Angle-multiplexed hologram storage in LiNbO(3):Tb, Fe

Area of Science:

• Holography
• Photorefractive materials
• Optical data storage

Background:

• Near-stoichiometric lithium niobate (LiNbO3) crystals doped with Tb and Fe exhibit UV-induced absorption.
• This photochromic behavior affects hologram multiplexing performance.

Purpose of the Study:

• To investigate hologram multiplexing in UV-preexposed LiNbO3:Tb, Fe crystals.
• To evaluate the feasibility of conventional recording schedules for photochromic materials.

Main Methods:

• Angle multiplexing of 50 plane-wave holograms using a 532 nm continuous-wave laser.
• Recording holograms in a UV-preexposed LiNbO3:Tb, Fe crystal.

Main Results:

• Recording sensitivity decreased gradually due to bleaching of UV-induced absorption.
• A conventional recording schedule for equal diffraction efficiency was found to be applicable.
• Increased erasure-time constants compensated for reduced sensitivity in later holograms.
• An M/# of 1.73 was achieved in a 3.3-mm thick crystal.

Conclusions:

• Hologram multiplexing is feasible in photochromic LiNbO3:Tb, Fe crystals.
• Conventional recording schedules can be employed despite sensitivity variations.
• The material's properties allow for effective multi-hologram storage.