Infrared tunable laser

A tunable laser apparatus is reported with a first wavelength selective reflector and a second wavelength selective reflector forming one end of an optical cavity, and a third wavelength selective reflector forming the other end of an optical cavity. A first lasable dye solution develops radiation of a wavelength selected by the first reflector and a second lasable dye solution develops radiation of a wavelength selected by the second reflector and a non-linear mixing crystal disposed within the optical cavity. The selected radiation is passed through the nonlinear mixing crystal causing it to develop radiation of a third wavelength which is transmitted out of the optical cavity through the third reflector.