Laser-written optical-path redirected waveguide device for optical back-plane interconnects

A novel optical-path redirected three-dimensional waveguide device for optical back-plane interconnects is demonstrated. To fabricate an optical waveguide device, a laser-written technique using focused irradiation of visible femtosecond pulses is employed. In this waveguide device, single-stroke drawing is applied for low-cost fabrication. To redirect the optical path, a planar reflective mirror was adopted. Since the focus of the laser was shifted successively while drawing cores in glass substrate, multichannel optical cores were continuously written up to the surface component. By having this structure, back-plane interconnects can be integrated more densely, and an optical back-plane board can be coupled to a daughter-board directly without any microlenses. Furthermore, all cores have the same length, so this device potentially suppresses the modulation skew caused by the difference of optical-path lengths. We present the fabrication and the test results of a glass-based waveguide device for optical-path redirection.