Large-scale polysiloxane ridge multimode optical waveguides applied for inter-chip optical interconnection were designed and fabricated by the soft molding and pattern transferring.Length of the fabricated waveguides was more than 23 cm.The relationship between core residual layer and propagation mode was analyzed by the effective refractive index method.The optical propagation loss of waveguides was 0.14 dB/cm measured by the cutback method and 0.13 dB/cm measured by CCD camera photographing method at 633 ...