Evaluation method for the optical feedback factor and linewidth enhancement factor using phase discontinuities in...

Area of Science:

• Optics and Photonics
• Laser Physics
• Metrology

Background:

• Self-mixing interferometry (SMI) is crucial for remote target measurement (displacement, distance, velocity).
• Accurate evaluation of optical feedback factor (C) and linewidth enhancement factor (α) is essential for laser diode parameter calculation and SMI signal processing.
• Existing methods face challenges in arbitrary waveform analysis.

Purpose of the Study:

• To propose a novel evaluation method for optical feedback factor (C) and linewidth enhancement factor (α) in arbitrary waveforms.
• To enhance the accuracy of SMI signal processing and laser diode parameter estimation.
• To provide a robust method applicable to low-cost semiconductor lasers.

Main Methods:

• Investigating the slopes of phase discontinuity distribution in the optical feedback regime (1
• Developing an algorithm utilizing slope variation of phase discontinuity distribution.
• Implementing a discontinuity selection method based on cumulative distribution effects for improved accuracy.

Main Results:

• Clarified the influence of phase discontinuity slope distribution on predicting C and α.
• Successfully evaluated C and α using the proposed algorithm and discontinuity selection method.
• Verified the method's efficacy through both simulations and experimental validation with a semiconductor laser.

Conclusions:

• The proposed method accurately evaluates optical feedback and linewidth enhancement factors for arbitrary waveforms.
• This technique improves measurement accuracy in self-mixing interferometry.
• The findings are validated for practical applications using low-cost semiconductor lasers.