Scalable Phase Trimming of Non-Hydrogen-Loaded Planar Lightwave Circuits with a Krypton Fluoride Laser

The induction of permanent refractive index changes in silica-on-silicon planar lightwave circuits with krypton fluoride excimer laser pulses and no hydrogen loading is demonstrated and studied. Upon locally irradiating asymmetrical Mach-Zehnder interferometers with an accumulated fluence of 40 kJ/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and subsequent annealing, reproducible wavelength shifts over 30 nm in the interferometer spectral response are achieved. The proposed phase-trimming protocol could maximize the performance and yield of mass-produced photonic chips and thus enhance their large-scale deployability with benefits in many areas from instrumentation to LiDAR.