A Simple Optoelectronic Oscillator with All-optical Gain Based on the Dual-frequency Integrated Semiconductor Laser

Abstract

A novel photonic method to generate high-frequency microwave signals based on the all-optical gain OEO is proposed in this paper. The core device is the monolithically integrated mutually injected laser, in which two DFB laser sections are simultaneously fabricated on one chip. By tuning the appropriate control currents, the monolithically integrated mutually injected laser would oscillate on two different optical modes and thus, it can be seen as one natural dual-frequency laser. Attributing to the combined effects of the photon-to-photon resonance (PPR) phenomenon in the dual-mode laser as well as the sideband injection locking amplification (SAIL) influence in the close OEO configuration, the modulation response of the laser module would be correspondingly changed, and in theory, the modulation response peak of the relaxation resonance frequency (RRF) can be increased infinitely due to the infinite frequency interval between the oscillating optical modes, leading to a widely tunable microwave photonic filter (MPF). In addition, the 3-dB bandwidth is also limited, indicating a high Q value. The gain is provided by optical means through one erbium doped optical amplifier (EDFA). On the basis of this principle, the highspeed external electric-optical modulator (EOM), huge-frequency electrical bandpass filters (EBPFs) with narrow 3-dB bandwidth as well as multi-stage electrical amplifiers (EAs) can be eliminated once the OEO loop is closed. In the current proof-of-concept experiment, one microwave signal with the SSB phase noise at -105.38 dBc/Hz @10 kHz from the central carrier of 17.2 GHz is realized, indicating an evident performance optimization. Additionally, by making full use of the Reconstruction Equivalent Chirp (REC) technique, the integrated dual-frequency laser can be fabricated easily similar with conventional fabrication process, leading to this system rather compact and a promising candidate for use in high-frequency microwave signals generation.