مرکز منطقه ای اطلاع رساني علوم و فناوري - Channel waveguides in glass via silver-sodium field-assisted ion exchange

Abstract :

Multimode channel waveguides were formed by field-assisted diffusion of Ag+ ion from vacuum-evaporated Ag films, into a sodium aluminosilicate glass reported to yield high diffusion rates for alkali ions. Two-dimensional index profiles of channel waveguides formed by diffusion from a strip aperture were controlled by means of diffusion time, temperature, and electric field. The diffusion equation for diffusion through a strip aperture in the presence of a one-dimensional electric field was solved. Its solution was in agreement with measured concentration profiles: $frac{C(x,y,t)}{C_{0}} = frac{1}{2} { erf (frac{a - x}{2\\sqrt {Dt}}) + erf (frac{a + x}{2\\sqrt {Dt}})}$ $\\cdot \\frac{1}{2} \\Bigg\\{ \\hbox{ erfc } \\bigg( \\frac{y - \\mu E_{y}t}{2\\sqrt{Dt}} \\bigg) + e^{(yE_{y}/D)} \\hbox{ erfc } \\bigg( \\frac{y + \\mu E_{y}t}{2\\sqrt{Dt}} \\bigg) \\Bigg\\}$ Diffusion coefficients in this aluminosilicate glass were determined to be $D =(2.41 \\times 10^{-13}) (frac{m^{2}}{s}))$ $.\\exp (frac{-3.1 \\times 10^{4}frac{J}{mol}}{RT})$ Diffusion coefficients were higher (between 150°C and 300°C) than those of a low-iron soda-lime silicate glass "standard" also studied, for which diffusion coefficients were $D =(3.28 \\times 10^{-13} (frac{m^{2}}{s}))$ $.\\exp (frac{-3.6 \\times 10^{4}}{RT} (frac{J}{mol}))$ This difference in diffusion coefficients is due to the higher activation energy of diffusion in the soda-lime silicate glass. The Gladstone-Dale relation was used to calculate the maximum possible refractive index change via Ag+-Na+ ion-exchange for each type of glass. The maximum index change in the sodium aluminosilicate glass is found to be about 65 percent of that in the soda-lime silicate glass.