Periodically segmented waveguides were fabricated by the ion exchange process in KTiOPO4. The waveguides were characterized by measuring the spectra of the transmitted and reflected guided infrared light and of the second‐harmonic‐generated power. The near‐field distribution of the fundamental and second‐harmonic wave was also investigated. Infrared to blue light conversion efficiency up to 250% W−1 cm−2was obtained. Waveguide characteristics were calculated by replacing the segmented structure with an equivalent continuous waveguide. Good agreement between the calculated and measured values was obtained.