Precise laser linewidth measurement by feature extraction with short-delay self-homodyne

Area of Science:

• Optics and Photonics
• Laser Physics
• Metrology

Background:

• Accurate laser linewidth measurement is crucial for advanced optical systems.
• Existing methods like self-heterodyne systems can be complex and less precise.
• The coherent power spectrum contains valuable information for linewidth analysis.

Purpose of the Study:

• To develop a novel, high-precision laser linewidth measurement technique.
• To utilize the second peak-valley difference (SPVD) feature of the coherent power spectrum.
• To establish a simpler and more accurate alternative to existing linewidth measurement methods.

Main Methods:

• Development of a short-delay self-homodyne system.
• Modeling the SPVD of the self-homodyne coherent envelope spectrum.
• Theoretical, simulation, and experimental validation of the SPVD-linewidth relationship.
• Comparative analysis with self-heterodyne systems.

Main Results:

• A theoretical and simulated one-to-one correspondence between SPVD, delay length, and laser linewidth was established.
• Experimental verification confirmed the reliability and stability of the proposed method.
• The short-delay self-homodyne method yielded linewidth values closer to the true value than the self-heterodyne method.

Conclusions:

• The proposed short-delay self-homodyne method offers a simpler structure and enhanced precision for laser linewidth measurement.
• This technique is a promising substitute for complex self-heterodyne and traditional self-homodyne/heterodyne methods.
• The SPVD feature provides an effective means for precise laser linewidth determination.