Simple delay-limited sideband locking with heterodyne readout.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Physics and Technology
• Precision Measurement

Background:

• High-finesse optical cavities are crucial for precision measurements.
• Traditional laser locking techniques can be complex and require significant optical power.
• Heterodyne readout offers advantages for signal detection but often necessitates complex setups.

Purpose of the Study:

• To present a robust sideband laser locking technique for applications demanding low probe power and heterodyne readout.
• To achieve high-bandwidth laser stabilization in ambient conditions.
• To enable alignment-free heterodyne detection without additional optical components.

Main Methods:

• Locking a first-order phase-modulation sideband to a high-finesse Fabry-Perot cavity.
• Utilizing a high-bandwidth voltage-controlled oscillator for feedback control.
• Employing a closed-loop system with a measured transfer function analysis.

Main Results:

• Achieved a closed-loop bandwidth of 3.5 MHz, limited by signal delay.
• Validated the system's performance against a theoretical model.
• Proposed a modified design for a potential bandwidth exceeding 6 MHz with high feedback gain.

Conclusions:

• The presented sideband laser locking technique is effective for low-power, heterodyne readout applications.
• The technique simplifies experimental setups by eliminating the need for extra lasers or modulators.
• The proposed design modifications offer pathways for further improvements in bandwidth and stability.