Lasers basics

Stevens, Lawrence. Laser Basics. Englewood Qiffs, NJ Prentice Hall, 1985. 

As has been pointed out above, a laser basically consists of an active material and a resonator. The latter enables the build-up of certain resonant modes and essentially determines the lasing characteristics. In most conventional devices, the optical feedback is provided by an external cavity with two end mirrors forming the resonator. With the advent of polymers as active materials, various new feedback structures were invented. Initially, a microcavity resonator device of the type shown schematically in Fig. 6.13 a was employed [48]. 

Dirscherl M (2008) Ultrashort pulse lasers - basic principles and applications. Bayerisches Laserzentrum GmbH... 

Basic brown 4, dihydrochloride Basic orange 2 Dianisidine Direct blue 1 Direct yellow 11 Manganese sulfate (ous) Vat yellow 4 dye, textiles leather Acid orange 3 dye, thermoplastics Disperse yellow 54 dye, triacetate Disperse blue 72 dye, tunable lasers Basic red 1 dye, varnishes... 

Z. Cocagne, Fiber lasers basic theory manufacturing and applications. http //mechanical. illinois.edu/media/uploads/course websites/cocagne fiber lasers.20100420. 4bce8145cec420.36594601.pdf... 

Silfvast, William Thomas. Laser Fundamentals. 2d ed. New York Cambridge University Press, 2004. Covers topics from laser basics to advanced laser physics and engineering. 

The AET was used at standard tests of numerous structural materials, above all steels and cast iron, prepared are ceramic samples. Part of tested samples had qjecial sur ce layer treatments by laser, plasma nitridation and similar. Effect of special surface treatment the authors published already earlier [5,6]. In this contribution are summed up typical courses of basic dependencies, measured by the AET at contact loading. 

Modem photochemistry (IR, UV or VIS) is induced by coherent or incoherent radiative excitation processes [4, 5, 6 and 7]. The first step within a photochemical process is of course a preparation step within our conceptual framework, in which time-dependent states are generated that possibly show IVR. In an ideal scenario, energy from a laser would be deposited in a spatially localized, large amplitude vibrational motion of the reacting molecular system, which would then possibly lead to the cleavage of selected chemical bonds. This is basically the central idea behind the concepts for a mode selective chemistry , introduced in the late 1970s [127], and has continuously received much attention [10, 117. 122. 128. 129. 130. 131. 132. 133. 134... 

Chu B 1991 Laser Light Scattering, Basic Principies and Practice 2nd edn (New York Academic) (See also the first edition (published in 1974) that contains more mathematical derivations.)... 

The basic Hamiltonian describing the motion of atoms and molecules under a strong laser is simple in the dipole approximation,... 

A logical consequence of this trend is a quantum w ell laser in which tire active region is reduced furtlier, to less tlian 10 nm. The 2D carrier confinement in tire wells (fonned by tire CB and VB discontinuities) changes many basic semiconductor parameters, in particular tire density of states in tire CB and VB, which is greatly reduced in quantum well lasers. This makes it easier to achieve population inversion and results in a significant reduction in tire tlireshold carrier density. Indeed, quantum well lasers are characterized by tlireshold current densities lower tlian 100 A cm . ... 

The history of tire diode laser illustrated in figure C2.16.11 shows tire interiDlay of basic device physics ideas and teclmology. A new idea often does not produce a better device right away. It requires a certain leap of faitli to see tire improvement potential. However, once tire belief exists, tire teclmology can be developed to demonstrate its validity. In tire case of diode lasers, tire better teclmology was invariably associated with improved epitaxial growtli. 

Figure C3.1.1. The basic elements of a time-resolved spectral measurement. A pump source perturbs tlie sample and initiates changes to be studied. Lasers, capacitive-discharge Joule heaters and rapid reagent mixers are some examples of pump sources. The probe and detector monitor spectroscopic changes associated with absorjDtion, fluorescence, Raman scattering or any otlier spectral approach tliat can distinguish the initial, intennediate and final...

Future Trends. Methods of laser cooling and trapping are emerging as of the mid-1990s that have potential new analytical uses. Many of the analytical laser spectroscopies discussed herein were first employed for precise physical measurements in basic research. AppHcations to analytical chemistry occurred as secondary developments from 10 to 15 years later. 

W. Demtritder, Laser Spectroscopy Basic Concepts and Instrumentation, 2nd ed., Springer-Vedag, Berlin, 1996. 

Dyes derived from these fundamental basic and acidic terminal groups are in current use today as photographic spectral sensiti2ers [100471-81 -6] (10), chemotherapeutic dyes [54444-00-7] (11), laser dyes [53655-17-7] (12), and biological stains [7423-31-6] (13) (Fig. 4). 

Reaction with vatious nucleophilic reagents provides several types of dyes. Those with simple chromophores include the hernicyanine iodide [16384-23-9] (20) in which one of the terminal nitrogens is nonheterocyclic enamine triearbocyanine iodide [16384-24-0] (21) useful as a laser dye and the merocyanine [32634-47-2] (22). More complex polynuclear dyes from reagents with more than one reactive site include the trinuclear BAB (Basic-Acidic-Basic) dye [66037-42-1] (23) containing basic-acidic-basic heterocycles. Indolizinium quaternary salts (24), derived from reaction of diphenylcyclopropenone [886-38-4] and 4-picoline [108-89-4] provide trimethine dyes such as (25), which absorb near 950 nm in the infrared (23). 

It is said that necessity is the mother of invention. This adage says volumes about the early development of the laser. Unring World War II, U.S. mihtaiy and civilian scientists searched frantically for improved radar. Wliile these researchers met with only mixed success, their efforts spurred basic research. After the war, using knowledge gained from this line of inquiiy, the first successful laser was developed in 1960. 

The word laser is an acronym for light amplification by the stimulated emission of radiation. Lasers of all kinds consist of several basic components an active medium, an outside energy source, and an optical cavity with carefully designed mirrors on both ends. One of the mirrors is 100 percent reflective... 

The laser has revolutionized many aspects of science and other disciplines, as well as the daily lives of millions of people. When it was first invented, the laser was referred to by some as a solution looking for a problem because it came about mostly from basic research rather than the active solution to a particular concern. At the time, no one could have predicted the far-reaching effects it would have in the second half of the twentieth centuiy, or that it would come to be considered by many as one of the most inQuen-tial technological achievements of that time. 

In an attempt to develop the hydrogen bomb before the Russians, a second weapons laboratory , Lawrence Livermore, was established in July 1952 to handle the additional work that would be necessaiy to stay ahead of the Russian nuclear weapons program. The administrator chosen was the University of California. Eor the next forty-five years, this LLNL was a formidable competitor to Los Alamos in the development of nuclear weapons. But much like most of the other major national laboratories, its focus also shifted away from nuclear weapons to basic science to fields like magnetic and laser fusion energy, non-nuclear energy, biomedicine, and environmental science. By the late 1990s, half of the laboratoi y s budget was nonde-fense related as the shift away from nuclear weapons continued. 

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