First demonstration of an all-solid-state optical cryocooler

Area of Science:

• Physics
• Materials Science
• Optical Engineering

Background:

• Solid-state optical refrigeration utilizes anti-Stokes fluorescence for vibration-free cooling of macroscopic objects to cryogenic temperatures.
• Previous research demonstrated laser cooling of Yb3+-doped YLiF4 (YLF:Yb) crystals to 91 K.

Purpose of the Study:

• To demonstrate laser cooling of a payload attached to a cooling crystal for the first time.
• To develop an all-solid-state optical cryocooler for practical applications, such as cooling sensors in spectrometers.

Main Methods:

• A YLF:Yb crystal was integrated into a Herriott cell and optically pumped with a 1020-nm laser (47 W).
• A HgCdTe sensor within a Fourier Transform Infrared (FTIR) spectrometer was cooled to 135 K.
• Heat flows were meticulously managed using a YLF thermal link and silica aerogel supports within a vacuum clamshell.

Main Results:

• Achieved laser cooling of a connected payload (HgCdTe sensor) to 135 K.
• Demonstrated the first all-solid-state optical cryocooler system.
• Minimized fluorescence heating and parasitic heat loads through optimized thermal management.

Conclusions:

• This study presents a viable method for laser cooling payloads, paving the way for advanced optical cryocoolers.
• The developed structure provides a baseline for future optical cryocooler designs, applicable to various sensitive electronic components.
• Effective thermal management is crucial for the success of solid-state optical refrigeration systems.