High index contrast passive potassium double tungstate waveguides

High-refractive-index-contrast potassium double tungstate waveguides have been experimentally demonstrated. A bulk KY(WO4)2 layer was successfully bonded onto a lower refractive index carrier using a UV curable optical adhesive and polished down to the thickness of 2.4 µm. A set of rib waveguides with ~2 μm width and 0.85 μm slab thickness were fabricated on the thin transferred KY(WO4)2 layer by focused-ion-beam milling. The upper-limit of the propagation losses of the fabricated waveguides is estimated to be 1.5 dB/cm at the wavelength of 1.55 μm using the Fabry-Perot method.