The output beam from a laser may be modulated using a coupled waveguide modulator that may be endfire coupled to the laser, or integrally formed on a common substrate with the laser, thereby providing a monolithic laser/modulator system that may manufactured using a high-volume semiconductor manufacturing process. The coupled waveguide modulator includes a substrate having a coupler region and an output region. A first waveguide on the substrate is parallel to an optical axis. A second waveguide is formed proximate the first waveguide, is parallel to the optical axis, and is separated from the first waveguide by a coupling distance in at least the coupler region. The second waveguide is nonparallel to the optical axis and separated from the first waveguide by at least the coupling distance in at least part of the output region.