Abstract
Second harmonic generation (SHG) was observed from halide, in particular, chlorine-containing glasses. The magnitude of SHG increased with increasing ZnCl2 concentration and poling time. Although the mechanism of SHG is still controversial, the deficiency of cations near the anode surface was detected. However, in this glass system, the polishing of the anode side showed no effect on SHG. However, the polishing of the cathode side significantly decreased the magnitude of SHG. Therefore, the SHG mechanism in this glass system is made evident for the first time in which the movement of anions resulting in an anion-deficient layer near the cathode side is able to cause SHG.