A compact THz-radiation source consisting of a bulk semiconductor, a mode-locked fiber laser, and a 2-T permanent magnet

Various THz-radiation sources have been intensively studied in the past, including photoconductive switches irradiated with ultrashort optical pulses. The average power of optical short-pulse excited THz radiation sources was at the microwatt level, mostly limited by the electric break-down of the photoconductive antennas. An intense, compact, and simple light source is required for applications in sensing or imaging. Zhang et al. (1993) reported on a compact THz-radiation source consisting of a biased photoconductive antenna and a mode-locked fiber laser as an excitation source. They also reported the quadratic dependence of laser induced THz-radiation on the magnetic field. We have also demonstrated strong enhancement of THz-radiation power with a magnetic field with the use of an InAs semiconductor instead of GaAs. The advantage of the magnetic field enhancement scheme is flexibility of the geometry and easier scalability of the system. In the presentation, we report on a compact THz-radiation source consisting of a fiber femtosecond laser and a 2-T newly-designed permanent magnet.