Advances in Laser Linewidth Measurement Techniques: A Comprehensive Review

Area of Science:

• Optics and Photonics
• Laser Physics
• Metrology

Background:

• Laser linewidth is a critical parameter defining spectral characteristics.
• Accurate linewidth measurement is essential for diverse advanced laser applications.
• Existing techniques cover a wide range from GHz to sub-Hz regimes.

Purpose of the Study:

• To systematically review recent advances in laser linewidth measurement techniques.
• To provide a comprehensive technical reference for laser development and characterization.
• To compare methods for both broad and narrow linewidth lasers.

Main Methods:

• Review of direct spectral measurement and Fabry-Pérot interferometry for broad linewidths.
• Detailed analysis of the optical beating method for narrow linewidths.
• Comparison of power spectral density (PSD) analysis and phase-noise evaluation for beat signals.

Main Results:

• Established techniques for broad linewidths include spectrometers and interferometers.
• Optical beating, PSD analysis, and phase-noise evaluation are key for narrow linewidths.
• Recent innovations in ultra-high-precision linewidth metrology are examined.

Conclusions:

• The review provides a comparative assessment of techniques, including principles, configurations, resolution, and limitations.
• It serves as a valuable resource for understanding and applying various laser linewidth measurement methods.
• The content supports the development, characterization, and application of lasers across different spectral ranges.