TunableGrain Orientation of Chalcogenide Film andIts Application for Second Harmonic Generation

To date, second harmonic generation (SHG) plays a vital role in photonic devices. However, it is a formidable challenge to achieve reconfigurable SHG. Hereby, we experimentally demonstrate the SHG response from the oriented Ge2Sb2Te5 (GST) grains induced by polarized laser pulses for the first time. The orientation of GST grains is found to be perpendicular to the polarization direction of the pump laser. Such unique ordered structures result in a periodic change of SHG intensity with the input polarization angle of the pump laser rotating every 180 degrees. These findings may pave avenues for generating nonlinear optical source with a simple process, scalability and switchable functionality.