Optical phase-locking of two extended-cavity diode lasers by serrodyne modulation

Area of Science:

• Optics and Photonics
• Quantum Technology

Background:

• Precise frequency control of lasers is crucial for advanced applications like atom interferometry.
• Extended-cavity diode lasers offer tunable narrow linewidths but require stable phase-locking for high-precision measurements.

Purpose of the Study:

• To demonstrate optical phase-locking between two extended-cavity diode lasers with a significant frequency offset.
• To characterize the performance of the phase-locking loop in terms of bandwidth and residual phase noise.

Main Methods:

• Utilized serrodyne modulation to achieve optical phase-locking between two extended-cavity diode lasers.
• Extended the phase-locking loop bandwidth to 9.5 MHz for improved dynamic range.
• Measured residual phase noise across various offset frequencies.

Main Results:

• Successfully phase-locked two lasers with a 6.9 GHz frequency difference.
• Achieved a phase-locking loop bandwidth of 9.5 MHz.
• Demonstrated low residual phase noise: -130 dBrad²/Hz (1.5-9 kHz) and below -120 dBrad²/Hz (150 Hz-350 kHz).

Conclusions:

• Optical phase-locking of extended-cavity diode lasers is feasible with a 6.9 GHz frequency difference.
• The achieved phase-locking performance is suitable for enhancing the sensitivity of atom interferometers.
• This technique offers a pathway to improved precision in quantum sensing and metrology.