Laser radiation in active amplifying media treated as a transport problem : transfer equation derived and exactly solved

• Published in: Astrophysics and space science Vol. 184; no. 1; pp. 77 - 142
• Main Authors: SANTANU DAS GUPTA, DAS GUPTA, S. R
• Format: Journal Article
• Language: English
• Published: Dordrecht Kluwer 01.10.1991
• Subjects: Doped-insulator lasers and other solid state lasers; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lasers; Optics; Physics; Bar; Radiative transfer; Transport; Laser; Rate equation; Solid state laser
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/BF00644869

The flow of laser radiation in a plane-parallel cylindrical slab of active amplifying medium with axial symmetry is treated as a problem in radiative transfer. The appropriate one-dimensional transfer equation describing the transfer of laser radiation has been derived by an appeal to Einstein's A, B coefficients (describing the processes of stimulated line absorption, spontaneous line emission, and stimulated line emission sustained by population inversion in the medium) and considering the 'rate equations' to completely establish the rational of the transfer equation obtained. The equation is then exactly solved and the angular distribution of the emergent laser beam intensity is obtained; its numerically computed values are given in tables and plotted in graphs showing the nature of peaks of the emerging laser beam intensity about the axis of the laser cylinder. (Author)