A reconfigurable optoelectronic oscillator based on cascaded coherence-controllable recirculating delay lines.

Area of Science:

• Optoelectronics
• Microwave Engineering
• Photonics

Background:

• Optoelectronic oscillators (OEOs) are crucial for generating stable microwave signals.
• Traditional OEOs often rely on electronic filters, which can limit performance.
• Photonic microwave filters (PMFs) offer an alternative for frequency selection in OEOs.

Purpose of the Study:

• To propose and experimentally demonstrate a novel optoelectronic oscillator (OEO).
• To utilize cascaded recirculating delay lines (RDLs) to create infinite impulse response (IIR) photonic microwave filters (PMFs).
• To achieve stable microwave signal generation without electronic filters.

Main Methods:

• Proposed an OEO design employing two cascaded recirculating delay lines (RDLs) as infinite impulse response (IIR) photonic microwave filters (PMFs).
• Utilized an amplified spontaneous emission (ASE) source to prevent self-interference within RDLs.
• Employed RDLs with approximately equal gains to minimize mutual interference.
• Experimentally tuned the lengths of the RDLs to generate microwave signals at different frequencies.

Main Results:

• Successfully demonstrated the proposed OEO design.
• Generated stable microwave signals at frequencies of 194.1 MHz, 648.5 MHz, and 2.99 GHz by adjusting RDL lengths.
• Investigated the phase noise performance of the generated microwave signals.
• Confirmed the potential for generating microwave signals up to tens of GHz using integrated micro-ring devices.

Conclusions:

• The proposed OEO using cascaded RDLs effectively generates stable microwave signals.
• The use of IIR PMFs provides a viable alternative to electronic filters in OEOs.
• This approach holds promise for future high-frequency microwave signal generation, particularly with integrated photonic technologies.