Transient-type stimulated emission in the terahertz (THz) frequency range has been achieved from phosphorus doped silicon crystals under optical excitation by a few-picosecond-long pulses generated by the infrared free electron lasers FELIX and CLIO. The analysis of the lasing threshold and emission spectra indicates that the stimulated emission occurs due to combined population inversion based lasing and stimulated Raman scattering. Giant gain has been obtained in the optically pumped silicon due to large THz cross sections of intracenter impurity transitions and resonant intracenter electronic scattering. The transient-type emission is formed under conditions when the pump pulse intervals exceed significantly the photon lifetime in the laser resonator.

中文翻译：

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掺杂硅的太赫兹瞬变激发发射

在红外激发下，红外自由电子激光器FELIX和CLIO产生了几皮秒长的脉冲，从掺磷的硅晶体在光激发下获得了太赫兹（THz）频率范围内的瞬态激发光。激光阈值和发射光谱的分析表明，受激发射的发生是由于基于人口反转的激射和受激拉曼散射相结合。由于中心内杂质跃迁的THz大截面和中心内共振电子散射，在光抽运的硅中获得了巨大的增益。瞬态发射是在泵浦脉冲间隔大大超过激光谐振器中的光子寿命的条件下形成的。