A digital-to-analog converter has a first interface coupled to a second interface through one or more modulation circuits. The circuits include a first coupler connected to the first interface; a first waveguide with a first lead connected to the first coupler, a first end, and a first length running therebetween. The first lead and the first end are coupled by a first switch. The circuits also include: a second coupler connected to the first interface; a second waveguide having a second lead connected to the second coupler, a second end, and a second length running therebetween, the second lead and the second end coupled by a second switch along the second length; and an optical combiner connected to the ends of the waveguides. The second interface is connected to the optical combiner of the modulation circuits. Output from the second interface is an optical signal capable of carrying binary information.