Single step zero-thermal-expansion temperature measurement of optical reference cavities

Area of Science:

• Physics
• Optical Engineering
• Metrology

Background:

• Achieving ultra-high laser frequency stability (10^-17) relies on reference cavities within thermal enclosures.
• Minimizing thermal fluctuations requires precise control at the material's zero-thermal-expansion temperature (ZTE temp).
• Traditional methods for ZTE temp determination are time-consuming, especially for systems with large thermal time constants.

Purpose of the Study:

• To develop a rapid and precise method for measuring the zero-thermal-expansion temperature of laser reference cavities.
• To enable faster optimization of thermal control systems for enhanced laser frequency stability.
• To validate a novel measurement technique through theoretical modeling and experimental verification.

Main Methods:

• Development of a theoretical model predicting laser performance when locked to a reference cavity.
• Construction of an experimental evaluation system to verify the theoretical model.
• Implementation of a single temperature scan method for rapid ZTE temperature measurement.

Main Results:

• A theoretical model for laser-cavity interaction and performance was successfully developed.
• An evaluation system confirmed the model's predictions.
• The zero-thermal-expansion temperature of a 30-cm cavity was accurately measured as 4.3 ± 0.5 °C using the novel method.

Conclusions:

• The developed fast measurement method significantly reduces the time required to determine the zero-thermal-expansion temperature.
• This technique offers high precision, crucial for optimizing cavity-stabilized lasers.
• The method is valuable for improving the long-term frequency stability of state-of-the-art lasers.