Mode-order converter in a multimode waveguide

A novel device that converts the order of modes in an integrated-optic multimode waveguide was proposed and fabricated. The device consists of two mode splitters and tapered waveguides. Its operation at a wavelength of 1.55 microm was confirmed by observation of the output mode profiles. The cross talk measured by an indirect method was >10.2 dB. The excess loss with reference to a straight multimode waveguide was 1.5 dB, compared with the propagation loss of a straight multimode waveguide.