Abstract

Short wavelength coherent light sources are required for applications such as process monitors and fluorescence based instruments. QPM waveguides can be used to frequency double GaAlAs diode laser output for this purpose. However the efficiency of chemically poled waveguides of different ferroelectric crystals such as LiNbC₃, LiTaO₃ and KTiOPO₄ degrade as the generated wavelength approaches the UV spectral range. The degradation is characterized by a decrease in the peak doubling efficiency, broadening of the QPM curve and reduction in the IR transmissivity of the waveguide. The damage increases with the intensity of the SH wave, limiting the power which can be generated by these waveguides. There is limited information in the literature on the degradation mechanism. The presence of the two waves in the waveguides and the strong variation of the SH power along the waveguide give rise to complex dependence of the output power with time, input IR power and wavelength that is difficult to characterize with SHG measurements alone.

© 1996 Optical Society of America