Low jitter microwave pulse train generation based on an optoelectronic oscillator

Area of Science:

• Photonics and Optics
• Electrical Engineering
• Signal Processing

Background:

• Optoelectronic oscillators (OEOs) are crucial for generating stable microwave signals.
• Achieving ultra-short optical pulse trains with low time jitter is essential for high-speed optical communications and signal processing.
• Existing methods often face limitations in pulse quality and jitter performance.

Purpose of the Study:

• To demonstrate a new approach for generating ultra-short optical pulse trains with significantly reduced time jitter.
• To leverage the unique properties of a dual-loop optoelectronic oscillator (OEO) for frequency comb generation and pulse compression.
• To experimentally validate the performance of the proposed OEO-based pulse generation technique.

Main Methods:

• Utilizing a dual-loop OEO architecture with distinct long and short feedback loops, incorporating phase modulators (PM) and Mach-Zehnder modulators (MZM).
• Exploiting the Vernier effect for mode selection to generate a single-frequency microwave carrier with multiple optical sidebands, forming an optical comb.
• Employing dispersion compensating fiber (DCF) to adjust phase relationships between optical sidebands for stable pulse train generation.

Main Results:

• Successfully generated an optical pulse train with a repetition frequency of 2.023 GHz and a pulse width of 40 picoseconds (ps).
• Measured single-sideband (SSB) phase noise of -118 dBc/Hz at a 10-kHz offset, corresponding to a time jitter of 391.2 femtoseconds (fs).
• Indicated potential for further jitter reduction to the tens of femtoseconds range with active cavity stabilization.

Conclusions:

• The proposed dual-loop OEO approach effectively generates ultra-short optical pulse trains with low time jitter.
• The Vernier effect and precise phase control are key to achieving high-quality pulse trains.
• This technique offers a promising solution for applications demanding high-performance optical pulse generation.