Two-Wavelength, Passive Self-Injection-Controlled Operation of Diode-Pumped cw YbDoped Crystal Lasers

We demonstrate and investigate a peculiar mode of cw Yb3 +-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original twochannel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3 + lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3 +:GGG laser but similar results are also obtained with a Yb3 +:YAG laser. The laser operates in the 1023 -1033-nm (1030 -1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.