Frequency Stabilization of the Tunable Optoelectronic Oscillator Based on anUltra-High-Q Microring Resonator

As the rapid development of silicon photonics, high-Q silicon microring resonators (MRRs) have been extensively used in the integrated microwave photonic systems. However, one major hurdle to be overcome is that the resonant wavelengths of MRR are highly sensitive to the chip temperature. Herein, a frequency stabilized optoelectronic oscillator (OEO) based on an ultra-high-Q silicon MRR is proposed and experimentally demonstrated. The frequency stabilization is realized by using a home-made feedback control loop based on threshold-detection method to stabilize the resonant wavelengths of the MRR. By using the frequency-stabilization technique, the measured frequency jitter of the MRR based OEO is reduced from 50 MHz to 85 kHz in 10 minutes. The oscillating frequency of the proposed OEO can be also tuned between 0 and 20 GHz. By designing and fabricating the MRR with cascaded multi-mode and single-mode waveguides, the measured Q factor of the fabricated MRR is as high as 1.13 × 10
⁶
. The corresponding phase noise of the microwave signal at 10 kHz offset frequency is -95 dBc/Hz when the microwave signal is 12.23 GHz. During the oscillating frequency tuning, the side-mode suppression ratio (SMSR) remains above 50 dB. The proposed MRR-based OEO with long-term stability has the potential to be monolithically integrated.