Supercontinuum Generation in Lithium Niobate Ridge Waveguides Fabricated by Proton Exchange and Ion Beam Enhanced Etching

We report on the fabrication of the 10-mm-long lithium niobate ridge waveguide and its supercontinuum generation at near-visible wavelengths (around 800 nm). The waveguides are fabricated by a combination of MeV copper ion implantation followed by wet etching in a proton exchanged lithium niobate planar waveguide. Using a mode-locked Ti:sapphire laser with a central wavelength of 800 nm, the generated broadest supercontinuum through the ridge waveguides spans 302 nm (at -30 dB points), from 693 to 995 nm. Temporal coherence properties of the supercontinuum are experimentally studied by a Michelson interferometer and the coherence length of the broadest supercontinuum is measured to be 5.2 μm. Our results offer potential for a compact and integrated supercontinuum source for applications including bio-imaging, spectroscopy and optical communication.