Spectrum control of THz-radiation from InAs under magnetic field by the excitation pulse duration and chirp

Summary form only given. Various THz radiation sources have been intensively studied including photo conductive switches irradiated with ultrashort optical pulses. Zhang et al. (1993) reported quadratic dependence of the laser induced THz-radiation on the magnetic field. Previously, we have reported the significant enhancement of THz-radiation power from InAs under magnetic field irradiated with femtosecond optical pulses. We report the spectrum control of this intense THz-radiation by the width of the excitation pulses and magnetic field. A Ti:sapphire laser delivered 100-fsec pulses for the excitation. The sample was non-doped bulk InAs with a [100] surface. A liquid-helium-cooled InSb bolometer was provided for detection. The InAs sample was placed 45 degrees to the excitation laser beam path. The magnetic field was applied parallel to the sample. In this geometry, the polarization of the THz radiation was horizontal. The THz-radiation power exhibits almost quadratic dependence on the excitation power and higher magnetic field similar to the previous geometry. The spectrum of the THz-radiation was obtained by a polarizing Michelson interferometer.