Femtosecond-laser-written low-loss multiscan waveguides in fused silica

We report low-loss multiscan waveguides fabricated in fused silica using femtosecond-laser-writing technology. The multiscan principle allows the writing regime to be tailored to excel at key features of any integrated photonic platform: coupling losses and propagation losses. We optimized the writing parameters for different sizes of square-shaped waveguides and reached the mode overlap value with a standard single-mode optical fiber of above 98.8% and demonstrated very low coupling losses of 0.2 dB/facet on average. Propagation losses in the fabricated waveguides amounted to 0.07 dB/cm. We applied the developed recipe to the fabrication of a fiber-coupled 25-channel interferometer with total insertion losses below 1 dB. The findings of this work are of interest for broad range of applications and in particular for optical information processing and quantum photonics. locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon Physics Subject Headings (PhySH)Integrated opticsDevice fabricationNanostructuresNanotechnologyOptical fibersWaveguide arraysFemtosecond laser irradiationSample preparation