New type low-loss SiO2Y-branch waveguide

A novel Y-branch waveguide structure, in which a transitional guide is embedded between an incident channel and output branches, is presented. The transitional guide is used to improve the mode field matching between both waves supported by the incident and output waveguides. Numerical simulations show that this geometry can minimize the junction loss to 0.041dB at 1310nm and 0.052 dB at 1550nm wavelength, respectively. Silica samples based on the design are fabricated by PECVD. Determination shows that the samples exhibit very low junction loss of about 0.08 dB and 0.09 dB at the two wavelengths.