Ultrafast and High Extinction Ratio 1×4 Electro-Optical Switch Based on Cascaded Dual-Output MZI

Abstract

We propose and fabricate an ultrafast and high extinction ratio 1×4 optical switch based on a cascade, dual-output Mach-Zehnder interferometer (MZI) on the lithium niobate platform. The optical switch consists of cascaded, identical, dual-output MZI structures, and each of them includes a Y-branch waveguide, two parallel interference arms (electrode action area), and a 3 dB directional coupler. Four output optical paths can be switched through three groups of electrode hierarchical modulation. The test results of the fabricated device show that the insertion loss of each port is less than 7.1 dB and that the maximum extinction ratio is higher than 39.3 dB. The optical switch can achieve a high extinction ratio greater than 20 dB within the 50 nm wavelength range. The measured half-wave voltage is less than 4.13 V, and the minimum switching rise and fall times reach 125 ps and 250 ps, respectively. This result shows that the proposed and fabricated 1×4 integrated optical switch on a lithium niobate platform has the advantages of a fast response rate, high extinction ratio, and low switching voltage.Index Terms-Dual-output MZI, 1×4 electro-optical switch, ultrafast and high extinction ratio, optical waveguide. I. INTRODUCTIONPTICAL switches have displayed many advantages, such as high speed, transparency, and low power consumption, in all-optical internet applications and have been widely employed in optical communication packet switching [1], optical computing [2], and quantum key distribution [3]. With the increasing requirements for communication quality and speed, higher requirements are proposed for the extinction ratio [4,5], switching speed [6], multiple ports [7], and insertion loss [8] of optical switches. Microelectromechanical system (MEMS) optical switching is relatively mature and can be employed for large array network architecture with good extinction ratio performance but limited speed (~ms) [9][10][11]. Waveguide optical switching uses the electro-optic effect, acousto-optic effect, and thermo-optic effect to realize the optical switch function. The electro-optic switch has the fastest response speed (~ns) and low heat, which is suitable for small signal optical communication [12,13]. Waveguide optical switches composed of various Planar Manuscript