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Lasers
Published in Abdul Al-Azzawi, Photonics, 2017
The Dye laser was first demonstrated in 1965 at IBM laboratories in the United States of America by Peter Sorokin and J. Lankard. They discovered the Dye laser action during research into fluorescence of organic dye molecules that were excited by a Ruby laser. In 1967, scientists discovered the possibility of tuning the emitted wavelength using a grating at the end of the optical cavity. A Dye laser can be considered as a special device to convert electromagnetic radiation from one wavelength into another tuned wavelength. The output of a Dye laser is always coherent radiation tunable over a specific spectral region, determined by the dye material.
Applications of Laser Absorption Spectroscopy
Published in Leon J. Radziemski, Richard W. Solarz, Jeffrey A. Paisner, Laser Spectroscopy and Its Applications, 2017
Traveling-wave ring-resonator CW dye lasers (pumped by argon or krypton lasers) that efficiently provide tunable single-frequency radiation over the entire visible spectrum from 0.4 to 1 μm are now commercially available [Divens, 1982; Jarrett, 1979] for absorption spectroscopy. The output power of ring dye lasers is typically from a few hundred milliwatts to a few watts, depending on pump laser power and dye efficiency. The root-mean-square (RMS) line widths are 150 kHz and frequency drifts are typically less than 50 MHz/h, which is ideal for high-resolution absorption spectroscopy.
Laser Sources Based on Gaseous, Liquid, or Solid-State Active Media
Published in Helmut H. Telle, Ángel González Ureña, Laser Spectroscopy and Laser Imaging, 2018
Helmut H. Telle, Ángel González Ureña
The typical characteristics of a dye gain medium may be summarized as follows. Firstly, in general, dyes exhibit a broad gain bandwidth, which permits wide wavelength tunability on the one hand and ultrashort-pulse generation (via mode locking) on the other hand. Secondly, the gain per unit length for most dyes is rather high, of the order 103 cm−1, which means that for nanosecond-pulse excitation with high pulse energy, gain saturation is easily encountered and thus oscillator–amplifier chains are required. Thirdly, for common laser pumping, be it CW or pulsed, high conversion efficiency can be reached, typically in the range 10–30% (see the example in Figure 4.8). As the figure demonstrates, the absorption/excitation wavelength is shorter than the emission wavelength; depending on the dye’s absorption spectrum, excitation is afforded for short-wavelength laser dyes by pump lasers in the UV and violet (like excimer lasers, third harmonic Nd:YAG or Ar/Kr ion lasers) or the blue-green (like second harmonic Nd:YAG or Ar ion lasers). Finally, it should be stressed that many laser dyes and some of the solvents are poisonous and/or carcinogenic. Hence, one should be careful to avoid exposure of the skin to dye solutions. A particularly hazardous solvent is dimethylsulfoxide (DMSO); this is sometimes used for cyanide dyes (many near-IR dyes), and its particular hazardous action is that it greatly accelerates the transport of dyes into the skin. Therefore, it is not surprising, for these hazard reasons alone, that dye lasers are more and more being replaced by other types of tunable lasers, which in addition offer the advantage of lower maintenance (note that many laser dyes quickly deteriorate due to photochemical reactions, and thus their efficiency decreases rapidly as a consequence).
Development and Application of Molecular Tagging Velocimetry for Gas Flows in Thermal Hydraulics
Published in Nuclear Technology, 2019
Matthieu A. André, Ross A. Burns, Paul M. Danehy, Seth R. Cadell, Brian G. Woods, Philippe M. Bardet
A 193-nm beam is produced with an ArF excimer laser, while 355 nm is obtained from a frequency tripled Nd:YAG laser. The other wavelengths are obtained with tunable lasers, such as tunable dye lasers or optical parametric oscillators. This is covered in Sec. II.B. Note that other read laser wavelengths, corresponding to other vibrational transitions, can be used for these tracers. Those reported in Table I are the most efficient and widely used. Of the five seed gases listed in Table I, H2O and N2O have been extensively characterized by us, and their behaviors are reported in detail in Secs. II.A.2 through II.A.4.