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Intracavity third-harmonic generation in Si:B pumped by intense terahertz pulses
We observe third-harmonic generation (THG) in boron-doped silicon (Si:B) upon pumping with picosecond 1.56 THz pulses from a free-electon laser with a peak electric field strength of up to 12 kV/cm. The measurements are performed at cryogenic temperatures where the majority of holes are bound to the acceptor dopants. The dependence of the THG on the pump intensity exhibits a threshold-free power-law behavior with an exponent close to 4. The observations can be explained by THz emission by free holes accelerated in the non-parabolic valence band, under the assumption that the density of free holes increases with the pump intensity. A quantitative treatment supports that these carriers are generated by impact ionization, initiated by the population of thermally ionized carriers , as opposed to direct tunneling ionization. In addition, we also observe intracavity THG by embedding the Si:B in a one-dimensional photonic crystal cavity. The THG efficiency is increased by a factor of eight due to the field enhancement in the cavity, with the potential to reach a factor of more than 100 for pump pulses with a spectrum narrower than the linewidth of the cavity resonance.
- Intracavity third-harmonic generation in Si:B pumped by … (Id 31496) HZDR-primary research data are used by this (Id 31450) publication
Physical Review B 102(2020), 075205
- Original PDF 985 kB Secondary publication