Solid state tunable laser, applications

Reisfeld R., Seybold G. Solid state tunable lasers in the visible based on luminescent photoresistant heterocyclic colorants. Chimia 1990 44 295-297 Reisfeld R. Spectroscopy and applications of molecules in glasses. J. Non-Cryst. Solids 1990 121 254-266... 

Tunable gas phase lasers are expensive. Less expensive solid-state diode lasers with wavelengths in the NIR are available. Commercial instmments using multiple diode lasers are available for NIR analyses of food and fuels. Because of the narrow emission lines from a laser system, laser sources are often used in dedicated applications for specific analytes. They can be ideal for process analysis and product quality control, for example, but are not as flexible in their applications as a continuous source or a tunable laser. 

Enhancement of x2 will lead to improvement (in terms of efficiency per interaction volume) in the following applications up-conversion in the visible or near U.V. of powerful I.R. laser radiation, frequency modulation of a laser carrier beam, optical parametric oscillation and amplification for solid state infrared tunable coherent devices. 

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. 

The laser-based methods make use of different types of laser sources. Many of them, such as the solid-state laser or the semiconductor laser, are under continuous development because of the discovery of new lasing materials or the optimization of frequency conversion techniques. The type of the analytical application and the nature of the required information determine the choice of a special laser source, particularly pulsed or continuous-wave (CW) operating mode. Pulsed laser sources with fixed wavelength are usually used for LA, whereas both tunable pulsed and CW laser sources are preferred for element-specific detection or plasma diagnostics. 

In this section we discuss experimental realizations of some tunable lasers, which are of particular relevance for spectroscopic applications. A variety of tuning methods have been developed for different spectral regions, which will be illustrated by several examples. While semiconductor lasers, color-center lasers, and vibronic solid-state lasers are the most widely used tunable... 

Besides their applications as tunable light sources, diode lasers are more and more used as pump lasers for tunable solid-state lasers and optical parametric amplifiers. Monolithic diode laser arrays can now deliver up to lOOWcw pump powers [5.124]. 

Intracavity frequency doubling of these lasers (Sect. 5.8) covers the visible and near-ultraviolet range [5.133]. Although dye lasers are still the most important tunable lasers in the visible range, these compact and handy solid-state devices present attractive alternatives and have started to replace dye lasers for many applications. 

The future prospects for selective chemistry research as an aspect of laser development are not as bright as several years ago. With the exception of the quest for a visible chemical laser, most new laser research is oriented towards systems that are patently nonmolecular. The leading candidate for very high power applications is the free electron laser (PEL). In this device, the interaction of a relativistic electron beam with a periodic magnetic structure produces coherent radiation. Such devices on paper can have substantially higher power and efficiency than electric molecular lasers. For moderate power applications, advances in solid state lasers, nonlinear optical conversion processes, and tunable solid state media offer the prospect of broadly tunable compact sources. At low powers, diode lasers and diode laser arrays are gaining increasing application and hold out the promise, when used with solid state media, of versatile tunable sources. 

---