Continuous wave terahertz generation up to 2 THz by photomixing on ion-irradiated In0.53Ga0.47As at 1.55 μm wavelengths

We report the generation of continuous terahertz waves from microwave frequencies of up to 2 THz obtained by photomixing two optical waves at 1.55 μm wavelengths in ion-irradiated In0.53Ga0.47As interdigitated photomixers. A 200 nm thick silicon nitride coating is used for antireflection and passivation layer, improving the reliability and the heat tolerance of the photomixer. In such devices, output powers greater than 40 nW at 0.5 THz and 10 nW at 1 THz have been achieved. Considering the observed saturation of the output power with the increase of bias voltage, the optimum excitation conditions regarding optical power and bias voltage are discussed