摘要 我們利用時間解析散射光量測、氦氖雷射激發-白光探測(He-Ne Laser pump and White light Probe,簡稱激發探測)實驗以及開孔Z-scan技術,研究AgOx近場超解析結構受光照射後的線性與非線性光學性質變化。 時間解析散射光量測發現。在激發探測實驗中發現AgOx近場超解析結構受光照射過程中,起初表面的散射光強度隨照光時間增加而增強,隨後呈現飽和現象。在激發探測實驗中的白光穿透頻譜中,我們發現隨樣品厚度增加其縱模共振波長的紅移現象,此外也觀察到樣品受光照射前後的穿透頻譜的細微變化---橫模共振吸收減弱。而開孔Z-scan的量測結果顯現隨實驗雷射功率增強其Z-scan曲線由反飽和吸收特徵漸漸的轉為飽和吸收特徵。 根據時間解析散射光量測與激發激發實驗結果,我們做出以下推論,AgOx近場超解析結構中的AgOx膜層是由AgO、Ag2O以及Ag構成之Ag-rich奈米複合物系統;氧化銀熱解析出之銀原子不會自行凝聚成銀顆粒,而是被吸附在AgOx膜層中既有的銀顆粒上,導致AgOx膜層中原已存在之銀顆粒,在形狀上變得較為對稱、尺寸上些微變大;而導致散射光強度的增強,導因於熱分解析出之氧分子則造成AgOx近場超解析結構中的保護層形貌扭曲。 在開孔Z-scan技術的部分,我們提出雙成份模型(Bi-composition model),成功的從複雜的開孔Z-scan曲線中分析出AgOx近場超解析結構的非線性光學特性,並且求得βAg 為 -2.27 ╳ 103(cm/GW)以及βAgOx為1.81 ╳ 106(cm/GW)。
Abstract In this thesis, we use time-dependent light scattering experiment, pump-probe experiment, and femtosecond laser Z-scan measurement to study the linear and nonlinear optical properties of AgOx nano thin film under laser irradiation. In the time-dependent light scattering exp., we observe the protection layer of the super-RENS sample is distorted by the thermal dissociated oxygen molecule and the intensity of scattering light is increased with the irradiation time. Two corollaries is proposed in the pump-probe exp. First, AgOx nano thin film is mixture of AgO, Ag2O and Ag. Second thermal dissociated Ag atom will adsorbed on intrinsic Ag cluster and result in the slight change of the size and shape of the Ag clusters. In the femtosecond laser Z-scan measurement , it is found that the OA Z-scan curve slowly converts from a dip feature to a peak feature when the scanning laser intensity increases. A bi-composition model is proposed to explain this complex nonlinear optical response. The nonlinear optical absorption coefficient of Ag and silver oxide nanoparticle are determined βAg =-2.27 ╳ 103 cm/GW and βAgOx=1.81 ╳ 106 cm/GW at λ=800nm respectively.