Fabrication And Measurement Of Ion-exchange Waveguides Based On Glass Films

Optical waveguides are the base of the integrated optical circuits. They are the carriers for rapidly transmitting optical signals in large quantities. All devices are connected with waveguides and fibers in optical systems. As the elements for restricting and guiding the light, their essential is that the refractive index of waveguides is higher than that of external medium. Ion-exchange waveguiding components based on glass has its special advantages, such as low loss, good maching with single-mode optical waveguide and low cost. Due to these superiorities, it has unparalleled importance, practical and commercial value in the integrated optics, also it is promising for optical communications. But the conventional ion-exchange waveguiding components based on glass need fine edge polishing, the combination of thin-film technology and ion-exchange method in this paper, not only can eliminate the edge polishing, but also can achieve the integration of the mature silicon-based thin film active and passive device, which is very mature in present. In this paper, firstly, the BK7 glass thin film with a few micrimeter thickness was deposited on silica substrate by radio-frequency magnetron sputtering method, then a 150 nm Al film was deposited on the glass film, and the photolithograph technique is used to form an open window on Al film. Lastly, the ion-exchange was carried out in lg AgNO3,3.8g NaNO3 and 15.2g KNO3 eutectic salt melt at 340℃for 20 min. After ion-exchange, Al film was corrupted and removed. Then a channel waveguide was fabricated successfully. Under certain conditions, the light can achieve total reflection in the waveguide.Waveguide refractive index profile is an important feature of optical waveguide. By making use of the prism-coupling principle and improved inverse WKB theory, it can realize the refractive-index profile determination of the ion-exchange waveguide based on BK7 glass thin film.In addition, we analysis the waveguiding transmission spot through the near-filed pattern method using the fiber-waveguide alignment and end coupling technology. On the basis of this system, we have measured the loss of ion-exchange waveguide based on BK7 glass film through adding two identical 3dB couplers at both end-side of the waveguide.