An apparatus 100 that comprises a planar electro-optic modulator 110 being located on a substrate 105 and including a waveguide 115 and electrical contacts 120. The waveguide that includes first and second substantially straight segments 122, and a curved segment 126 that serially end-connects the first and second substantially straight segments such that light 130 travels in a substantially anti-parallel manner in the first and second substantially straight segments. The electrical contacts being located adjacent the first and second substantially straight segments and being connected to produce constructively adding phase modulations on an optical carrier passing through the segments.