Multiple-prism Grating Laser Oscillator
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Multiple-prism grating laser oscillators, F. J. Duarte, Narrow-linewidth pulsed dye laser oscillators, in ''Dye Laser Principles'' (Academic, New York, 1990) Chapter 4. or MPG laser oscillators, use multiple-prism beam expansion to illuminate a diffraction grating mounted either in
Littrow configuration Littrow may refer to: *Joseph Johann von Littrow (1781-1840), Austrian astronomer ** Littrow projection, a map projection invented by Joseph Johann Littrow, also called the Weir Azimuth diagram ** Littrow (crater), a lunar crater named for astronom ...
or grazing-incidence configuration. Originally, these narrow-linewidth tunable dispersive oscillators were introduced as multiple-prism Littrow (MPL) grating oscillators, or hybrid multiple-prism near-grazing-incidence (HMPGI) grating cavities, in organic
dye laser A dye laser is a laser that uses an organic dye as the lasing medium, usually as a liquid solution. Compared to gases and most solid state lasing media, a dye can usually be used for a much wider range of wavelengths, often spanning 50 to 100 ...
s. However, these designs were quickly adopted for other types of lasers such as
gas laser A gas laser is a laser in which an electric current is discharged through a gas to produce coherent light. The gas laser was the first continuous-light laser and the first laser to operate on the principle of converting electrical energy to a lase ...
s,
diode laser The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with e ...
s, and more recently
fiber laser A fiber laser (or fibre laser in British English) is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and holmium. They are re ...
s.


Excitation

Multiple-prism grating laser oscillators can be excited either electrically, as in the case of gas lasers and semiconductor lasers,F. J. Duarte, ''Tunable Laser Optics'', 2nd Ed. (CRC, New York, 2015)
or optically, as in the case of crystalline lasers and organic dye lasers. In the case of optical excitation it is often necessary to match the polarization of the excitation laser to the polarization preference of the multiple-prism grating oscillator. This can be done using a
polarization rotator A polarization rotator is an optical device that rotates the polarization axis of a linearly polarized light beam by an angle of choice. Such devices can be based on the Faraday effect, on birefringence, or on total internal reflection.F. J. Du ...
thus improving the laser conversion efficiency.


Linewidth performance

The
multiple-prism dispersion theory The first description of multiple-prism arrays, and multiple-prism dispersion, was given by Newton in his book ''Opticks''. Prism pair expanders were introduced by Brewster in 1813. A modern mathematical description of the single-prism dispersion ...
is applied to design these beam expanders either in additive configuration, thus adding or subtracting their dispersion to the dispersion of the grating, or in compensating configuration (yielding zero dispersion at a design wavelength) thus allowing the diffraction grating to control the tuning characteristics of the laser cavity. Under those conditions, that is, zero dispersion from the multiple-prism beam expander, the single-pass laser linewidth is given by : \Delta\lambda \approx \Delta \theta \left(M \right)^ where \Delta \theta is the beam divergence and ''M'' is the beam magnification provided by the beam expander that multiplies the angular dispersion provided by the diffraction grating. In the case of multiple-prism beam expanders this factor can be as high as 100–200. When the dispersion of the multiple-prism expander is not equal to zero, then the single-pass linewidth is given by : \Delta\lambda \approx \Delta \theta \left(M + \right)^ where the first differential refers to the angular dispersion from the grating and the second differential refers to the overall dispersion from the multiple-prism beam expander. Optimized solid-state multiple-prism grating laser oscillators have been shown, by Duarte, to generate pulsed single-longitudinal-mode emission limited only by
Heisenberg's uncertainty principle In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the accuracy with which the values for certain pairs of physi ...
.F. J. Duarte, Multiple-prism grating solid-state dye laser oscillator: optimized architecture, ''Appl. Opt.'' 38, 6347-6349 (1999). The laser linewidth in these experiments is reported as \Delta \nu ≈ 350 MHz (or \Delta \lambda ≈ 0.0004 nm at 590 nm) in pulses ~ 3 ns wide, at power levels in the kW regime.


Applications

Applications of these tunable narrow-linewidth lasers include: * Coherent anti-Stokes Raman spectroscopy and combustion diagnostics *
LIDAR Lidar (, also LIDAR, or LiDAR; sometimes LADAR) is a method for determining ranges (variable distance) by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. It can also be ...
* Laser
spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...
*
Atomic vapor laser isotope separation Atomic vapor laser isotope separation, or AVLIS, is a method by which specially tuned lasers are used to separate isotopes of uranium using selective ionization of hyperfine transitions. A similar technology, using molecules instead of atoms, is ...
A. Sugiyama, T. Nakayama, M. Kato, Y. Maruyama, T. Arisawa, Characteristics of a pressure-tuned single-mode dye laser oscillator pumped by a copper vapor oscillator, ''Opt. Eng.'' 35, 1093-1097 (1996).


See also

* Dye lasers *
Solid state dye lasers Solid-state dye lasers (SSDL) were introduced in 1967 by Soffer and McFarland. In these solid-state lasers, the gain medium is a laser dye-doped organic matrix such as poly(methyl methacrylate) (PMMA), rather than a liquid solution of the dye. An ...
*
Laser cavity An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors or other optical elements that forms a cavity resonator for light waves. Optical cavities are a major component of lasers, surrounding the gain medium and provid ...
* Laser linewidth *
Multiple-prism dispersion theory The first description of multiple-prism arrays, and multiple-prism dispersion, was given by Newton in his book ''Opticks''. Prism pair expanders were introduced by Brewster in 1813. A modern mathematical description of the single-prism dispersion ...
*
Polarization rotator A polarization rotator is an optical device that rotates the polarization axis of a linearly polarized light beam by an angle of choice. Such devices can be based on the Faraday effect, on birefringence, or on total internal reflection.F. J. Du ...
*
Tunable laser A tunable laser is a laser whose wavelength of operation can be altered in a controlled manner. While all laser gain media allow small shifts in output wavelength, only a few types of lasers allow continuous tuning over a significant wavelength ra ...
s


References


External links


Diagrams of MPG laser oscillators
{{Lasers Quantum optics Prisms (optics) Laser types