Femtosecond Laser Micromachining of Cladding Waveguides in KTiOAsO4 Crystal for Second‐Harmonic Generation

Second‐harmonic generation (SHG) of green lasers generated in KTiOAsO 4 (KTA) cladding waveguides fabricated by femtosecond laser direct writing (FsLDW) is reported. The minimum propagation loss of the fabricated waveguides is determined to be 2.39 ± 0.24 dB cm −1 at 1064 nm. The SHG performance is characterized by utilizing a 1064 nm pulsed laser. The maximum SHG conversion efficiency reaches 13.67%. This work suggests potential applications of KTA crystals and FsLDW technology in definition of compact waveguide devices for integrated nonlinear optics.