Two-wave mixing amplification of femtosecond laser pulses at 800nm in Rh:BaTiO₃ photorefractive crystal

We report the photorefractive (PR) two-wave mixing amplification (TWMA) of broadband femtosecond laser pulses in a Rh:BaTiO₃ crystal by one-photon absorption. Two-wave mixing (TWM) is performed in the crystal using 30fs laser pulses at an 800 nm wavelength. A maximum two-wave mixing amplification gain coefficient of ∼11/cm was achieved using a chirped volume grating written at a grating spacing of 5 μm. The broadband spectrum and the original phase characteristics of the signal pulse are also maintained. Beam fanning for the femtosecond pulse laser is less pronounced than that for the cw laser, facilitating a higher two-wave mixing gain for femtosecond pulse lasers.