Ultrawide and tunable self-oscillating optical frequency comb generator based on an optoelectronic oscillator

A new mechanism for ultra-wide and tunable self-oscillating optical frequency comb (OFC) based on a novel frequency tunable optoelectronic oscillator (OEO) is proposed using cascaded configuration of optical phase-modulator (PM) and electro-absorption-modulator (EAM). The proposed scheme does not require a dedicated RF source to drive the optical-modulators. The OEO is configured by incorporating the self-oscillation loop with cascaded modulators. A high-speed PIN-photodetector (PD) with a dark current of 10nA, bandwidth of 20 GHz, and responsivity of 1A/W in correspondence with an electrical-amplifier (EA), and bandpass Bessel filter (BPBF) is utilized to convert the optical signal into a microwave signal. The PD detected signal is amplified by the EA. The BPBF is used to extract a 10 Mhz bandwidth from the amplified signal with tunable central frequencies. Part of the extracted OEO signal is directly connected to the PM, whereas, a 180-degree phase-shift is added to the signal before transmitting into the EAM. The PM produces similar to 19 carrier frequencies, whereas, the generated tunable carriers by the EAM ranges from 85 to 35carrriers with an overall bandwidth of similar to 1.28THz. The negligible power-fluctuations, good number of generated carriers, and high tone-to-noise-ratio of around 40 dB endorse the applicability of the proposed scheme.

Automated summary

A new mechanism for ultra-wide and tunable self-oscillating optical frequency comb based on a novel frequency tunable optoelectronic oscillator is proposed, utilizing cascaded optical phase-modulator and electro-absorption-modulator configurations. The scheme does not require a dedicated RF source to drive the optical modulators and achieves a high tone-to-noise ratio of around 40 dB with negligible power fluctuations. The system utilizes a high-speed PIN-photodetector, electrical-amplifier, and bandpass Bessel filter to convert the optical signal into a microwave signal and extract a tunable central frequency bandwidth of 10 MHz.