Multimode Waveguide Crossings and Turning Mirror Couplers for PIC

The perturbation is the minimum when the crossing occurs at the self-image location in a low-loss multimode waveguide (MMI). Such waveguides can cross at 90 degrees or 60 degrees at the center with minimal cross talk. One can reflect the incident mode into an intersecting waveguide by introducing an idea reflecting plane. Passive component for λ = 1.41 μm , 1x1/ 2x2 90-degree MMI turning mirror coupler and a single ring resonator with 2x2 MMI turning mirror couplers have been fabricated. The length of MMI turning mirror coupler is only 33% MMI coupler with K=0.15. The circumference in this ring resonator is decreased by 50%. Its FSR is of 82 GHz and a FWHM of 0.24 nm for the drop port.