Slab geometry solid-state lasers offer significant performance improvements over conventional rod geometry lasers. We present a detailed theoretical description of the thermal, stress, and beam propagation characteristics of a slab laser. Our analysis includes consideration of the effects of the zig-zag optical path which eliminates thermal and stress focusing and reduces residual birefringence.

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The slab geometry laser - Part I: Theory

Resonators containing a focusing rod are thoroughly analyzed. It is shown that, as a function of the dioptric power of the rod, two stability zones of the same width exist and that the mode volume in the rod always presents a stationary point. At this point, the output power is insensitive to the focal length fluctuations, and the mode volume inside the rod is inversely proportional to the range of the input power for which the resonator is stable. The two zones are markedly different with respect to misalignment sensitivity, which is, in general, much greater in one zone than in the other. Two design procedures are presented for monomode solid-state laser resonators with large mode volume and low sensitivity both to focal length fluctuations and to misalignment.

Resonators for solid-state lasers with large-volume fundamental mode and high alignment stability.

This review considers the technique of thermal lens spectrometry and its applications to chemical measurements in solid, liquid and gaseous phases. Practical applications, theoretical treatments and instrumental developments are considered in terms of their analytical use and potential.

Thermal lens spectrometry. A review

Phase conjugation by stimulated Brillouin scattering represents a fundamentally promising approach for achieving power scaling of solid-state lasers. Following a summary of the power scaling problem and an overview of phase conjugation concepts, a review is presented of the application of phase conjugation to solid-state lasers. The author describes power scaling using demonstrated techniques for compensating static and thermally induced aberrations and depolarizations, as well as energy scaling by coherent coupling of multiple-gain media. Applications to diode-pumped lasers are discussed, as is a novel approach for power scaling of diode lasers themselves. Future research directions are indicated regarding conjugation fidelity at increasingly higher energies or with short-pulse and/or broadband lasers. >

A review of phase-conjugate solid-state lasers

YAG single crystals are the primary host materials for solid-state lasers at multi-kW scale and must be processed using ultra-precision grinding to achieve a satisfactory dimensional precision and surface integrity. However, the deformation mechanism of YAG crystals is not well understood, which has thus hindered the development of high efficiency grinding technology for the crystals. In this work, precision grinding of YAG single crystals was investigated. Ductile-like surfaces that are free of cracks and brittle-ductile surfaces that consist of fractured spots and ductile striations were found after grinding. The deformation mechanisms associated with the two types of surfaces were explored with the aid of transmission electron microscopy (TEM). The results indicated that the deformation involved in the formation of the ductile-like surface was mainly caused by the slippage of (0 0 1) crystal planes, along with the formation of dislocations and stacking faults and the distortion of atomic planes. The brittle-ductile surfaces were generated by the plastic deformation due to the formation of nanocrystals and nanovoids, combined with brittle fracture caused by the crack propagation initiated at intersections of slip lines. A theoretical model was developed to predict the grinding force in the ductile-like grinding process, which has taken the combined effect of strain rate, random distribution of abrasive radii and elastic-to-plastic transition depth into account for the first time. The key model parameters were obtained using a genetic algorithm trained using the experimental force data. The modelled force agrees well with the measured. This model enabled an in-depth understanding of the deformation mechanism of a crystal solid involved in ultraprecision grinding and the effect of strain rate on its material removal.

Deformation mechanism and force modelling of the grinding of YAG single crystals

A theoretical model for the thermal lens and birefringent effects induced in a continuously pumped Nd:YAG rod is developed. Experimental measurements of these effects using a 6328‐A probe are described and compared to theory. Excellent agreement between the two types of measurements and theory is obtained. The thermally birefringent and bifocusing phenomena are suggested as causes of reductions in the polarized and fundamental TEM00 powers from a high‐power multimode Nd:YAG laser. Typical results are described using a laser which operates in the 200−300‐W range of average powers.

J. D. Foster

Papers

Thermal Effects in a Nd:YAG Laser