抄録
We have proposed a ″holographic encoding technique by an interfered infrared femtosecond laser pulse″. In this technique, holographic gratings are encoded on the surface of various nonphotosensitive materials such as dopant-free silica glass and diamond as a consequence of the interference of two femtosecond pulses split from a single pulse. Varying the angle between the two crossed pulses changed the encoded periodic spacing. A minimum periodic spacing of ~ 430 nm was achieved for a laser wavelength of 800 nm. Furthermore, we have succeeded in encoding refractive index-modulated volume-type gratings deep inside pure silica glass and sapphire crystals if we use a single chirped (0.2 ∼5 ps duration) laser pulse. The present technique provides a fast method applicable for encoding volume-type gratings inside any nonphotosensitive transparent dielectric materials and for fabricating optical devices such as distributed-feed-back lasers and multilayered memories.
