Research on the precipitation of quantum-size particles from Ag_2O-doped glasses

含有量子大小金属粒子的玻璃具有很大的非线性光学磁化率，X^<(3)>，具有超快的nsec - psec速度。他们目前在光通信和光计算领域的光子开关研究处于前沿。本研究致力于制备高含量ag22o掺杂的玻璃衬底，并随后证明通过10-20keV离子能量的离子辐照可以析出量子大小的颗粒。由于化学耐久性好，易掺杂Ag离子，选择了P_2O_5-Al_2O_3-Ag_2O（Ag_2O=10-20 mol %）作为玻璃衬底材料。较低能量的N_2^+、Ar^+等离子辐照可以在玻璃表面附近析出高浓度的量子大小的Ag粒子。利用FE-SEM和420 nm处等离子体吸收峰的强度和形状数据直接估算了它们的尺寸。为了测量X^<(3)>值，Ag粒子浓度应该增加。因此，寻找合适的玻璃成分：成功找到了P_2O_5-Al_2O_3-Ag_2O (15-20mol %) -Na_2O （15-20mol %）玻璃，其浓度是非na_2o玻璃的两倍。在450nm波长下，用短脉冲激光简并四波混频（DFWM）计算得到样品的X^<(3)>为5.5 ~ 8.8*10^<-7 >esu。该技术对颗粒大小的精确控制正在进行中。

Glasses containing quantum-size metal particles can exibit a large nonlinear optical susceptibility, X^<(3)>, with ultra fast speed of nsec - psec. They are currently at the forefront reseaech for photonic switches in optical communication and optical computing. This research has been dedicated to prepare high-content Ag_2O-doped glass substrates and subsequently demonstrate precipitation of quantum-size particles by ion irradiation of 10-20keV ion energy.Because of good chemical durability and easy Ag ion doping, P_2O_5-Al_2O_3-Ag_2O(Ag_2O=10-20 mol %) were chosen as glass substrate materials. Ion irradiation such as N_2^+, Ar^+ with relatively low energy can precipitate high concentration of the quantum-sized Ag particles near the glass surface. Their sizes were estimated directly by FE-SEM,and from the data of the intensity and shape of the plasma absorption peak at the wavelength of 420 nm.To measure the X^<(3)> value, the Ag particle concentration should increase. Thus, appropriate glass composition was searched : P_2O_5-Al_2O_3-Ag_2O (15-20mol %) -Na_2O (15-20mol %) glasses were successfully found and resulted in the two times concentration as large as that of non-Na_2O glasses. At 450 nm wavelength, by degenerate four-wave mixing (DFWM) with a short pulsu laser, X^<(3)> of 5.5-8.8*10^<-7> esu was estimated from these samples. Precise control of particle size by the technique is in progress.