Abstract

We have investigated the intense THz radiation from InAs by applying a strong magnetic field up to 5T. The sample was non-doped bulk InAs with a (100) surface. A mode-locked Ti:sapphire laser was used for an excitation source. A liquid-helium-cooled Si bolometer was provided for detection. We show magnetic field dependence of the THz-radiation intensity in Fig. 1. Solid squares in Fig.1(a) and circles (b) indicate that the magnetic field was applied along 45 and 90 degree to the surface normal, respectively Besides quadratic magnetic field dependence [1,2], we can sec saturation of the THz-radiation. Furthermore, the intensity decreased dramatically above 3T in Fig. 1(a). To obtain more detailed information, we took spectra by a Polarizing Michelson interferometer. In Fig. 2, we show the center frequency at each magnetic field. The spectral shapes for the different magnetic field directions were significantly different. The insets of Fig. 2(a) and (b) are the top view of experimental configuration. In Fig. 2(a) and (b), magnetic field was applied along 90 and 0 degree to the surface normal, respectively While the center frequency in Fig. 2(a) changed dramatically, that in Fig. 2(b) shows almost the same value at each magnetic field. This configuration dependence of the center frequency is attributed to be the initial carrier acceleration processes modulated by a strong magnetic field. We will discuss our analysis about this experiment in detail at the conference.

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