One example includes a laser system. The system can include a first electrode to transmit first electrical carriers into an active region via a first waveguide region in response to a current signal. The system also includes a second electrode to transmit second electrical carriers into the active region via a second waveguide region in response to the current signal. The first and second electrical carriers can be combined in the active region to emit photons to generate an optical signal. The system further includes a third electrode responsive to a signal to affect a concentration of third electrical carriers in a device layer located proximal to the second waveguide region to modulate an optical characteristic of the optical signal.