Reconfigurable Three-Mode Converter Based On Cascaded Electro-Optic Long-Period Gratings
Wei Jin, Kin Seng Chiang
Abstract
We propose an optical waveguide switch to realize complete reconfigurable mode conversion for three spatial modes. This device consists of three cascaded long-period grating mode converters of different types integrated along a three-mode lithium-niobate (LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) waveguide, where the gratings can be electro-optically controlled to activate mode conversion independently. We fabricate the device with z-cut LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , which employs graphene electrodes to drive the gratings and an electrode heater to achieve wavelength matching for the three gratings. The half-π voltages of the three gratings in a typical fabricated device, which is 26 mm long and operates at 1545 nm, are 48, 37, and 43 V, respectively. The proposed mode switch could find applications in reconfigurable mode-division-multiplexing communication systems based on few-mode fibers and other areas where programmable mode conversion is required.