Tunable Intracavity Coherent Up-conversion with Giant Nonlinearity in a Polar Fluidic Medium

We demonstrate a novel microcavity-based photon up-conversion using second harmonic generation (SHG) from a polar nematic fluid media doped with a laser dye. The present idea is based on coherent light generation via simultaneous frequency doubling and stimulated emission (lasing) inside a microcavity. The polar nematic fluid equips very high even-order optical nonlinearity due to the polar symmetry and large dipole moment along the molecular long axis. At the same time, its inherent fluidic nature allows us to easily functionalize the media just by doping, in the present case, with an emissive laser dye. Our demonstrated system exhibits a giant nonlinear optical response to input light, while enabling spectral narrowing and multiple-signal output of up-converted light, that is not attainable though the simple SH-conversion of input light. Furthermore, susceptibility of the liquid crystal offers dynamic modulation capabilities under external stimulus, such as signal switching with electric field application or wavelength tuning through temperature variation. Such a brand-new type of simple coherent flexible up-conversion system must be promising as a new principle for easy-accessible and down-scalable wavelength conversion devices.