粒子捕捉與感測分析系統上且達到一同整合於晶片實驗室系統的目標。

We proposed a compact hybrid photonic-plasmonic microdisk excited by a coupling bus waveguide. Benefiting from strong localization of hybrid plasmonic mode and whispering gallery mode in near field region, the design holds potential on nanoparticle trapping. Resonance characteristic of microcavity and plasmonic structure offers a way to enhance optical force and lower power consumption. From simulated results, stable trapping of a 100 nm PS can be achieved with threshold waveguide guided power of 20.6 mW. A particle position switching mechanism is also numerically analyzed by tuning input wavelength at resonance or out of resonance. Moreover, the features provide possibility for single particle size detection with high sensitivity. There is a 5% output power variation when the cavity traps a 1 μm PS particle. In the experiment, we also take the lead and develop a method for fabricating the hybrid photonic-plasmonic microdisk. We also present a way to make the input and output interface of the 1200 µm bus waveguide appear at the sample edge by using polishing platform. We expect the design to be applied in particle manipulation system and sensing application. In the future, the proposed resonator can be integrated with other system to realize lab on a chip.