Three-dimensional recording by tightly focused femtosecond pulses in LiNbO3

The authors report on a three-dimensional single-shot optical recording by 150 fs pulses at 800 nm wavelength in Fe doped LiNbO3. The rewritable bits (2x×2y×8z μm3) are demonstrated. The highest refractive index modulation of ∼ 10−3 per single pulse has been formed by preferential photovoltaic effect at close to the dielectric breakdown irradiance of ∼ TW/cm2 and was independent of polarization (in respect to the c axis). The achievable refractive index modulation is evaluated and the recording mechanisms are discussed.