Laser optical feedback imaging controlled by an electronic feedback loop.

Area of Science:

• Optics
• Laser Physics
• Interferometry

Background:

• Autodyne interferometry involves internal beating of reference and signal beams within the laser cavity.
• Laser relaxation oscillations significantly impact signal-to-noise ratio (SNR) and response time in these systems.
• Laser Optical Feedback Imaging (LOFI) is a technique utilizing these principles.

Purpose of the Study:

• To experimentally investigate the SNR and response time of a LOFI interferometer.
• To compare image quality under free laser dynamics versus controlled dynamics using electronic feedback.
• To assess the potential for high-speed LOFI with improved sensitivity.

Main Methods:

• Utilized a Nd(3+) microchip laser with a megahertz relaxation frequency.
• Experimentally analyzed SNR and response time.
• Compared image quality with and without a stabilizing electronic feedback loop (differentiator).

Main Results:

• Shorter laser response times (lower LOFI gain) correlate with improved image quality (higher LOFI SNR).
• An adapted electronic feedback loop enables high-speed LOFI.
• Achieved shot-noise limited sensitivity in high-speed LOFI.

Conclusions:

• Optimizing laser dynamics through electronic feedback enhances LOFI performance.
• High-speed LOFI with excellent sensitivity is achievable.
• Experimental results align with theoretical predictions, validating the approach.