High-power tunable two-color VECSEL for on-demand wavelength generation

High power, tunable two color lasers are highly suitable for the new wavelengths generation thanks to various nonlinear conversion phenomena. Vertical external cavity surface emitting lasers (VECSELs) are of special interest due to the access to the high intracavity circulating power and wavelength control. We report a novel VECSEL cavity design, which can deliver high power, tunable two color emission. The VECSEL setup is based on a two-chip T-shape cavity configuration which utilizes a polarizing beam splitter to combine two VECSEL cavities. This allows for two-color orthogonally polarized high-power collinear outputs. The two color emission of this kind is ideal for type II nonlinear frequency conversion. A high-Q folded T-cavity is utilized to achieve the combined beams circulating power in excess of 175 W. Intracavity birefringent filters are used to facilitate tunability and wavelength separation between two colors. A configuration of this type is used for high power intracavity type II sum frequency generation, which resulted in tunable blue emission with above 750 mW output, and in the second case a tunable green emission with more than 1.4 W output was obtained. A signal around 1 THz was achieved through type II difference frequency generation in tilted periodically poled lithium niobate. Lastly, a silver thiogallate was utilized to generate mid-IR wavelength around 5.36 μm through type II difference frequency generation.