A quantum theory is developed for the spontaneous optical parametric process in nonlinear, anisotropic, and dispersive media; the process is treated directly as a scattering problem rather than a problem involving equivalent coupled oscillators. Following the general procedure in quantum field theory, a general expression is obtained for the differential extinction coefficient, which contains all the information on the intensity of the spontaneous emission in the parametric scattering process. The tuning characteristics, beam divergence, and spectral properties of the spontaneous emission for colinear and noncolinear interactions are described in detail and illustrated with numerical examples on such standard nonlinear optical crystals as LiNb ${\mathrm{O}}_{3}$ , N ${\mathrm{H}}_{4}$ ${\mathrm{H}}_{2}$ P ${\mathrm{O}}_{4}$ , and K ${\mathrm{H}}_{2}$ P ${\mathrm{O}}_{4}$ under various pumping conditions. Explicit formulas for the intensity of the spontaneous emission are also obtained. The spontaneous intensity calculated using the formulas given is shown to be in complete agreement with known experimental data on N ${\mathrm{H}}_{4}$ ${\mathrm{H}}_{2}$ P ${\mathrm{O}}_{4}$ pumped at 3472 \AA{}.A quantum theory is developed for the spontaneous optical parametric process in nonlinear, anisotropic, and dispersive media; the process is treated directly as a scattering problem rather than a problem involving equivalent coupled oscillators. Following the general procedure in quantum field theory, a general expression is obtained for the differential extinction coefficient, which contains all the information on the intensity of the spontaneous emission in the parametric scattering process. The tuning characteristics, beam divergence, and spectral properties of the spontaneous emission for colinear and noncolinear interactions are described in detail and illustrated with numerical examples on such standard nonlinear optical crystals as LiNb${\mathrm{O}}_{3}$, N${\mathrm{H}}_{4}$${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$, and K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$ under various pumping conditions. Explicit formulas for the intensity of the spontaneous emission are also obtained. The spontaneous intensity calculated using the formulas given is shown to be in complete agreement with known experimental data on N${\mathrm{H}}_{4}$${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$ pumped at 3472 \AA{}.

Physical ReviewFeb 10, 1968112 citations

Master equation for amplified spontaneous emission

C. R. Willis

Physics Letters AAug 1, 19714 citations

Energy extraction from pulsed amplified stimulated emission lasers operating under conditions of strong saturation

S. M. Hooker, David James Spence

The output of pulsed, homogeneously broadened amplified spontaneous emission (ASE) lasers operating under conditions of strong saturation is considered. An expression for the maximum power (energy) per unit volume that may be extracted from steady-state (pulsed) systems is derived and shown to be independent of the saturation intensity. Numerical calculations of the temporal evolution of the populations in the laser levels and the growth in the ASE fluence, peak intensity, and spectral width are presented for three types of laser system: quasi steady state, short pump pulses, and self-termination. In all cases the growth in the fluence of the ASE pulse is found to agree with an analytic solution derived for conditions of strong saturation. The calculated growth in intensity of the ASE pulse is compared with expressions derived by Pert [J. Opt. Soc. Am. B11, 1425 (1994)] for the steady-state case. As expected, good agreement is found for the quasi-steady-state system, but in the limit of strong saturation significant differences occur for the short pump pulse and self-terminating laser systems considered. For all cases considered, the variation of the spectral width of the ASE pulse is found to be in reasonable agreement with that predicted by Pert for steady-state conditions.The output of pulsed, homogeneously broadened amplified spontaneous emission (ASE) lasers operating under conditions of strong saturation is considered. An expression for the maximum power (energy) per unit volume that may be extracted from steady-state (pulsed) systems is derived and shown to be independent of the saturation intensity. Numerical calculations of the temporal evolution of the populations in the laser levels and the growth in the ASE fluence, peak intensity, and spectral width are presented for three types of laser system: quasi steady state, short pump pulses, and self-termination. In all cases the growth in the fluence of the ASE pulse is found to agree with an analytic solution derived for conditions of strong saturation. The calculated growth in intensity of the ASE pulse is compared with expressions derived by Pert [J. Opt. Soc. Am. B11, 1425 (1994)] for the steady-state case. As expected, good agreement is found for the quasi-steady-state system, but in the limit of strong saturation significant differences occur for the short pump pulse and self-terminating laser systems considered. For all cases considered, the variation of the spectral width of the ASE pulse is found to be in reasonable agreement with that predicted by Pert for steady-state conditions.

Journal of the Optical Society of America BJun 1, 20062 citations

{\mathrm{O}}_{3}

, N

{\mathrm{H}}_{4}

{\mathrm{H}}_{2}

{\mathrm{O}}_{4}

, and K

{\mathrm{H}}_{2}

{\mathrm{O}}_{4}

under various pumping conditions. Explicit formulas for the intensity of the spontaneous emission are also obtained. The spontaneous intensity calculated using the formulas given is shown to be in complete agreement with known experimental data on N

{\mathrm{H}}_{4}

{\mathrm{H}}_{2}

{\mathrm{O}}_{4}

pumped at 3472 \AA{}.