Low bending loss waveguide opens the avenue to downsizing of 3-D photonic integrated circuits

Femtosecond laser direct writing is a promising technology for the fabrication of photonic integrated chips mainly due to its intrinsic capability of three-dimensional (3-D) prototyping in transparent substrates. Currently, the difficulty in inducing large refractive index changes smoothly distributed in the laser-irradiated regions is the major obstacle for producing compact photonic integrated circuits (PICs). Recently, researchers in China proposed a solution to suppress the bend loss of the waveguide at small radii of curvatures by more than one order of magnitude, opening a new avenue to downsizing of 3-D photonic integrated circuits. Their work, titled “Suppression of bend loss in writing of three-dimensional optical waveguides with femtosecond laser pulses,” was published in Science China Physics, Mechanics & Astronomy.