Laser-driven spontaneous emission. Calculation by fourth order approximation

Benjamin Fain, S. H. Lin

Daniel F. Walls, Crispin W. Gardiner

Benjamin Fain

The intensity of radiation, stimulated by laser pulses of arbitrary shape, is derived up to fourth-order terms. It is shown that there is a linear fourth-order mechanism of emission that depends on linear susceptibilities of molecules. This linear mechanism reveals collective, super-radiant features. The intensity of laser-driven spontaneous emission (LDSE) is proportional to for samples smaller than , where is a wavelength of emitted radiation, and N is the number of molecules. For extended volumes , the intensity of LDSE is proportional to . Equations of motion describing collective radiation damping are derived.

Stig Stenholm

Benjamin Fain

The intensity of radiation stimulated by laser pulses of arbitrary shape is derived up to the fourth order terms. It is shown that there is a linear fourth order mechanism of emission that depends on linear susceptibilities of molecules. This linear mechanism reveals collective, superradiant features. The intensity of laser-driven spontaneous emission (LDSE) is proportional to N2 for samples smaller than (lambda) 3, where (lambda) is a wavelength of emitted radiation, and N is the number of molecules. For extended volumes >> (lambda) 3, the intensity of LDSE is proportional to N4/3. Equations of motion describing collective radiation damping are derived.

Benjamin Fain

The intensity of spontaneous emission by atoms or molecules in a stationary state in contact with a thermal bath at temperature T, is derived up to the fourth-order approximation in electronic charge. The perturbative treatment of the intensity of the stationary spontaneous emission is shown to be valid only if the relaxation rate is much larger than w, the rate of spontaneous emission. A specific model gives the stationary spontaneous emission intensity for all values of and w.