High-contrast coherent population trapping based on crossed polarizers method

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Optics
• Metrology

Background:

• Coherent Population Trapping (CPT) is a quantum interference effect crucial for high-precision measurements.
• Existing methods for observing CPT resonance can be complex, limiting their application in miniaturized devices.
• Chip-scale atomic clocks (CSACs) require robust and simple optical systems for CPT resonance detection.

Purpose of the Study:

• To develop a simple and high-contrast method for observing CPT resonance.
• To adapt the method for potential use in chip-scale atomic clocks (CSACs).
• To theoretically model and experimentally validate the performance of the developed method.

Main Methods:

• A novel optical setup utilizing crossed polarizers to observe CPT resonance.
• Theoretical calculation of Faraday rotation in a linearly polarized light field (lin||lin) using Λ-system models.
• Experimental measurement of resonance contrast and linewidth using a Cesium (Cs) gas cell and a D1-line Vertical-Cavity Surface-Emitting Laser (VCSEL).

Main Results:

• The crossed-polarizer method provides a simple optical system suitable for CPT resonance observation.
• Theoretical predictions for Faraday rotation spectra showed good agreement with experimental data.
• High resonance contrast (88.4%) and a narrow linewidth (1.15 kHz) were experimentally achieved.

Conclusions:

• The developed crossed-polarizer method is effective for observing high-contrast CPT resonance.
• The simplicity of the optical system makes it highly suitable for integration into chip-scale atomic clocks (CSACs).
• The experimental validation confirms the potential of this technique for advancing miniaturized atomic clock technology.