Instantaneous frequency measurement system based on quantum dash mode-locked laser

Area of Science:

• Photonics
• Optical Engineering
• Signal Processing

Background:

• Instantaneous frequency measurement (IFM) is crucial for various applications.
• Existing IFM systems face limitations in speed and accuracy.
• Microwave photonic (MWP) systems offer potential for high-performance IFM.

Purpose of the Study:

• To develop and experimentally validate a novel MWP filter-based system for instantaneous frequency measurement.
• To demonstrate the system's capability using a quantum dash mode-locked laser as an optical frequency comb source.
• To analyze the system's performance in terms of measurement range and accuracy.

Main Methods:

• Utilized a quantum dash mode-locked laser to generate a stable optical frequency comb with up to 41 flat comb lines.
• Implemented a real-time feedback loop for precise comb shaping.
• Designed and tested a set of MWP filters with linear frequency responses (linear and dB units).

Main Results:

• Experimentally demonstrated MWP filters with linear frequency responses.
• Achieved a maximum measurement frequency of up to 20 GHz, limited by instrumentation.
• Reduced root-mean-square error from 51-66 MHz (one filter) to 42.2 MHz (linear unit) and 30.7 MHz (dB unit) using two filters.

Conclusions:

• The developed MWP filter system enables accurate instantaneous frequency measurement.
• The system shows improved accuracy with the use of two MWP filters.
• This technology has potential for advanced signal processing and measurement applications.