Apparatus and methods that utilize dual, tunable elements to provide for selective wavelength tuning of a light beam. The apparatus comprises a first tunable wavelength selection element positioned in a light beam and having a first adjustable free spectral range, a second tunable wavelength selection...http://www.google.de/patents/US20020172239?utm_source=gb-gplus-sharePatent US20020172239 - Tunable external cavity laser
