Fabrication And Parametric Measurement Of K-Na Ion Exchange Glass Planar Waveguides

Among the ion-exchange techniques, K-Na ion-exchange technique is apromising technique in optical communication and sensing, due to its low diffusionvelocity, controllability, good repeatablity, low cost, as well as the high birefringence,low loss and the ease of matching with fiber.There are many reports on buried waveguides, however, unburied waveguides isnecessary for the optical sensing field. The fabricating process of waveguides throughion-exchange technique is easy, but the characterization of them is very complex.Some parameters, such as refractive index profile and transmission loss, are the basisof choosing substrates and the further design and optimization of waveguide devices.The fabrication and characterization of K-Na ion-exchange glass planarwaveguides are introduced in this thesis, as well as a brief history of integrated opticsand ion-exchange technique. The specific contents are shown as following:A. The fabrication of K-Na ion-exchange glass planar waveguides and thedetermination of refractive index profiles of single mode waveguides.IWKB method is a commonly used method in analyzing the refractive indexprofiles of unburied ion-exchange waveguides. However, it is only suitable for thewaveguides that contains more than3modes. For analyzing a single mode waveguide,some will destroy the waveguide, some are very complex, such as multi-wavelengthmethod, beam interference method or matched liquid method.Soda-lime glass planar multimode waveguides were fabricated by K-Naion-exchange technique under380centigrade. Prism coupling method was used tomeasure the effective refractive index. IWKB method was used to analyze therefractive index profiles. The refractive index profiles of TE and TM modes werefitted by Gaussian, exponential and erfc function. The best fitting function is Gaussianfunction. From the refractive index data, the dispersion curve was plotted. From thecurve, the diffusion depth of a single mode was calculated. The diffusion coefficient was calculated from the depth, and the exchange time of a single mode waveguidewas got. Then a single mode waveguide was fabricated. And the refractive indexprofile of a single mode waveguide was got from the dispersion curve, which is asupplement of IWKB method.B. The determination of transmission loss of K-Na ion-exchange glasswaveguideThe transmission loss, depends on the substrate and the fabricating process, is animportant parameter of evaluating the quality and improving the fabricating process.There are some methods for measuring it, such as tail coupling method, F-P method,tri-prism method and so on. Compared with these methods, scattering light method isa easy and convenient method. In this work, the transmission light beam wasphotographed. According to the intensity distribution of the transmission light, thetransmission loss was calculated. This method is ease of measuring and of highaccuracy.