Scientists at Japan Science and Technology Corp. in Kawasaki and at Tokyo Institute of Technology in Yokohama, Japan, have demonstrated a holographic technique that writes structures inside glass using a single laser. The work may find use in 3-D memory storage and in the fabrication of gratings for optical applications.Reported in the Aug. 5 Applied Physics Letters, the technique employs 0.5- to 5-ps chirped pulses of 800-nm radiation from a Ti:sapphire laser. The researchers split the output of the laser and crossed the pulses inside the silica targets. The peak power at the focal point is sufficiently high to generate free carriers, enabling the residual pulse envelopes to be absorbed or reflected and thereby to inscribe patterns within the target. The technique is suitable for use with all transparent dielectric materials.