Fabrication and characterisation of periodically poled lithium niobate waveguide using femtosecond laser pulses

We present in this letter the fabrication and characterization of thermally stable type II waveguides in Z-cut periodically poled lithium niobate crystals. The waveguides were fabricated by using a femtosecond laser and were utilized for second harmonic generation. Our experiments have shown that a quasiphase matching wavelength of 1548.2nm, a tuning bandwidth of 2nm, and a tuning temperature range of 150.4±1.6°C can be achieved.