Photo-isomerization enabled reversible wavelength switching in fiber random laser for color image encryption

Area of Science:

• Photonics and Optics
• Materials Science
• Information Security

Background:

• Random lasers offer unique spectral properties crucial for cryptography.
• Existing random lasers have limitations in key generation for secure image encryption.

Purpose of the Study:

• To develop a reversible, switchable wavelength fiber random laser.
• To utilize this laser for a dual chaotic color image encryption system.

Main Methods:

• Fabrication of a fiber random laser using a mixture of polarized intramolecular charge transfer dye molecules and titanium dioxide in a polyvinyl alcohol matrix.
• Utilizing excited state intramolecular proton transfer and photo-isomerization for wavelength switching.
• Coating the mixture on a fiber via dip coating, followed by a polydimethylsiloxane layer.

Main Results:

• Achieved a low threshold of 32 µJ/cm² with a narrow FWHM of 0.4 nm.
• Demonstrated dual emission reversible switchable wavelength bands centered at 443 nm and 464 nm.
• Integrated the laser into a dual chaotic color image encryption system with low beam divergence (<20°).

Conclusions:

• The developed fiber random laser provides a robust solution for secure image encryption.
• The switchable dual-wavelength emission enhances the complexity and security of chaotic encryption.
• This work highlights the potential of fiber random lasers in advanced information security applications.