We report the design and experimental demonstration of electrooptically active TM-guided to TE-radiation mode converters in annealed proton-exchanged (APE) periodically poled lithium niobate (PPLN) channel waveguides in telecom S-C-L bands (1495-1640 nm). A maximum mode conversion efficiency of >95%/cm was obtained at 1520 nm from a 24-mu m-period APE PPLN waveguide under an electro-optic (EO) field of similar to 6.3 V/mu m at 35 degrees C. This efficiency has been enhanced by a factor of >4.6 over a waveguide built in the single-domain (unpoled) LiNbO(3); it is also to the best of our knowledge the most efficient guided-to-radiation (GTR) mode converter ever reported based on LiNbO(3) on-axis waveguides. A conversion bandwidth of similar to 250 nm was also observed from this EO GTR mode converter. (C) 2010 Optical Society of America
