Two-Photon Absorption Recording in Photochromic Diarylethenes Using Laser Diode for Three-Dimensional Optical Memory

Abstract

We have studied two-photon absorption (TPA) recording in photochromic diarylethenes for a three-dimensional (3D) optical memory, and demonstrated the TPA recording for the first time using a laser diode with a pulse width of 2 ns without a thermal influence. In comparison with the recording sensitivity by a femtosecond fiber laser, it was found that the peak power can be greatly reduced and the TPA sensitivity has squared characteristics depending on the pulse width range from 94 fs to 2 ns. Finite difference time domain (FDTD) analysis of optical intensity through refractive pits suggests that 3D recording in multilayered medium is more suitable, because optical aberrations induced by the lens effect of refractive pits are greatly reduced and the reflectance from a pit is improved, in comparison with that in a bulk medium.