Second harmonic modulation in potassium niobate

Abstract We consider potassium niobate as a medium for room‐temperature second‐harmonic generation at 430 nm and electro‐optic modulation in a single crystal. Modulation voltages of the order of 60 V are needed to fully switch the second harmonic for an electric field applied along the crystal c axis and modulation frequencies in the megahertz range. Although the electro‐optic coefficient for a field applied along the crystal b axis is 10 times larger than for the c‐axis modulation, the voltage required is three times higher. A laser‐diode‐pumped source of high‐frequency intensity‐modulated blue laser light may find application for undersea communication.