Temperature dependent second harmonic generation in tin phosphorus sulfides

We report the first observation of second harmonic generation in a ferroelectric Sn₂P₂S₆ crystal. It is significant that this crystal system grows in a variety of crystalline phases which can be prepared through temperature processing. In particular, we demonstrate a moderately large 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 °C in one form and a temperature-independent polar phase in a second form. When further engineered for absorbance and nonlinearity, this new class of material may show promise in frequency doubler applications.