Gain, in laser

Nowadays, sophisticated cooling techniques have been available to ensure the laser materials to be operated at cryogenic temperatures, in which the costs can be weU compensated by the advantages that can be gained in laser performances. Spectroscopic advantages include increased emission cross section and reduced population of the terminal level that transforms the 1030 nm emission of the strong transition of F5/2(l) into a four-level scheme, while material properties... 

Stimulated Raman spectroscopy is a useful introduction to coherent effects in optical spectroscopy. A discussion of coherent excitation can be used to make the connection between optical spectroscopy and nuclear magnetic resonance spectroscopy clear. The relation of the stimulated Raman effect to gain in lasers provides a hook to another important topic. 

It should be noted that there is a limited number of works on classical relativistic dynamical chaos (Chernikov et.al., 1989 Drake and et.al., 1996 Matrasulov, 2001). However, the study of the relativistic systems is important both from fundamental as well as from practical viewpoints. Such systems as electrons accelerating in laser-plasma accelerators (Mora, 1993), heavy and superheavy atoms (Matrasulov, 2001) and many other systems in nuclear and particle physics are essentially relativistic systems which can exhibit chaotic dynamics and need to be treated by taking into account relativistic dynamics. Besides that interaction with magnetic field can also strengthen the role of the relativistic effects since the electron gains additional velocity in a magnetic field. 

Recently, DNA has been studied as a robust material for photonics applications32, and particularly as a polymer matrix in laser gain material33. This material can withstand high-intensity laser fields and relatively high temperatures. 

Detailed information about collision-induced, vibrational, or rotational excitation and deactivation has been collected from much work on molecular lasers, expecially the COj laser 1. If the intensity of a laser line is sufficiently high, its gain in an amplifying medium saturates and is then determined by the number of molecules excited per second into the upper laser level and by the depopulation rate of the lower level. Measuring the saturation behaviour under different pressures and discharge currents allows the excitation and deactivating processes to be studied Observation of the... 

Raman scattering is a method that has been used to a small extent for solutions so far, but is likely to gain in popularity with the introduction of laser light sources, because it is capable of quantitative estimation of the species involved. A limitation is the necessity to use rather concentrated solutions, which can be a source of complications when solution equilibria are involved, but this... 

An important difference between luminescent conjugated polymers and laser dyes is that the former still exhibit strong optical gain in the solid state. This property means that luminescent conjugated polymers can be used to produce stimulated emission in thin films of these materials. 

A major development reported in 1964 was the first numerical solution of the laser equations by Buley and Cummings [15]. They predicted the possibility of undamped chaotic oscillations far above a gain threshold in lasers. Precisely, they numerically found almost random spikes in systems of equations adopted to a model of a single-mode laser with a bad cavity. Thus optical chaos became a subject soon after the appearance Lorenz paper [2]. 

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