G. G. Padmabandu

Observation of V-Type Electromagnetically Induced Transparency in a Sodium Atomic Beam

We have conducted an experimental study of V-type electromagnetically induced transparency in sodium. Its principles are elucidated by a simple model. Measurements show decreased fluorescence and absorption depending on the detuning of the driving and probe fields, which is in agreement with the results of numerical simulation.

Coherent effects in forward scattering

Light scattering at near forward angles has received considerable attention in the past. However, measurements below a scattering angle of 0.1 degree(s) have not previously been made for particle suspensions due to the presence of the unscattered incident light beam. In this paper, we review a new technique for measuring light scattering near, as well as precisely at, a scattering angle of zero degrees. The existence of coherent scattering effects at zero degrees is considered and both theoretical predictions and experimental data are presented.

ANGULAR DISTRIBUTION OF THE FORWARD LIGHT SCATTERING FROM A QUARTZ FIBER

Using a new technique based on the fanning of a coherent light beam in a photorefractive BaTiO(3) crystal, we have measured the angular distribution of forward light scattering by quartz fibers of radii from 15 to 30 µm. Data have been obtained over the angular range 0° to 0.3° and are in good agreement with theory.

Atomic coherence effects within the sodium D1 manifold. III: Lasing without inversion via population trapping

Transient lasing without inversion has been experimentally demonstrated in sodium vapour. The principle of this atomic coherence effect can be well understood from the theory of a simple four-level system. The experimental results match with numerical simulations which take the complete hyperfine structure of the sodium D1 line into account. The differences between our system and a Raman laser are discussed.

Measurement of light scattering at 0° by micrometer-size quartz fibers

Measurements of light scattering by a quartz fiber at an angle of 0° have been made by using the 0.5145-μm line from an Ar+ laser. Data have been obtained as a function of fiber radius from 1 to 32 μm, and they are in excellent agreement with theory. This new measurement technique is based on the fanning of a coherent light beam in a photorefractive BaTiO3 crystal.

Angular momentum of light and its effect on a birefringent medium

The mechanical torque exerted by a beam of polarized light on a half waveplate that alters the state of polarization is calculated for several laser wavelengths and intensities using electromagnetic theory. The second-order torque that arises through the nonlinear interaction is formulated, and the numerical values are obtained for the 42 m crystal class. The experiment used to detect the existence of the torque is reviewed and a demonstration experiment is suggested.

Measurement of light scattering at 0 degrees by small-particle suspensions

Measurements of the intensity of the light scattered by 1 1 im polystyrene spheres suspended in water have been made as a function of angle from -0.05° to 0.05°. Data have also been obtained for scattering at O as a function of particle concentration. As the particle concentration Increases the sample transmission decreases monotonically but the scattered light intensity at O Increases monotonically as expected. This new measurement technique Is based on coherent two beam coupling In a photorefractive BaTIO3 crystal.