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

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.