Ultra low-loss waveguides of 0.12 dB/cm directly written in pure silica glass by femtosecond laser pulses

Three-Dimensional Waveguide Interconnection in Planar Lightwave Circuits by Direct Writing with Femtosecond Laser

“…[1][2][3] Specifically, this technique has advantage to other optical device fabrication methods, because it enables us to make three-dimensional (3D) optical circuits. Some 3D optical circuits have already reported, such as 3D splitter, 4) and 3D ring oscillator. 5) Although the laser-written waveguide fabrication is effective for achieving the 3D optical circuits, it takes a long time to make complex optical circuits.…”

“…From this estimation, we found that the excess loss caused by the position misalignment of the written waveguide was less than 0.4 dB/point. Since the loss caused by the MFD mismatch can be suppressed to below 0.1 dB, 4) further loss reduction can be expected.…”