以隨機共振理論增強反射式表面電漿共振系統之研究

隨機共振理論是描述在非線性的環境中，外加隨機訊號的擾動可以增強微小訊號或增強訊號中所挾帶的訊息。在最佳的雜訊強度下可以增強系統訊號，顛覆傳統中增加雜訊強度只會降低系統的量測能力。隨機共振現象出現的條件必須在非線性系統中而不會出現在嚴謹的線性系統中，在線性系統中加入雜訊只會有降低系統效能的效果。非線性系統可以將雜訊的能量轉移到訊號上，經過非連續性的系統擷取後，增強訊號的頻率成份等有意義的訊息。　　在程式及真實的感測器中驗證隨機共振機制的存在，接著利用自製的表面電漿共振系統驗證在訊號非常微小的情況下，雜訊對於訊號的影響。其中外加的光雜訊是利用被訊號產生器產生的雜訊所驅動的發光二極體加入，探討在真實的感測系統中隨機共振的效果。本實驗的結果證明外加光雜訊可以增加微小訊號的頻率成份，搭配鎖相放大器可以使直流輸出的振幅增加。這種隨機共振的非線性系統可能存在於光電倍增管的二次發射極對光電子的聚焦，在有最佳的雜訊強度中，光電子聚焦在發射極的基數較大且有較高的輸出訊號。　　本研究結合隨機共振與鎖相放大器，提出一個針對微小訊號的量測方式，實驗結果證明雜訊在特定條件下不只有降低系統效能的影響，若以更適合的非線性條件和微小訊號的條件下，隨機共振的機制應可以增強整體系統的感測效果。並且可以嘗試使用隨機共振法量測單分子，相較表面電漿共振系統更微小的訊號。

關鍵字

隨機共振；表面電漿共振；鎖相放大器；微小訊號量測；非線性系統

並列摘要

Stochastic resonance is a nonlinear phenomenon whereby the addition of a random interference can enhance the detection of weak stimuli of a signal. An optimal amount of added noise results in the maximum enhancement, whereas further increases in the noise intensity only degrade detectability or information content. The phenomenon does not occur in strictly linear systems, where the addition of noise to either the system or the stimulus only degrades the measures of signal quality. In this research, this research verified stochastic resonance in program and real sensor. Then applied stochastic resonance mechanism to surface plasmon resonance detection system using the second LED which is driven by function generator white noise. According to our result, the amplitude of weak signal from lock-in amplifier will be improved by adding noise. This effect may be caused because stochastic resonance mechanism appear in photocathode of photomultiplier. This research developed a novel detection method for improving amplitude of weak signal. Stochastic resonance using noise to enhance signal with non-linear system. This method may be applied to weak signal detection such as single molecule detection.

並列關鍵字

stochastic resonance ； SPR ； lock-in amplifier ； weak signal detection ； nonlinear system

參考文獻

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以隨機共振理論增強反射式表面電漿共振系統之研究

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