One example includes an optical transmitter system. The system includes a waveguide to receive and propagate an optical signal. The system also includes a ring modulation system comprising a ring resonator that is optically coupled to the waveguide and is to resonate a given wavelength of the optical signal in response to an input data signal that is provided to a modulation amplifier to provide carrier injection to change a refractive index of the ring resonator to resonate the given wavelength of the optical signal to modulate the optical signal. The system further includes a tuning controller associated with the ring modulation system. The tuning controller can implement iterative feedback tuning of the ring modulation system based on a relative amplitude of an optical intensity of the given wavelength in the ring resonator and a variable reference amplitude to substantially stabilize the ring resonator with respect to the given wavelength.