Abstract: A fully integrated photonic IC for optical clock generation using no electronic current modulation. A first and second laser stripes are joined by a Kerr effect non-linear directional coupler, NLDC. The first stripe is pumped with a DC current for laser generation, and the second stripe has a reflector at an end facet for generation of mode selective optical feedback. The DC current generates relaxation oscillation in both stripes and the Kerr effect of the NLDC causes the electric fields in both stripe to interact constructively so as to shift the relaxation oscillation to undamped oscillation. The optical clock generator is tuned by varying the applied DC current.