Monoclinic double tungstate waveguide amplifiers and microlasers

The rare-earth (RE) ion doped monoclinic potassium double tungstates KY(WO₄)₂, KGd(WO₄)₂, and KLu(WO₄)₂ are emerging as very interesting gain materials for the fabrication of waveguide amplifiers and microlasers for future integrated optical devices. The very large transition cross-sections of RE ions doped into these materials provide large gain per unit length, which, together with the large refractive indices, make these materials very promising for on-chip integrated applications. An overview of the latest advances on waveguide amplifiers and microlasers in potassium double tungstates will be presented including different waveguide microfabrication techniques and various examples of recent applications, such as waveguide amplifiers with extremely high gain (~1000 dB/cm), on-chip waveguide lasers with integrated gratings, and waveguide lasers with high output power (>;l400 mW), low quantum defect (0.7%), and broad tunability.