Producibility of the ion-exchange method in manufacturing gradient refractive index in glass

Abstract

Abstract. This paper presents the technological aspect of application of the ion exchange method in producing gradient refractive index in glass. The possibility of predictable and repeatable producing of the changes in glass refraction with the use of this method has been presented, as well as the method of in situ control of the process of diffusion doping of glass based on the measurement of the temperature. This method is based on simultaneous (to the carried process) solving the nonlinear diffusion equation modeling the spatio-temporal changes in normalized concentration of the admixture ions in glass. For this purpose the knowledge of temperature characteristics of diffusion coefficients of exchanged ions is used. The result of such control of diffusion processes is information on the current (temporary) refractive index profile of the resulting waveguide. The presented method of control has been confirmed by experimental results, which concern modeling and measurements of planar waveguide structures of slab type. The proposed methodology can also be used to control the diffusion processes of producing another type of two-and three-dimensional gradient structures. According to the author's knowledge the method mentioned above has not been described in literature before.

Stresses Produced in the BK7 Glass by the K+–Na+ Ion Exchange: Real-Time Process Control Method

“…A prismatic coupler made of PSK-3 glass (from Schott AG, Mainz, Germany) was used (refractive index n 677 = 1.5491, breaking angle δ = 70.0963 • ). The uncertainties of the determined effective refractive indexes of the waveguide modes were of the order of~10 -4 [15]. The refractive index profiles were calculated using a procedure based on the mode characteristic equation [14,19].…”

“…Solving this equation is carried out in parallel with the implementation of the diffusion process. The temperature in the crucible is measured at specific According to the scheme shown in Figure 3, the diffusion equation is integrated here in the time domain with the ∆t time step [14,15]. Solving this equation is carried out in parallel with the implementation of the diffusion process.…”

“…By adjusting the solution of the diffusion equation to each of the designated in that way n 0 (x) profiles, the temperature dependencies of diffusion coefficients of the exchanged ions were determined [14]. Using the linearized form of the Arrhenius equation, the values of coefficients describing D 0A (T) and D 0B (T) temperature dependencies [15] were determined. An illustration of these dependencies is shown in Figure 5.…”

“…The paper presents the use of this method for determining the function of stress distribution generated by K + ↔Na + ion exchange in BK7 glass. A method of monitoring the occurring stresses (resulting from the ion exchange, based on the determination of diffusion profiles of dopant ions introduced into the glass) in the real time of the process [15] is also presented. The results obtained from the monitoring were compared with the results of optical measurements.…”

Producing the Gradient Changes in Glass Refraction by the Ion Exchange Method — Selected Aspects

“…where k 0 -wave number of an electromagnetic wave in a free space, Figure 19 schematically shows the principle of control of diffusion processes described earlier [46].…”