Tunable lasers

The principal techniques for obtaining tunable laser radiation from the near-ultraviolet to the infrared region of the spectrum are reviewed both from the point of view of their fundamental physical principles and their state-of-the-art device operation and technology. An attempt has been made to give a comprehensive account of the most recent applications of these techniques. The term tunable lasers is arbitrarily defined to mean lasers which are broadly tunable over 100 cm^-1 or more, and includes dye lasers, optical parametric oscillators, spin-flip Raman lasers and semiconductor diode lasers. The tunable lasers are compared and contrasted in terms of tuning ranges, powers, linewidths and stability; it is concluded that where the systems overlap they are complementary, with no one system being better in every respect for all applications.