Progress in Tunable Lasers

No doubt, tunable lasers play an important role in scientific investigations and in technical applications. Therefore we find a strong interest to improve tunable lasers and to extend their frequency range: Dye lasers today have excellent properties as tunable systems but their operation area is limited to the visible region and the close vicinity. Within the last four to five years there was a strong development of color center lasers and they became the near infrared counterpart to the dye lasers. The active material in dye and color center lasers — dyes and color center crystals — are no natural products. However dyes were already available in large numbers, whereas each new color center crystal suitable as laser material had to be developed, making the progress in color center lasers so tedious. Nevertheless the state of the art of color center lasers was continuously improved. In the first part of this lecture recent improvements that have been achieved by my coworker G. Litfin will be reported.