Power-area method to precisely estimate laser linewidth from its frequency-noise spectrum

Area of Science:

• Laser physics
• Optical metrology
• Spectroscopy

Background:

• Laser linewidth is a critical parameter affecting various applications.
• Existing methods for linewidth estimation can be complex or lack precision.
• Understanding frequency noise sources is essential for laser performance.

Purpose of the Study:

• To introduce a precise and simple method for laser linewidth estimation.
• To validate the method's accuracy for different noise types and interferometry.
• To optimize linewidth compression techniques using the proposed method.

Main Methods:

• Developed the power-area method (PAM) based on frequency power spectral density.
• Applied PAM to quantify white-frequency and flicker-frequency noise.
• Utilized PAM to analyze the beat note in delayed self-homodyne/heterodyne interferometry.
• Investigated servo-loop control parameters (gain, bandwidth) with PAM.

Main Results:

• Achieved less than 7% error in estimating the full width at half-maximum (FWHM) for frequency noise.
• Successfully estimated the FWHM of the beat note using PAM.
• Identified optimal servo-loop parameters for enhanced linewidth compression.

Conclusions:

• The power-area method (PAM) offers a precise and simple approach to laser linewidth estimation.
• PAM is effective for characterizing frequency noise and analyzing interferometric beat notes.
• The method aids in optimizing laser linewidth compression through servo-loop control.