Continuous-wave cavity ring-down polarimetry

Area of Science:

• Optical Physics
• Spectroscopy
• Materials Science

Background:

• Cavity-based spectropolarimetry is crucial for measuring optical properties.
• Traditional pulsed cavity ring-down polarimetry (CRDP) has limitations in spectral resolution and data acquisition rate.
• Existing cavity-enhanced polarimetric schemes often rely on intensity measurements.

Purpose of the Study:

• To introduce a novel cavity-based polarimetric scheme using continuous wave (CW) laser sources.
• To enhance sensitivity, time resolution, and spectral resolution in polarimetric measurements.
• To develop a robust and portable polarimetric instrumentation.

Main Methods:

• Employed rapidly pulsed single-frequency continuous wave (CW) laser sources.
• Developed a CW-CRDP modality based on measuring polarization rotation frequency during ring-down events.
• Utilized large intracavity polarization anisotropies to generate ring-down events.

Main Results:

• Demonstrated improved spectral resolution, signal intensity, and data acquisition rate compared to pulsed CRDP.
• Validated the technique for measuring the non-resonant Faraday effect in SiO2, CeF3, and gaseous butane.
• Showed that frequency-based methodology reduces the need for high finesse cavities.

Conclusions:

• The CW-CRDP technique offers significant advantages over traditional pulsed methods.
• The frequency-based approach enhances polarimetric sensitivity and broadens applicability.
• This methodology is particularly suitable for developing robust, portable polarimetric instruments.