Planar, buried, ion-exchanged glass waveguides: Diffusion characteristics
Planar, buried, ion-exchanged glass waveguides: Diffusion characteristics
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平面埋入式离子交换玻璃波导：扩散特性
DOI：
10.1109/jqe.1986.1073050
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发表时间：
1986
影响因子：
2.5
通讯作者：
S. Najafi
中科院分区：
文献类型：
--
作者：
R. Ramaswamy;S. Najafi
A detailed theoretical and experimental study of Ag+-Na+ exchange in soda-lime silicate glasses in a molten bath containing a mixture of NaNO 3 and Ag+ is presented. With no applied field, concentration profiles C(x, t) (and therefore, the index profiles for low concentrations) are given by complementary error function. The estimated value for the self-diffusion coefficient D of Ag+ is 0.133 μm2/min for low concentrations and it monotonically increases with the surface concentration C 0 until it saturates at about 0.3 μm2/min for C_{0} \geq 10^{-3} MF. However, square root dependence of diffusion depth with time seems to be independent of the C 0 . Presence of an external field E causes the effective depth of diffusion to increase. In fact, for large E fields, the profile can accurately be described by C/C_{0} = \frac{1}{2} erfc(x' - r) where r = \mu Et/\sqrt{2Dt} where μ is the ionic mobility of Ag+in glass. We define a new diffusion depth W as the distance from the surface to the 1/e concentration point, and for large fields, W varies linearly with E and t . Experimental results yielded a value of 15.55 μm2/ V min forμ. As before, square root dependence of W with t and the linear variation of W versus C 0 for C_{0} \leq 10^{-3} MF, with W saturating for C_{0} > 10^{-3} MF, were observed in the case of field assisted diffusion. A two-step process, where a surface waveguide formed in the first step with either E equal to zero or some finite value, is modified by performing a second diffusion in pure sodium nitrate to produce a buried, symmetrical fiber-like profile. This process is also studied in detail.
A detailed theoretical and experimental study of Ag+-Na+ exchange in soda-lime silicate glasses in a molten bath containing a mixture of NaNO 3 and Ag+ is presented. With no applied field, concentration profiles C(x, t) (and therefore, the index profiles for low concentrations) are given by complementary error function. The estimated value for the self-diffusion coefficient D of Ag+ is 0.133 μm2/min for low concentrations and it monotonically increases with the surface concentration C 0 until it saturates at about 0.3 μm2/min for C_{0} \geq 10^{-3} MF. However, square root dependence of diffusion depth with time seems to be independent of the C 0 . Presence of an external field E causes the effective depth of diffusion to increase. In fact, for large E fields, the profile can accurately be described by C/C_{0} = \frac{1}{2} erfc(x' - r) where r = \mu Et/\sqrt{2Dt} where μ is the ionic mobility of Ag+in glass. We define a new diffusion depth W as the distance from the surface to the 1/e concentration point, and for large fields, W varies linearly with E and t . Experimental results yielded a value of 15.55 μm2/ V min forμ. As before, square root dependence of W with t and the linear variation of W versus C 0 for C_{0} \leq 10^{-3} MF, with W saturating for C_{0} > 10^{-3} MF, were observed in the case of field assisted diffusion. A two-step process, where a surface waveguide formed in the first step with either E equal to zero or some finite value, is modified by performing a second diffusion in pure sodium nitrate to produce a buried, symmetrical fiber-like profile. This process is also studied in detail.