Design and analysis of wide-angle Y-branch waveguide with low losses for integrated optics

A new wide-angle, low-loss, symmetrical Y-branch waveguide is proposed. The waveguide configuration utilizes ribs for lateral confinement in the planar guiding region underneath. This Y-branch structure can be fabricated easily without any additional processes. Together with multi-mode interference effect, a local decrease of the waveguide ridge in a wedge at the Y-branch region reduces the radiation loss. When properly designed, the proposed Y-branch has a radiation loss as low as 2.2 dB at a branch angle of 6 degrees with index difference ((Delta) n/n) as small as 7.1 multiplied by 10 -4 at a wavelength of 870 nm in the TE fundamental mode.