Mode‐conversion type optical Y‐branching waveguides fabricated on glass substrate

Abstract

Y‐branching waveguides for optical splitting and mixing have been proposed and a low loss structure of these devices have been also proposed. We have also proposed a mode conversion type Y‐branching waveguide and the low loss characteristic of this device has been demonstrated by using numerical simulation based on the model of the step‐index type slab optical waveguide. The device structure is based on the structural condition for the multi‐mode coupling system derived from the mode coupling theory. It can be applied to waveguides other than the slab optical waveguide. In this study, it was experimentally investigated whether this method is applicable to the diffused type Y‐branching optical waveguide. In the Y‐branching mode converter formed on a soda‐lime glass, the loss characteristic can be estimated by the mode coupling theory. The loss in this type of device is lower than that in the conventional linear Y‐branching waveguide. It was also confirmed that the low loss structure used in the mode conversion type Y‐branching waveguide is applicable to the diffused channel optical waveguide.