A programmable photonic circuit is provided that includes a dimmable optical coupler, an optical phase shifter, and a control unit. The first and second waveguides are disposed in first portions corresponding to each other in a dimmable coupler, the dimmable coupler including a first actuator to adjust an optical coupling efficiency of an optical signal between the first and second waveguides. One of the first and second waveguides and the disturbing waveguide are disposed in a second portion corresponding to each other in the optical phase shifter, and the optical phase shifter includes a second actuator, a perturbation waveguide is provided to vary a phase of an optical signal passing through the one waveguide by varying an effective refractive index of an optical mode of the one waveguide according to a gap between the one waveguide and the perturbation waveguide. The control unit controls drive signals applied to the first and second actuators.
