Showing papers on "Light field published in 1970"
TL;DR: In this paper, a laser amplifier consisting of an ensemble of atoms, three energy levels of which form two coupled transitions of arbitrary frequencies, is treated, and the gain profile (or spontaneous emission) on the transition corresponding to the weak probe wave, modified by the perturbing field on the other transition, is calculated via a susceptibility.
Abstract: A laser amplifier to be treated in this work consists of an ensemble of atoms three energy levels of which form two coupled transitions of arbitrary frequencies. Two classical monochromatic travelling light waves are to be close to resonance with the transitions. The gain profile (or spontaneous emission) on the transition corresponding to the weak “probe” wave, modified by the perturbing field on the other transition, is calculated via a susceptibility. Within this framework, the atoms are described by an ensemble-averaged density matrix with full account of level degeneracies, light polarizations, and inelastic and dephasing collisions; an extension to elastic collisions and disorientation is straightforward. An integration over the thermal velocity distribution gives results applicable to gas discharges: directionally anisotropic narrow structures superimposed on the Doppler-broadened probe-gain profile due to non-linear interference effects in addition to saturation. At alower probe frequency, a peculiar non-Lorentzian signal appears even with transparency on the perturbing transition. At low intensities a distinction is reasonable of frequency correlations due to generalized two-quantum processes, and of a dynamic Stark splitting. These effects permit an information on the linewidth of the third forbidden transition. The connection with numerous related approaches is pointed out.
207 citations
TL;DR: In this paper, a first-order single-ray theory is developed and the predictions of this theory are compared with the data, identifying five refractive effects, the most important of which is the focusing and defocusing of light beams by fluctuations of surface curvature.
Abstract: Irradiance fluctuations in the natural underwater light field close to the sea surface have an amplitude that is of the same order of magnitude as the mean irradiance. A principal source of these fluctuations, differential refraction by surface waves, is examined in this paper, and some experimental data obtained at an experimental site in the Bight of Abaco, Bahamas, are presented. A first-order single-ray theory is developed and the predictions of this theory are compared with the data. The theory identifies five refractive effects, the most important of which is the focusing and defocusing of light beams by fluctuations of surface curvature.
72 citations
TL;DR: In this article, a Twyman-Green interferometer is used in which the orthogonal reference beam is frequency offset with an ultrasonic light modulator and the recombined light field is scanned with an image dissector, and the resulting image displayed on a kinescope.
Abstract: Visualization of ultrasonic wavefields incident on an optically reflecting surface is effected by coherent optical detection of the deformations of this surface. A Twyman‐Green interferometer is used in which the orthogonal reference beam is frequency‐offset with an ultrasonic light modulator. The recombined light field is scanned with an image dissector, and the resulting image displayed on a kinescope.
6 citations
TL;DR: In this article, the quantum-mechanical rate equations for a bulk semiconductor laser that explicitly include a monochromatic light field as a pump source are developed for both pure and doped homogeneous semiconductors.
Abstract: Optical pump experiments on homogeneous samples provide a method of obtaining a clearer understanding of the details of laser action in semiconductors. For this reason, the quantum-mechanical rate equations for a bulk semiconductor laser that explicitly include a monochromatic light field as a pump source are developed. The theory treats general optical transitions and is valid for both pure and doped homogeneous semiconductors. The developed theory gives the intensity of the laser output in the entire region from below to above threshold as a function of the intensity and frequency of the pump field, the temperature, doping level, and material constants. Also the variation of the laser light frequency at threshold upon these parameters is given by the theory. Information about the dependence of the necessary pump intensity and frequency for threshold is gained. The theoretical calculations are compared with experimental measurements and found to be in general agreement.
6 citations
TL;DR: In this article, a quasi distribution function for two circularly polarized modes in a laser with axial magnetic field is calculated, and the solution of the Fokker-Planck equation is given in the stationary case above threshold and in the non-stationary case below threshold.
Abstract: The distribution function for two circularly polarized modes in a laser with axial magnetic field is calculated. If the resonator has different damping constants for waves polarized in different directions, we find a coupling between the modes. To describe this coupling it is necessary to couple both modes to the same heatbath. Starting from a masterequation describing the damping of the atoms and the light field, we may transform the masterequation to a Fokker-Planck equation by introducing a quasi distribution function. By eliminating the atomic variables adiabatically we find a Fokker-Planck equation for the light field variables only. The solution of the Fokker-Planck equation is given in the stationary case above threshold and in the non stationary case below threshold.
3 citations