Energy diagram of optical (vertical arrows) and nonradiative (diagonal arrows) transitions in the Si:P laser. Note the terahertz absorption due to transitions from centers into the conduction band.
Concentration of centers (dash) and state population (solid) in Si:P (donor concentration ) as a function of the pump photon flux density (pump intensity) for different compensation (shown in %), (a) in logarithmic scale and (b) in linear scale for the pump intensities between 0 and .
Amplification at for different compensation (shown in %) as a function of pump photon flux density , (a) in logarithmic scale and (b) in linear scale for the pump intensities between 0 and .
Experimental setup. 1, light pipes; 2, shutter to block radiation from the background; 3, silicon sample; 4, sapphire filter; 5, Ge:Ga or detector; , pump radiation from the laser; , spontaneous emission from the Si sample; , path of background radiation when shutter is open; and path of background radiation when shutter is closed.
Temporal behavior of the total signal which includes both spontaneous emission (positive signal) and absorption of background radiation (negative signal) at pump intensity for (a) sample ND5 , (b) sample ND6 , and (c) sample ND7 (, background radiation blocked by a metal shutter).
Spontaneous emission vs pump intensity for the ND5 (solid line) and ND7 (dashed line) samples. The thin dashed line is a linear guide for the eye.
(a) Dependence of the center-induced absorption of background radiation on the pump intensity measured for samples with different compensation (shown in %). (b) Calculated population of centers as a function of pump intensity for samples with different compensation.
Total signal (diamonds), spontaneous emission signal (circles), and absorption (squares) as a function of the pump intensity for the sample ND5 .
Terahertz laser emission for Si:P samples with different compensation (shown in %).
Parameters of the investigated silicon samples.
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