Polarization multiplexed write-once-read-many optical data storage in bacteriorhodopsin films

Area of Science:

• Biophysics
• Materials Science
• Optical Engineering

Background:

• Bacteriorhodopsin (BR) is a light-activated protein with potential applications in optical data storage.
• Previous studies observed a photoconversion product (F620 state) in BR films using nanosecond laser pulses, exhibiting nonlinear absorption.

Purpose of the Study:

• To investigate the generation and properties of the F620 photoproduct in BR films using femtosecond laser pulses.
• To evaluate the potential of BR films for high-density optical data storage, specifically Write-Once-Read-Many (WORM) applications.

Main Methods:

• Excitation of bacteriorhodopsin films with 532 nm femtosecond laser pulses.
• Characterization of the resulting photoproduct's absorption properties (nonlinear and anisotropic).
• Assessment of the photoproduct's thermal stability and photochemical reversibility.

Main Results:

• Femtosecond laser pulses generate a photoproduct similar or identical to the F620 state observed with nanosecond pulses.
• The photoproduct exhibits strong nonlinear and anisotropic absorption, suitable for polarization data storage.
• The photoproduct is thermally stable and not photoreversible to the initial B state, indicating a two-photon absorption process.

Conclusions:

• Bacteriorhodopsin films are suitable for optical WORM data storage, leveraging polarization multiplexing.
• Femtosecond laser excitation enables extremely fast recording times, facilitating very high data volumes.
• The combination of polarization states and rapid recording offers a promising pathway for advanced optical data storage solutions.