Abstract

In recent years, considerable effort has been dedicated to the search for non-linear optical crystals suitable for second harmonic generation (SHG) of semiconductor diode lasers. So far, there have been a number of reports of diode pumped phase matched SHG based on potassium niobate (KNbO₃) [1] and pseudo-phase matched SHG of periodic domain inverted lithium niobate (LiNbO₃) [2]. However, both these materials have disadvantages. Periodically poled LiNbO₃ is difficult and expensive to produce and may not be suitable for high power applications. KNbO₃ has a small phase matched temperature bandwidth (~0.5°C) and exhibits phase transitions at ~ -40°C (mm2 → m3) and ~ 210°C (4mm → mm2). In consequence, the crystals may be converted to multi-domain structure by simple mechanical shock or at temperatures over 40°C [3].

© 1996 IEEE