Controlled Wavelength Tuning of Single-Mode Lasers

5 Controlled Wavelength Tuning of Single-Mode Lasers 

Although fixed-wavelength lasers have proved their importance for many spectroscopic apphcahons (Vol.2, Sect. 1.7 and Vol. 2, Chaps. 3, 5, and 8), it was the development of continuously tunable lasers that really revolutionized the whole field of spectroscopy. This is demonstrated by the avalanche of publications on tunable lasers and their apphcations (e.g., [5.96]). We shall therefore treat in this sechon some basic techniques for controlled tuning of 

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Controlled Wavelength Tuning of Single-Mode Lasers ------------------6--------------... 

We shall describe the experimental techniques that are necessary for achieving optimal results in spectroscopic applications. These techniques comprise mode selection in lasers, wavelength and intensity stabilization of single-mode lasers, and experimental realizations of controlled wavele7 gth tuning. Furthermore we briefly discuss the interesting question of why a lower limit exists for the laser linewidth. At the end of this chapter some methods of relative and absolute frequency measurements in the optical region will be presented. 

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