Second harmonic generation in femtosecond laser written lithium niobate waveguides based on birefringent phase matching

Abstract

We report on second harmonic generation (SHG) through birefringent phase matching in femtosecond (fs) laser fabricated lithium niobate (LiNbO3) waveguides. Based on end-face coupling system, the guiding properties (mode profiles and propagation losses) of these waveguides are studied at 1064 nm. The effects of guiding properties on SHG of 1064 nm are investigated in detail. The maximum conversion efficiency of 0.87% is acquired in a 10-mm-long depressed-cladding waveguide at room temperature. Our results pave a way for constructing novel frequency converters based on fs-laser written LiNbO3 waveguides.