The possibility of controlling and continuously changing laser emission wavelengths in a wide spectral range without using external elements based on nonlinear optics (to shift the fundamental wavelength) is of primary importance to scientists. With the advent of novel high-power pumping sources, it is possible to design and operate a new class of tunable solid state laser devices for various applications. This book demonstrates the design of new laser materials based on quantum mechanical principles, spectroscopic properties of transition-metal ions, and ion-host interaction. This approach includes the theory of electronic structure of transition-metal ions, modeling of energy transfer and nonradiative processes, and symmetry considerations in spectroscopic analysis of d orbitals.

The possibility of controlling and continuously changing laser emission wavelengths in a wide spectral range without using external elements based on nonlinear optics (to shift the fundamental wavelength) is of primary importance to scientists. However, for years the tunable laser sources were based on liquid dye lasers, which provided only a limited solution to the demand for tunable sources due to their inherent limitations. Since that time there have been impressive advances in experimental and theoretical research in solid state physics, as well as in the optics and spectroscopic properties of solids. Quantum mechanical tools provided further insights into light-matter interaction, photophysical processes, elementary excitations, and host–dopant interactions. Combining those tools with advanced experimental techniques has yielded a means of observing and understanding the optical properties of active ions, such as rare earths and transition metals, and their potential as laser sources. A fundamental understanding of the mutual interactions between the d orbitals of transition-metal ions and the crystal field of various hosts, coupled with the effects of the crystallographic sites and crystalline symmetries, led to a better understanding of ion-host interaction.

Comprehension of the basic spectroscopic and crystallographic properties allowed for the prediction and engineering of new tunable solid state lasers by adjusting the crystal field of a large number of crystalline hosts according to the desired spectral range, from the UV (Ce³⁺-doped crystals) into the visible mid-IR (Cr³⁺- and Cr⁴⁺-doped hosts). With the advent of novel high-power pumping sources, it became possible to design and operate a new class of tunable solid state laser devices for various applications.

This book is a continuation and a companion volume to my previous book The Physics and Engineering of Solid State Lasers (SPIE Press, 2006), and it provides an updated overview of tunable solid state lasers and passive Q-switches based on d-element ions. The main purpose of this monograph is to coherently demonstrate the design of new laser materials based on quantum mechanical principles, spectroscopic properties of transition-metal ions, and ion-host interaction. This approach includes the theory of the electronic structure of transition-metal ions, modeling of energy transfer and nonradiative processes, and symmetry considerations in the spectroscopic analysis of d orbitals. Each chapter features a list of references to support the data and encourage readers to extend their knowledge in the relevant subject.

Another aspect of the transition-metal-ion-doped crystals stems from the unique combination of optical and thermo-mechanical properties that makes them ideal candidates as passive Q-switching devices for Nd:YAG and Yb:YAG lasers. The theory, properties, design, and updated performance of passive Q-switched systems is presented and accompanied with recent advances and applications.

I would like to extend my gratitude to Dr. Gregory J. Quarles (Optoelectronics Management Network, United States) and Prof. David Titterton (DSTL, United Kingdom) for their illuminating remarks and advice. I am especially grateful to my wife, Dr. Ofra Kalisky, for her valuable comments, constant support, and inspiration. Last but not least, I would like to thank SPIE for promoting the idea of writing my second book that facilitates the understanding of d-element lasers and devices. By doing this, interested physicists and engineers can gain an integrated comprehension of lasers and laser technology, based on rare earth and transition-metal ions. I would particularly like to thank Tim Lamkins and Scott McNeill for their patience, flexibility, valuable comments, and continuous support.

Yehoshua Kalisky

Beer Sheva, Israel

December 2013