Optoelectronic Oscillators Using Direct-Modulated Semiconductor Lasers Under Strong Optical Injection

In this paper, optoelectronic oscillators (OEOs) are demonstrated by using direct-modulated edge-emitting lasers under strong optical injection. The optically injection-locked OEO (OIL-OEO) enables a stable optoelectronic oscillation by converting an optical signal to an electrical signal through a long optical fiber loop. Low RF threshold gain of 7 dB for loop oscillation is attained by utilizing the cavity resonance amplification of an injection-locked semiconductor laser. We investigated both the open- and closed-loop characteristics of the OIL-OEO link by varying the injection locking parameters. Using this novel technique with optimized locking parameters, a 20-GHz RF signal with a phase noise of -123 dBc/Hz is successfully achieved without sophisticated frequency or temperature stabilization.