Fourier-transform external cavity lasers

We explore the potential of a new laser resonator design that uses an intracavity Fourier transformation and allows for multi-color operation, gain extension and intracavity second harmonic generation (SHG). First, purely electronically controlled wavelength tuning is demonstrated using liquid crystal displays (LCDs) and digital mirror devices. Moreover, the new design can be applied to different lasers as shown on the examples of a laser diode and a Thulium-doped fiber laser in the mid-infrared. Furthermore, we demonstrate the simultaneous control of multiple gain media within one single external cavity. In addition, tunable emission in the 490 nm range is obtained using intracavity SHG with one single control parameter. Finally, we unambiguously prove simultaneous multi-wavelength operation with variable wavelength spacings and apply it to the generation of THz difference frequencies.