Optical memory in DuPont photopolymers by using femtosecond laser pulses

To investigate the feasibility of a high density optical memory in photopolymers, we used two-photon absorption of near-infrared femtosecond laser pulses to perform bit-wise three-dimensional storage. We monitored the transmitted probe beam, which was modulated by the change of refractive index caused by the femtosecond laser irradiation. The size of the spots generated by the focused Gaussian beam depended on the laser intensity and exposure time. The minimum lateral and longitudinal sizes of a spot were estimated as 0.5 and 5 mu m, respectively.