可調控式隨機雷射之研究

Study of Tunable Random Lasers

楊宇宸(Yu-Chen Yang)

指導教授 ： 洪毓玨

國立清華大學/電機資訊學院/光電工程研究所/碩士(2014年)

摘要

在隨機雷射領域中，如何控制雷射光譜一直是學者們所想要達到的目標，藉由控制隨機雷射可以使我們達到更多的應用與發展。本研究中，我們利用兩種不同的機制來控制隨機雷射。
第一個機制是利用光來控制隨機雷射的行為。我們以具有特殊雙股螺旋結構的去氧核糖核酸（deoxyribonucleic acid，DNA）分子材料，作為銀奈米晶種的生長模板，並運用光還原法，來生成散射介質，也就是銀奈米粒子。我們透過光還原時間的不同來改變銀奈米粒子的大小、形狀及數量，進而改變隨機雷射的特性，並分析激發能量門檻值，放射波長以及振幅傅利葉變換(power Fourier transform)在不同還原時間下的結果。
第二個機制是利用電場的方式來控制隨機雷射。我們會在設計好的平行板結構間隙中，加入含有聚苯乙烯(polystyrene)粒子及雷射染料Rh6G（rhodamine 6G）的溶液，再施加不同大小電場，利用介電泳力的原理，來影響聚苯乙烯粒子的分佈，藉由粒子分佈的不同來影響其隨機雷射光譜模態，同樣的，我們也利用平均自由路徑以及振幅傅利葉變換(power Fourier transform)來分析隨機雷射的行為與外加電場的關係。

關鍵字

隨機雷射 ； 去氧核醣核酸 ； 介電泳

並列摘要

Controlling random laser is tone of the important topics in this field, which may lead to more applications and developments. In this work, we demonstrate the control of random laser by two different mechanisms.
The first mechanism to control the performance of random laser via an optical route. We use a photoreduction method to synthesize silver nanoparticles(NPs) in biopolymer based on deoxyribonucleic acid, which is used as a growing template. The photoreduction time can change the size, shape and number of NPs, and consequently the performance of random laser is changed by optically-controlled scatterers. The pumping energy threshold, emission wavelength and power Fourier transform are analyzed to evaluate the tunability of random lasers with respect to photoreduction time.
The second mechanism is that we utilized electric field to control random laser. We design a structure of parallel plates and add solution mix polystyrene particles and Rh6G（rhodamine 6G）laser dye into gap of parallel plates. Then, different magnitude of electric field is applied to influence the distribution of polystyrene particles based on dielectrophoresis effect. The random lasing modes are changed because of different distribution of polystyrene particles. The mean free path and power Fourier transform of random laser spectra are analyzed to evaluate how the random laser can be controlled by an applied electric field.

並列關鍵字

Random laser ； DNA ； Dielectrophoresis

參考文獻

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