Strong enhancement of THz radiation from InAs surfaces under magnetic fields at low temperatures

THz radiation has been observed from various semiconductor surfaces by exciting with femtosecond laser pulses. We report the magnetic field and temperature conditions for the strongest THz radiation from the [111] InAs surface up to 5 T and down to 10 K. We also measured the spectral intensity of the THz radiation by inserting a Martin-Puplett type interferometer between the magnet and the bolometer. We found that the relative intensity of the higher frequency spectral components increases at high magnetic fields. This result may be explained by the increased acceleration of the electrons in the higher magnetic fields.