Ruby solid-state laser

Doping, which involves the intentional incorporation of atoms or ions of suitable elements into host lattices, is one of the effective routes to endow electronic, magnetic, and optical properties of many functional materials. An excellent example is the ruby solid-state laser where the Cr -doped AI2O3 crystal is used as the gain medium. It is now generally anticipated that the performances of the bulk materials are more or less different to those of the same materials in... 

Lasers produce spatially narrow and very intense beams of radiation, and lately have become very important sources for use in the UV/VIS and IR regions of the spectrum. Dye lasers (with a fluorescent organic dye as the active substance) can be tuned over a wavelength range of, for instance, 20-50 nm. Typical solid-state lasers are the ruby laser (0.05% Cr/Al203 694.3 nm) and the Nd YAG laser (Nd3+ in an yttrium aluminium garnet host 1.06 pm). 

Solid-state lasers, such as the ruby laser, neodymium doped yttrium aluminium garnet (Nd-YAG) laser and the titanium doped sapphire laser. 

There are many solid state lasers. One of the most commonly treated types in laser textbooks is the ruby laser (Al203 Cr +), which was the first laser system demonstrated by T. H. Maiman at the Hughes Research Laboratory early in 1960 (Maiman, 1960). Figure 6.9 in Chapter 6 will show the quantum energy levels associated with the unfilled 3d inner shell of the Cr + ion when it substitutes for the AP+ ion in the AI2O3 lattice crystal. By using a ruby rod placed inside a spiral flashlamp filled with a hundreds of torrs of xenon, it is possible to optically pump Cr + ions from the " A2g ground state into the broad " T2 and " Ti bands of the excited levels. After a rapid relaxation down to the very sharp Eg level, laser emission can be produced at 694 nm via the Eg " A2g transition. 

The most important application of the nonlinear absorption characteristics of dye solutions is the so-called passive Q-switching of solid-state lasers, in particular ruby lasers emitting at 694.3 nm and neodymium lasers emitting at 1.064 /tm. 

Sometimes 3(d — n ) and k ) states are said to be derived from delocalized orbitals and d—d) state from localized orbitals. The shift of the chelate emission from that of the free ligand increases in the sequence Rh(III) < Ir(III) < Ru(II) and reflects increasing cf-orbital participation in the emission orbital. The decrease in the chelate emission lifetime from the free ligand values also reflect the contamination of the molecular orbitals with d-character. The role of metal complexes as quenchers of excited states of it-electrons in organic compounds can be rationalized from such considerations. Emission from Cr8+ is the basis of one of the most important solid state laser system, the Ruby laser (Figure 10.14). 

Solid-state lasers -dopant for ruby laser [LASERS] (Vol 15)... 

The first reported laser action in rare earth complexes was obtained by Lempicki and Samelson [656] for europium benzoylacetonate in alcoholic solution. The laser parameters for this complex have also been evaluated by Lempicki and coworkers [656, 660] who found a slightly better quantum efficiency (0.8) for europium benzoylacetonate than for ruby (0.7), the solid state laser. The laser action of europium benzoylacetonate has also been investigated by Schimitschek [661] and Bhatjmik et al. [662]. Some other complexes of Eu3+ viz. dibenzoylmethide [665,664], m-4,4,4-trifluoro-l(2-thienyl)-l,3-butanedione [665], thenoyl-trifluoroacetonate [666, 667] were also found to lase. 

A diode, or semiconductor, laser operates in the near-infrared and into the visible region of the spectrum. Like the ruby and Nd3+ YAG lasers it is a solid state laser but the mechanism involved is quite different. 

The non-relativistic version of DVME method was developed in 1998 and was applied to the analysis of multiplet spectra of ruby [6-8]. This method was later applied to the analysis of a variety of TM-doped solid-state-laser materials [9-11]. The relativistic version of DVME method was developed in 2000. However, at that time, it was still difficult to calculate multiplet spectra of RE ions due to the limited performance of available computers. On the other hand, the relativistic... 

