Widely tunable lasers offer discontinuous tuning over wavelength ranges between about one and several hundred nm, increasing with increasing wavelength. Due to the large tuning range these lasers are ideally suited for sensing applications in liquids and solids. Single-mode selection is realized in these devices by coupling two or more resonator sections. A wide tunability is achieved by temperature and current tuning of the segments. 

Widely tunable lasers are realized in all wavelength ranges where distributed feedback lasers are available.

Typical cw room temperature output power specifications are 1 mW at a drive current of 100 mA or less. Maximum output powers of the order of 5 mW can be reached. The tuning speed of the lasers exceeds 100 nm/ms.