Publisher Summary This chapter describes the symmetry aspects of the crystal field and the parametrization of the energy level scheme. It provides an overview of the experimental data of trivalent lanthanide ions doped into crystalline host matrices. The selection rules for induced electric dipole (ED) and magnetic dipole (MD) transitions for systems with even or odd numbers of f electrons in different site symmetries are presented. Methods for the assignment of crystal-field levels are discussed and the determination of phenomenological crystal-field parameters is described. Such a set of crystal-field parameters in combination with a suitable set of free-ion parameters allows calculating crystal-field energy levels and reconstructing the energy diagram of the 4fn configuration. In this way, it is not only possible to check the validity of the crystal-field model but also to get information about energy levels, which cannot be detected experimentally.

Chapter 155 Rationalization of crystal-field parametrization

Publisher Summary The intensities of intraconfigurational f–f transitions are reviewed in the chapter The chapter presents the transition mechanisms for lanthanide ions—namely, the magnetic dipole transition, the induced electric dipole transition, and the electric quadrupole transition It discusses the way experimental intensities can be determined from the spectra The chapter also focuses on the expression of the dipole strength and the oscillator strength in oriented and in randomly-oriented systems Correction factors for lanthanide ions in a dielectric medium are described in the chapter Although only a few magnetic dipole transitions exist for the trivalent lanthanide ions, magnetic dipole transitions are of interest, because their intensities are in a first approximation independent of the ligand environment and can, thus, be used as intensity standards The intensity of a magnetic dipole transition can be calculated exactly, provided that suitable wavefunctions are available These wavefunctions can be obtained from diagonalization of the energy matrix

Chapter 167 Spectral intensities of f-f transitions

After a brief examination of known insulating laser crystals and the stimulated emission channels of their generating activator ions, this article reviews recent advances in the development of novel lasing crystals and ceramics, as well as inorganic and organic nonlinear-laser crystals for χ(3) and cascaded χ(3) ↔ χ(2) frequency converters Several new modern attractive technologies in the physics and techniques of crystalline lasers are also discussed

https://onlinelibrary.wiley.com/doi/pdf/10.1002/lpor.200710008

Laser crystals and ceramics: recent advances

Reviews the basic physics of tunable solid-state lasers and discusses the characteristics of the most significant established and emerging systems. Particular emphasis is placed on trivalent transition metals; alexandrite, other Cr-doped systems, and Ti: sapphire are also discussed. Other systems, rare earth and forsterite, are considered. >

Tunable solid-state lasers

Laser action in chromium‐doped forsterite (Cr: Mg2SiO4), pumped with a 1.064 μm Nd:YAG laser, was demonstrated for the first time. The free‐running laser emission is centered at 1.221 μm and has a spectral width of 28 nm. An efficiency of 8% has been achieved with an uncoated crystal produced by the laser‐heated‐pedestal growth method. The available evidence suggests that the laser action is due to Cr4+ in tetrahedral sites.

Chromium-doped forsterite laser pumped with 1.06 μm radiation

Chromium‐doped forsterite laser pumped with 1.06 μm radiation

We report the first observation, to our knowledge, of three‐level laser oscillator operation in a crystal activated with Mn5+. The material is Mn:Ba3(VO4)2 which exhibited laser oscillation at room temperature under pulsed 592 nm excitation. The laser emission occurs at 1181 nm with a threshold of 0.3 J/cm2. Spectroscopy indicates that this material operates as a three‐level system on the 1E to 3A2 transition of the Mn5+ ion with tetrahedral coordination. The strong, broad absorption bands and 0.43 ms room‐temperature lifetime make this system very promising for flash lamp AlxGa1−xAs diode pumping.

Laser action from Mn5+ in Ba3(VO4)2

Preparation, structure, and spectroscopic properties of Nd3+:{La1-xLux}3

The polarized absorption and emission spectra of chromium-aluminum-doped forsterite grown in argon- and oxygen-containing atmospheres are presented, and the relation between the growth atmosphere and the oxidation state of chromium in forsterite and aluminum-codoped forsterite, as revealed by optical spectroscopy, is discussed. Based on a simple model of the local point symmetry and polarization selection rules derived by group-theoretical considerations, it is concluded that the active center in the chromium-doped forsterite laser is the oxoanion (CrO4)4−. The laser-heated pedestal growth of chromium-doped forsterite crystals codoped with aluminum resulted in a considerable increase in the concentration of the activator that was incorporated by the forsterite host. The pulsed laser performance of a chromium-aluminum-doped forsterite crystal is presented. Using a Q-switched 1064 nm Nd-YAG laser as the pump, and a 1.4 cm long crystal with AR coated ends in the laser cavity, the measured optical conversion efficiency with a 6% transmissive output coupler was about 10%. The round-trip losses determined using this configuration were approximately 3.8%.

Albert Pinto

Papers

Chromium‐doped forsterite laser pumped with 1.06 μm radiation

Chromium-doped forsterite laser pumped with 1.06 μm radiation

Laser action from Mn5+ in Ba3(VO4)2

Preparation, structure, and spectroscopic properties of Nd3+:{La1-xLux}3

Laser Perfomance of Chromium-Aluminum-Doped Forsterite