Note: Compact optical fiber coupler for diamond anvil high pressure cells

Area of Science:

• Optics and Photonics
• Materials Science
• High-Pressure Physics

Background:

• Diamond anvil cells (DACs) are crucial for high-pressure research but often have limited optical access.
• Integrating optical measurements within DACs, especially under extreme conditions (low temperature, high magnetic fields), presents significant challenges.
• Existing methods for optical interrogation of samples in DACs can be cumbersome or incompatible with certain experimental setups.

Purpose of the Study:

• To develop a compact and versatile optical fiber coupler for precise light delivery and collection within a diamond anvil high-pressure cell.
• To enable optical measurements in challenging environments, including low temperatures and high magnetic fields, where traditional optical access is limited.
• To demonstrate the utility of the coupler for in-situ pressure determination.

Main Methods:

• Development of a compact optical fiber coupler with integrated focusing optics and adjustments.
• Integration of the coupler with a diamond anvil cell for light transmission to and from the sample.
• Utilizing the coupler to perform ruby fluorescence spectroscopy for pressure measurement at cryogenic temperatures (1.2 K).
• Fabrication of the coupler using nonmagnetic beryllium copper for compatibility with high magnetic fields.

Main Results:

• The developed coupler allows precise focusing of light onto the sample within the DAC, despite its compact size.
• Successful demonstration of in-situ pressure measurement at 1.2 K using ruby fluorescence, showcasing the coupler's capability in low-temperature environments.
• The nonmagnetic construction facilitates its use in high magnetic fields, opening possibilities for combined high-pressure, low-temperature, and high-magnetic-field studies.
• The coupler is suitable for a broad range of optical measurements under high pressure.

Conclusions:

• A novel, compact optical fiber coupler significantly enhances the capabilities of diamond anvil cells for optical measurements.
• The coupler overcomes limitations of optical access in extreme experimental conditions, including low temperatures and high magnetic fields.
• This development is valuable for various scientific disciplines requiring in-situ optical characterization under high pressure.