Generation and Homodyne Detection of Continuous Terahertz Waves Using Single Photoconductive Antenna

The generation and homodyne detection of continuous terahertz (THz) waves using a single photoconductive antenna excited by dual-wavelength continuous-wave laser light have been carried out. The THz waves emitted from the photoconductive antenna are returned and focused onto the same photoconductive antenna via a mirror. Sinusoidal variation of the homodyne current corresponding to the mirror displacement was observed. The homodyne current is caused by THz waves with the frequency of 1028 ±5 GHz. The homodyne current amplitude of 0.5–1.5 nA with a signal-to-noise ratio of 10–25 is obtained with the incident laser power of 4 mW and bias voltage of 10–30 V applied to the photoconductive antenna. The homodyne current amplitude is proportional to the square of the incident laser power up to 2 mW, which can be explained by considering the dependences of the dc photocurrent and dc photoconductance on the irradiating laser power.

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