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A dye laser is a laser which 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 nanometers or more. The wide bandwidth makes them particularly suitable for tunable lasers and pulsed lasers. The dye rhodamine 6G, for example, can be tuned from 635 nm (orangish-red) to 560 nm (greenish-yellow), and produce pulses as short as 16 femtoseconds.〔''Dye Laser Principles: With Applications'' by Frank J. Duarte, Lloyd W. Hillman -- Academic Press 1990 Page 42〕 Moreover, the dye can be replaced by another type in order to generate an even broader range of wavelengths with the same laser, from the near-infrared to the near-ultraviolet, although this usually requires replacing other optical components in the laser as well. Dye lasers were independently discovered by P. P. Sorokin and F. P. Schäfer (and colleagues) in 1966.〔F. P. Schäfer (Ed.), ''Dye Lasers'' (Springer-Verlag, Berlin, 1990).〕〔F. J. Duarte and L. W. Hillman (Eds.), ''Dye Laser Principles'' (Academic, New York, 1990).〕 In addition to the usual liquid state, dye lasers are also available as solid state dye lasers (SSDL). SSDL use dye-doped organic matrices as gain medium. ==Construction== A dye laser consists of an organic dye mixed with a solvent, which may be circulated through a dye cell, or streamed through open air using a dye jet. A high energy source of light is needed to 'pump' the liquid beyond its lasing threshold. A fast discharge flashlamp or an external laser is usually used for this purpose. Mirrors are also needed to oscillate the light produced by the dye’s fluorescence, which is amplified with each pass through the liquid. The output mirror is normally around 80% reflective, while all other mirrors are usually more than 99.9% reflective. The dye solution is usually circulated at high speeds, to help avoid triplet absorption and to decrease degradation of the dye. A prism or diffraction grating is usually mounted in the beam path, to allow tuning of the beam. Because the liquid medium of a dye laser can fit any shape, there are a multitude of different configurations that can be used. A Fabry–Pérot laser cavity is usually used for flashlamp pumped lasers, which consists of two mirrors, which may be flat or curved, mounted parallel to each other with the laser medium in between. The dye cell is usually side-pumped, with one or more flashlamps running parallel to the dye cell in a reflector cavity. The reflector cavity is often water cooled, to prevent thermal shock in the dye caused by the large amounts of near-infrared radiation which the flashlamp produces. Axial pumped lasers have a hollow, annular-shaped flashlamp that surrounds the dye cell, which has lower inductance for a shorter flash, and improved transfer efficiency. Coaxial pumped lasers have an annular dye cell that surrounds the flash lamp, for even better transfer efficiency, but have a lower gain due to diffraction losses. Flash pumped lasers can be used only for pulsed output applications.〔Design and Analysis of Flashlamp Systems for Pumping Organic Dye Lasers – J. F. Holzrichter and A. L. Schawlow. Annals of the New York Academy of Sciences〕〔Simmer-Enhanced Flashlamp Pumped Dye Laser – T.K. Yee, B. Fan and T.K. Gustafson. Applied Optics – Vol. 18, No. 8〕〔(General Xenon Flash and Strobe Design Guidelines )〕 A ring laser design is often chosen for continuous operation, although a Fabry–Pérot design is sometimes used. In a ring laser, the mirrors of the laser are positioned to allow the beam to travel in a circular path. The dye cell, or cuvette, is usually very small. Sometimes a dye jet is used to help avoid reflection losses. The dye is usually pumped with an external laser, such as a nitrogen, excimer, or frequency doubled Nd:YAG laser. The liquid is circulated at very high speeds, to prevent triplet absorption from cutting off the beam.〔(Sam's Laser FAQ - Home-Built Dye Laser )〕 Unlike Fabry–Pérot cavities, a ring laser does not generate standing waves which cause spatial hole burning, a phenomenon where energy becomes trapped in unused portions of the medium between the crests of the wave. This leads to a better gain from the lasing medium.〔(Encyclopedia of Laser Physics and Technology - spatial hole burning, SHB, laser, single-frequency operation )〕〔''Laser fundamentals'' by William T. Silfvast – Cambridge University Press 1996 Page 397-399〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「dye laser」の詳細全文を読む スポンサード リンク
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