Linewidth Measurement of a Narrow-Linewidth Laser: Principles, Methods, and Systems.

Area of Science:

• Optics and Photonics
• Laser Physics
• Metrology

Background:

• Narrow-linewidth lasers are essential for satellite communications, precision measurements, and high-speed optical networks.
• Technological advancement in these fields relies heavily on precise laser linewidth measurement techniques.
• Existing methods often involve complex setups with long optical fibers and significant phase noise jitter.

Purpose of the Study:

• To provide a theoretical analysis of linewidth characterization methods.
• To review existing measurement technologies and their limitations.
• To introduce and elaborate on a novel short-delay self-heterodyne method for improved phase noise reduction.

Main Methods:

• Theoretical analysis of beat frequency power spectrum and laser phase noise calculations.
• Review and assessment of existing laser linewidth measurement technologies.
• In-depth discussion of a short-delay self-heterodyne method using coherent envelope spectrum demodulation.

Main Results:

• Analysis of performance parameters and testing conditions for various lasers and characterization methods.
• Identification of measurement accuracy and error sources in different techniques.
• Demonstration of the short-delay self-heterodyne method's potential to reduce phase jitter from 1/f noise.

Conclusions:

• Precise laser linewidth measurement is critical for advancing key technologies.
• The short-delay self-heterodyne method offers a promising solution to overcome limitations of existing techniques.
• Further research and application of this method can enhance laser performance and reliability.