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Author: Zhukavin, R.K. × Type: Article ×

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    Terahertz stimulated emission from silicon doped by hydrogenlike acceptors
    (College Park : American Institute of Physics Inc., 2014) Pavlov, S.G.; Deßmann, N.; Shastin, V.N.; Zhukavin, R.K.; Redlich, B.; van der Meer, A.F.G.; Mittendorff, M.; Winnerl, S.; Abrosimov, N.V.; Riemann, H.; Hübers, H.-W.
    Stimulated emission in the terahertz frequency range has been realized from boron acceptor centers in silicon. Population inversion is achieved at resonant optical excitation on the 1Λ8+ → 1Λ7- , 1Λ6-, 1Λ8- intracenter transitions with a midinfrared free-electron laser. Lasing occurs on two intracenter transitions around 1.75 THz. The upper laser levels are the 1Λ7- , 1Λ6- , and 1Λ8- states, and the lower laser level for both emission lines is the 2Λ8+ state. In contrast to n-type intracenter silicon lasers, boron-doped silicon lasers do not involve the excited states with the longest lifetimes. Instead, the absorption cross section for the pump radiation is the dominating factor. The four-level lasing scheme implies that the deepest even-parity boron state is the 2Λ8+ state and not the 1Λ7+ split-off ground state, as indicated by other experiments. This is confirmed by infrared absorption spectroscopy of Si:B.
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    Terahertz emission from lithium doped silicon under continuous wave interband optical excitation
    (Bristol : IOP Publ., 2015) Andrianov, A.V.; Zakhar'in, A.O.; Zhukavin, R.K.; Shastin, V.N.; Abrosimov, N.V.
    We report on experimental observation and study of terahertz emission from lithium doped silicon crystals under continuous wave band-to-band optical excitation. It is shown that radiative transitions of electrons from 2P excited states of lithium donor to the 1S(A1) donor ground state prevail in the emission spectrum. The terahertz emission occurs due to capture of nonequilibrium electrons to charged donors, which in turn are generated in the crystal as a result of impurity assisted electron-hole recombination. Besides the intracentre radiative transitions the terahertz emission spectrum exhibits also features at about 12.7 and 15.27 meV, which could be related to intraexciton transitions and transitions from the continuum to the free exciton ground state.
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    Terahertz transient stimulated emission from doped silicon
    (Melville, NY : AIP Publishing, 2020) Pavlov, S.G.; Deßmann, N.; Pohl, A.; Zhukavin, R.K.; Klaassen, T.O.; Abrosimov, N.V.; Riemann, H.; Redlich, B.; Van Der Meer, A.F.G.; Ortega, J.-M.; Prazeres, R.; Orlova, E.E.; Muraviev, A.V.; Shastin, V.N.; Hübers, H.-W.
    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. © 2020 Author(s).