Photochromism induced by infrared two-photon absorption

Area of Science:

• Materials Science
• Optics
• Photochemistry

Background:

• Photochromic materials change color upon light exposure.
• Rare-earth doped materials can absorb and emit light at specific wavelengths.
• Combining these materials can lead to novel optical functionalities.

Purpose of the Study:

• To investigate the photochromic reaction in acrylate containing spirobenzopyran and rare-earth doped oxide (Gd2O2S:YbEr) induced by infrared (IR) laser.
• To explore the mechanism of IR-induced photochromism via rare-earth upconversion.
• To demonstrate the reversibility of the photochromic process.

Main Methods:

• An acrylate material doped with spirobenzopyran and Gd2O2S:YbEr was synthesized.
• The material was irradiated with a 940 nm IR laser.
• The color change and spectral properties were analyzed.
• Reversibility was tested using thermal relaxation and UV irradiation.

Main Results:

• A 940 nm IR laser induced a photochromic reaction in the acrylate.
• Rare-earth elements (YbEr) in Gd2O2S absorbed two 940 nm photons and emitted a 550 nm photon.
• The emitted 550 nm photon caused photochromic isomerization of spirobenzopyran.
• The material returned to its original orange color via thermal relaxation or UV irradiation and could be bleached again by IR laser.

Conclusions:

• IR laser light can induce photochromic reactions in acrylate doped with spirobenzopyran and rare-earth elements.
• Rare-earth upconversion is a viable mechanism for triggering photochromism with IR light.
• The developed material exhibits reversible photochromic behavior, suggesting potential applications in optical data storage and smart windows.