Low-loss intersecting grooved waveguides with low Δ for a self-holding optical matrix switch

Our method using low Δ waveguides decreases the insertion loss of intersecting optical waveguides with grooves. Theoretical analysis by the beam propagation method or the plane wave expansion method shows the benefit of decreasing the insertion loss. Experimental measurements on a trial matrix (21×21) showed that the transmission loss greatly decreased with decreasing Δ. The reflection loss was less sensitive to the positional deviation of the groove than that of conventional Δ waveguides. The experimental results were used to calculate the total insertion loss. It decreased from 5.72 to 3.28 dB, when Δ decreased from 0.31 to 0.15% for a matrix scale of 50×50