Abstract

Direct second-harmonic and sum-frequency generation (SHG, SFG) with near infrared semiconductor laser diodes (LDs) offers the possibility of robust, compact and reliable blue lasers. KNbO₃ crystals are very attractive for frequency conversion of near infrared DLs into the blue spectral range due to its high nonlinear optical coefficients, its favourable noncritical phase-matching (PM) configurations, and the absence of any optical damage and gray tracking effects for cw blue power levels of up to 200 mW¹. Efficient blue light generation at 430 nm and 490 nm by noncritical type I PM SHG with LDs in KNbO₃ has been reported for single-pass^2,3, resonant^4,5, and waveguide configurations⁶. Other wavelengths in the 415 to 475 nm spectral range can be efficiently generated by making use of the nonlinear optical coefficient d₃₂ of KNbO₃ for noncritical type I PM SFG with commercially available single-mode AlGalnP, AlGaAs and InGaAs laser diodes.

© 1996 IEEE