Solid-State Lasers Radiative Properties of Ruby Crystals Spectroscopic Properties of CdSe Nanocrystals... 

The first optical laser, the ruby laser, was built in 1960 by Theodore Maiman. Since that time lasers have had a profound impact on many areas of science and indeed on our everyday lives. The monochromaticity, coherence, high-intensity, and widely variable pulse-duration properties of lasers have led to dramatic improvements in optical measurements of all kinds and have proven especially valuable in spectroscopic studies in chemistry and physics. Because of their robustness and high power outputs, solid-state lasers are the workhorse devices in most of these applications, either as primary sources or, via nonlinear crystals or dye media, as frequency-shifted sources. In this experiment the 1064-mn near-infrared output from a solid-state Nd YAG laser will be frequency doubled to 532 nm to serve as a fast optical pump of a raby crystal. Ruby consists of a dilute solution of chromium 3 ions in a sapphire (AI2O3) lattice and is representative of many metal ion-doped solids that are useful as solid-state lasers, phosphors, and other luminescing materials. The radiative and nonradiative relaxation processes in such systems are important in determining their emission efficiencies, and these decay paths for the electronically excited Cr ion will be examined in this experiment. 

The study of optical centers in solids, liquids, and molecules has fascinated many scientists over a range of years. However, not only scientific curiosity has pushed forward this type of spectroscopy. Simultaneously, many possible applications became clear. The first solid state laser was based on a ruby crystal. Also, in the development of tunable infrared lasers the Cr " " ion played an important role. 

Although the first laser demonstrated was a solid state ruby laser, for many years the most common commercial systems were gas lasers such as helium neon lasers and argon ion lasers, or lasers based on organic dyes. Helium neon lasers were frequently limited in output power, argon ion lasers required expensive, sophisticated power supplies and cooling sources, and the dyes used in dye lasers were messy and often toxic. In the past decade, solid state lasers and diode lasers have become the dominant players in the commercial marketplace. 

In solid-state laser materials, such as ruby (chromium doped alumina, AljOjiCr " ) (1) and emerald (chromium doped beryl, Be,Al,(Si03)5 Cr ) (2), transitions between multiplets of impurity states are utilized. These states mainly consist of 3d orbitals of the impurity chromium ions. For the analysis of these multiplet structures, the semi-empirical ligand-field theory (LFT) has been frequently used (3). However, this theory can be applied only to the high symmetry systems such as O, (or T ). Therefore, the effect of low symmetry is always ignored in the analysis based on the LFT, although most of the practical solid-state laser materials actually possess more or less distorted local structures. For example, in ruby and emerald, the impurity chromium ions are substituted for the aluminum ions in the host crystals and the site symmetry of the aluminum ions are C, in alumina and D, in beryl. Therefore, it is important to clarify the effect of low symmetry on the multiplet structure, in order to understand the electronic structure of ruby and emerald. 

Invention of ruby laser, the forerunner of all solid-state lasers... 

If you are surprised, remember the gemstone ruby (Al Oj Cr ) mentioned in the beginning of this chapter. Becqgerel started long ago to. study its luminescence and spectroscopy. Ruby was and is the start of several interesting phenomena in solid state physics. Probably the most important of these is the first solid state laser which was based on mhy (Maiman, I960). This illustrates the connection between luminescence and lasers. On the other hand, in more recent years it has only been possible to unravel and understand luminescence processes by using laser spectroscopy. 

In view of the latter rem the phenomenon of stimulated emission has been mentioned, and certain laser materials will be mentioned later in this book. History illustrates this by the fact that ruby, investigated long ago by Becquerel, is the material on which the Krst solid state laser was based. In this chapter the return from the excited stale to the ground state was assumed to be radiative only. The next chapter considers nonradiative transitions. 

---