Miniaturized directional coupler—type optical switches

Abstract

AbstractOptical switches not only find wide applications, but also are used in a matrix form. Hence, reduction of the single elements is important for improving the integration density and improving the characteristics of the bandwidth and insertion loss. In this paper, a fabrication guideline has been obtained for a miniaturized LiNbO3 directional coupler‐type optical switch. Next, based on the guideline, a device was fabricated, and the relationship of the waveguide spacing S to the coupling length L0 and the phase constant difference Δβ/C was measured by the monitor method using a metal loading. At the wavelength of λ = 1.15 μm, we obtained S = 1.7 μm, L0 = 1.6 mm (previously several millimeters) and Δβ/C = 0 as the minimum. Further, an optical switch with two divided electrodes was fabricated and the switch voltage of V0 = 12 V, extinction ratio of 9.8 dB, and optical insertion loss of 3.6 dB were obtained. Items to be investigated for further improvement are included.