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Raman-type emission spectra of a Si:P laser obtained at maximum pump power. The vertical axis shows the pump photon energy (baseline of each emission spectrum). The intensity is plotted linearly. The lower inset shows a sketch of the experimental setup. The upper inset shows the scheme of the Raman laser process: pumping occurs from the ground state into a virtual state (dashed line). An excited electron decays in the donor state with the emission of a terahertz photon and finally relaxes nonradiatively by emission of an intervalley -TA phonon.
Dependences of the emission intensity (a) and emission photon energy (b) on the pump photon energy. The arrows in (a) as well as the vertical lines in (b) indicate the positions of the photon energies which correspond to resonant pumping in excited donor states. The filled symbols in (b) indicate strong lines and the open cycles are for the weak ones. Diamonds show the lines corresponding to the Stokes shifted Raman emission. The solid line in (b) shows the linear fit for the frequency shift of the Stokes emission. The horizontal dashed lines in (b) indicate the Si:P donor laser transition. Labels I to V indicate pump energy for the Raman emission lines.
Typical dependences of the terahertz emission from Si:P on the pump photon flux density.
Emission spectra and corresponding emission pulses (insets) recorded for the case of resonant pumping into the state (line I in Figs. 2 and 3). The spectra are taken with different time gates shown by the rectangles in the insets. The labels in dB indicate the attenuation of the pump power; corresponds to .
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