Optimal alignment sensing of a readout mode cleaner cavity.

Area of Science:

• Optics
• Laser Physics
• Signal Processing

Background:

• Resonant optical cavities are crucial for mode cleaning in laser systems to enhance signal-to-noise ratio (SNR).
• Optimal SNR depends critically on precise alignment of the mode cleaner to the laser beam's signal encoding.
• Traditional automatic alignment systems, sensitive to carrier fields, do not guarantee optimal SNR.

Purpose of the Study:

• To develop an improved automatic alignment system for optical mode cleaners.
• To enhance the signal-to-noise ratio (SNR) by optimizing alignment sensitivity to signal sidebands.
• To demonstrate a practical method for improving alignment in kilometer-scale detectors.

Main Methods:

• Modified traditional dither alignment sensing.
• Applied large amplitude modulation to the signal field.
• Generated error signals sensitive to signal sideband field alignment.

Main Results:

• Achieved error signals sensitive to signal sideband field alignment.
• Demonstrated a factor of 3 improvement in detected SNR.
• Validated the approach in a kilometer-scale detector for gravitational wave observation.

Conclusions:

• The modified dither alignment approach effectively improves SNR in optical systems.
• This method offers enhanced sensitivity to signal sidebands for better alignment.
• The technique is generalizable to various alignment sensors and optical detection systems.