"Waveguide networks in three-dimensional architecture were written by the femtosecond laser with a repetition rate of 1 MHz, a central wavelength of 513 nm, a pulse duration of 290 fs, and a pulse energy of 190 nJ. Before radiating into the borosilicate substrate at a depth of 170 μm, the laser beam was shaped by a cylindrical lens and then focused by a 100× objective with a numerical aperture of 0.7. During the fabrication, the translational stage moved in x, y, and z directions according to the user-defined program at a constant speed of 15 mm/s. The careful measurements and characterization on the geometric parameter dependence of the three types of junction, such as coupling length, coupling distance, decoupling distance, and curvature, were taken to optimize the performance to form the standard elements."
Photonic chip fabrication
"Waveguide networks in three-dimensional architecture were written by the femtosecond laser with a repetition rate of 1 MHz, a central wavelength of 513 nm, a pulse duration of 290 fs, and a pulse energy of 190 nJ. Before radiating into the borosilicate substrate at a depth of 170 μm, the laser beam was shaped by a cylindrical lens and then focused by a 100× objective with a numerical aperture of 0.7. During the fabrication, the translational stage moved in x, y, and z directions according to the user-defined program at a constant speed of 15 mm/s. The careful measurements and characterization on the geometric parameter dependence of the three types of junction, such as coupling length, coupling distance, decoupling distance, and curvature, were taken to optimize the performance to form the standard elements."