As a result of development of optics during many centuries the concept was formed that a medium can strongly influence on the light propagation, but the light itself cannot have backward influence on the medium. That concept was refuted only with appearing of coherent and high power radiation of lasers, see, e.g., Nobel Lecture by N. Bloembergen in 1981. A new field in physics–nonlinear optics—formed as a result. The main part of laser investigations concerns with nonlinear optical phenomena, nowadays. First of all these phenomena are of extraordinary interest and beauty and provide for new methods of physical investigations. Secondly, the knowledge of laws governing the interaction of a powerful light with a medium is necessary for the correct utilization of laser beams. Finally, a great number of devices of up-to-date laser optics is totally based on utilization of nonlinear optical effects; generation of higher harmonics of light, stimulated scattering of light, optical phase conjugation, self...

Orientational Optical Nonlinearity of Liquid Crystals

Recently, mode instability was observed in optical fiber lasers at high powers, severely limiting power scaling for single-mode outputs. Some progress has been made towards understanding the underlying physics. A thorough understanding of the effect is critical for continued progress of this very important technology area. Mode instability in optical fibers is, in fact, a manifestation of stimulated thermal Rayleigh scattering. In this work, a quasi-closed-form solution for the nonlinear coupling coefficient is found for stimulated thermal Rayleigh scattering in optical fibers. The results help to significantly improve understanding of mode instability.

Stimulated thermal Rayleigh scattering in optical fibers.

The broad bandwidth and long storage lifetimes of Nd3+: glass and ruby lasers have made possible the generation of picosecond laser pulses having peak powers it excess of one gigawatt and repetition rates in the microwave range. The numerous application areas of these pulses include research in nonlinear optics, transient response of atomic and molecular systems, optically generated plasmas, spectroscopy, ranging, optical information processing, and high-speed photography. This paper reviews several experimental techniques for generating, measuring, and utilizing these ultrashort laser pulses.

Picosecond laser pulses

Picosecond Laser Pulses

Tensor‐algebra techniques are used to derive expressions similar to those of Pecora and Steele for light scattering by liquids of anisotropic molecues, in a more compact form. The correlation functions are cast into a form in which their geometrical meaning is made obvious and is more immediately applicable to liquid models. A generalization of the Kirkwood g factor to second‐rank tensors is defined. The theory is applied to the depolarized Rayleigh wings. It is argued on the basis of intensity and half‐width measurements that the diffuse line, which appears in the spectrum of benzene and several benzene derivatives, originates from reorientation of single molecules. This conclusion fits into a broader scheme incorporating results of dielectric, NMR, and viscosity measurements. It is suggested to relate the background, together with the narrow hole in the middle of the depolarized spectrum, to couplings of orientational fluctuations with shear waves.

Light Scattering by Orientational Fluctuations in Liquids

Stimulated Thermal Rayleigh Scattering

Stimulated Rayleigh Scattering

Stimulated Thermal Rayleigh Scattering in Gases

Stimulated Thermal Rayleigh Scattering in Liquids

Optical mixing in 23 liquids and 2 glasses is reported. Observations with a high-resolution grating spectrograph of the light from a giant-pulse ruby laser transmitted through the materials reveal the presence of more Stokes-shifted components than can be accounted for on the basis of amplification by the laser of Brillouin-shifted frequencies. In addition, anti-Stokes-shifted components are observed. The frequency shifts are shown to correspond to those expected for 180° Brillouin scattering. Sound speeds calculated agree in general with those from stimulated and spontaneous scattering experiments. Sound-speed measurements at different temperatures and for two-component liquids give results predictable from bulk properties of the liquids. A number of experiments showing the conditions and the parameters which affect the optical mixing are described.

C. W. Cho

Papers

Stimulated Thermal Rayleigh Scattering

Stimulated Rayleigh Scattering

Stimulated Thermal Rayleigh Scattering in Gases

Stimulated Thermal Rayleigh Scattering in Liquids

Optical Mixing in Stimulated Brillouin Spectra