Compact and stable blue lasers based on KNbO/sub 3/

Summary form only given. Direct frequency upconversion of near-infrared semiconductor diode lasers (DLs) is a promising route to robust, compact, and reliable blue lasers. KNbO/sub 3/ is very attractive for frequency conversion of near-infrared DLs into the blue spectral range due to its high nonlinear optical coefficients, its favorable phase-matching configurations, and the absence of any optical damage and gray tracking effects for cw blue power levels of up to at least 200 mW. Recently, we successfully fabricated ridge waveguides in KNbO/sub 3/ by combining ion implantation and ion sputtering. Up to 14 mW of blue light at a wavelength of 438 nm was generated. No decrease in blue power was observed during a test period of 10 h, indicating the absence of optical damage or degradation of the waveguide performance. The development of prototype blue lasers is in progress, and devices emitting several tens of milliwatts have already been demonstrated in our laboratory. We will report recent results on single-pass blue-light second-harmonic and sum-frequency generation in KNbO/sub 3/ crystals and waveguides.