TEMPERATURE-DEPENDENT 2ND-HARMONIC GENERATION IN TIN PHOSPHORUS SULFIDES

We report the first observation of second harmonic generation in a fer roelectric Sn2P2S6 crystal. It is significant that this crystal system grows in a variety of crystalline phases which can be prepared throug h temperature processing. In particular, we demonstrate a moderately l arge second harmonic signal in two crystalline powders(estimated to be about twenty five times quartz), and show that the intensity exhibits a broad transition showing a polar phase below 90-degrees-C in one fo rm and a temperature-independent polar phase in a second form. When fu rther engineered for absorbance and nonlinearity, this new class of ma terial may show promise in frequency doubler applications.