ABSTRACT
Today, the field of broadly tunable lasers includes an array of different lasers, which have markedly extended the applicability domain of lasers. In addition to the broadly tunable organic dye lasers, there are broadly tunable semiconductor lasers, optical parametric oscillators (OPOs), tunable fiber lasers, tunable quantum cascade lasers, and free electron lasers (FELs). Also, at this stage, it should be realized that in addition to the class of broadly tunable lasers, there is an additional group of discretely tunable or line-tunable lasers. This latter class of laser, besides being able to shift emission frequency from transition to transition, can also be fine-tuned within the emission spectrum of a given transition.
