Periodically segmented waveguides made by ion-exchange in glass: application to a TE-pass polarizer and to an asymmetric Y-junction wavelength demultiplexer

Abstract

In this paper, the realization and characterization of periodic segmented waveguides made by ion-exchange on glass is presented as well as their application to polarizers and wavelength duplexers. Segmented waveguides are of major interest for integrated devices because they allow tailoring the refractive index without changing the technological parameters. Indeed, a segmented waveguide, which is composed of a periodic succession of guiding and non-guiding zones, can be considered as a classical waveguide with a core refractive index that ranges from the segmented core to the substrate ones, depending on the segmentation ratio. Through this way, it is thus possible to avoid the use of more complex techniques that require a double-step lithography process. In the first part of the article, surface segmented waveguides made by ion-exchange on glass are studied and a linear relationship between the segmentation duty cycle and the maximum core refractive index of an equivalent continous waveguide is demonstrated. A simple correction on the duty cycle is needed to take into account the longitudinal diffusion. After a presentation of its principle of operation, in the second part of the article, we propose the realization and characterization by means of segmented waveguide of a polarizer with more than 30dB of extinction ratio at λ=1550nm. Finally, the design and first results obtained on a duplexer based on an asymmetric segmented Y-junction are presented.