An example optical device, such as a Mach-Zehnder interferometer (MZI) is presented. The MZI includes a plurality of optical waveguide arms. At least one of the plurality of optical waveguide arms comprises a control gate, an optical waveguide, and a floating gate positioned between the control gate and the optical waveguide and electrically isolated from the optical waveguide and the control gate. The control gate receives a control voltage. The application of the control voltage to the control gate causes charges to accumulate in the floating gate resulting in a non-volatile change in an operating wavelength of the MZI.